package Torello.Java;

import java.io.*;
import java.util.*;
import java.util.zip.*;
import java.util.stream.*;
import java.nio.file.*;
import java.lang.reflect.InvocationTargetException;

import Torello.Java.Additional.*;

import Torello.JavaDoc.Annotations.StaticFunctional;
import Torello.JavaDoc.Annotations.StaticFunctional.Excuse;

/**
 * Operating-System independent File Read & Write utilities that reduce many common Java
 * File I/O Commands to a single method invocation, focusing heavily on Java's Serialization
 * feature.
 * 
 * <EMBED CLASS='external-html' DATA-FILE-ID=FILE_RW>
 */
@StaticFunctional(Excused="TRUNCATE_EOF_CHARS", Excuses=Excuse.FLAG)
public class FileRW
{
    private FileRW() { }

    /**
     * This is used by method {@link #loadFileToString(String)}.  By default this flag is set to
     * {@code TRUE}, and when it is, any trailing {@code EOF chars, ASCII-0} found in a file that
     * is to be interpreted as a Text-File, will be truncated from the {@code String} returned by
     * that {@code 'reader'} method.
     */
    public static boolean TRUNCATE_EOF_CHARS = true;


    // ********************************************************************************************
    // ********************************************************************************************
    // writeFile
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * Writes the entire contents of a single {@code java.lang.String} to a file on the File-System
     * named {@code 'fName'}.
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_WRITABLE_DIR>
     * 
     * @param s A {@code java.lang.String} which is appended, in entirety, to the file ('fName')
     *
     * @param fName The name of the file to which the contents of the {@code java.lang.String}
     * are appended.  If This file doesn't already exist, it is created here.
     *
     * @throws IOException If any I/O errors have occurred with the File-System / disk.
     */
    public static void writeFile(CharSequence s, String fName) throws IOException
    {
        File outF = new File(fName);

        outF.createNewFile();

        // This writer is 'java.lang.AutoCloseable'.
        //
        // NOTE: The IOException will still be thrown out of this method if it occurs.  It is not
        //       caught!

        try
            (FileWriter fw = new FileWriter(outF))
            { fw.write(s.toString()); }
    }

    /**
     * This takes an {@code Iterable<String>}, and a filename, and writes each
     * {@code java.lang.String} in the {@code Iterator} that it produces to the file 
     * specified by File-Name parameter {@code 'fName'}
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_WRITABLE_DIR>
     * 
     * <BR /><DIV CLASS=JDHintAlt>
     * <B STYLE='color:red;'>New-Line Characters:</B> A newline {@code ('\n')} is appended to the
     * end of each {@code java.lang.String} before writing it to the file.
     * </DIV>
     *
     * @param i This is any java {@code Iterable<String>} object.  Each of these will be written,
     * in succession, to the file named by parameter {@code 'fName'}
     *
     * @param fName The name of the file to which the contents of the {@code java.lang.String}
     * are appended.  If This file doesn't already exist, it is created here.
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or
     * disk operation.
     */
    public static void writeFile(Iterable<String> i, String fName) throws IOException
    {
        Iterator<String> iter = i.iterator();

        File outF = new File(fName);

        outF.createNewFile();

        // This writer is 'java.lang.AutoCloseable'.
        //
        // NOTE: The IOException will still be thrown out of this method if it occurs.  It is not
        //       caught!

        try
            (FileWriter fw = new FileWriter(outF))
            { while (iter.hasNext()) fw.write(iter.next() + "\n"); }
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // writeFile_NO_NEWLINE
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * This takes an {@code Iterable} of String, and a filename and writes each
     * {@code java.lang.String} in the {@code Iterator} that it produces to the file specified by
     * File-Name parameter {@code 'fName'}
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_WRITABLE_DIR>
     * 
     * <BR /><DIV CLASS=JDHintAlt>
     * <B STYLE='color:red;'>New-Line Characters:</B> In this function a newline {@code ('\n')}
     * character <I>is <B>not</B> appended</I> to the end of each {@code java.lang.String} of the
     * input {@code Iterator}.
     * </DIV>
     *
     * @param i This is any java {@code 'Iterable'} object that can iterate {@code 'String'}.
     * Each of these will be written, in succession, to the file named by {@code 'fName'}
     *
     * @param fName The name of the file to which the contents of the {@code java.lang.String}
     * are appended.  If This file doesn't already exist, it is created here.
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or disk
     * operation.
     */
    public static void writeFile_NO_NEWLINE(Iterable<String> i, String fName) throws IOException
    {
        Iterator<String> iter = i.iterator();

        File outF = new File(fName);

        outF.createNewFile();

        // This Writer is 'java.lang.AutoCloseable'.
        //
        // NOTE: The IOException will still be thrown out of this method if it occurs.  It is not
        //       caught!

        try
            (FileWriter fw = new FileWriter(outF))
            { while (iter.hasNext()) fw.write(iter.next()); }
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // appendToFile
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * Appends the entire input {@code java.lang.String} - actually a
     * {@code java.lang.CharSequence} to the file on the File-System named {@code 'fName'}
     * 
     * <BR /><BR /><DIV CLASS=JDHint>
     * <B STYLE='color:red;'>Directory Requirements:</B> Though the file does not need to exist
     * already in order for this file to be written the directory hierarchy needs to exist, or a
     * Java {@code 'IOException'} will occur.
     * </DIV>
     *
     * @param s A {@code java.lang.CharSequence} (almost identical to {@code 'String'}) which is
     * appended, in entirety, to the File-Name parameter {@code 'fName'}
     *
     * @param fName The name of the file to which the contents of the {@code java.lang.String} are
     * appended.  If This file doesn't already exist, it is created here.
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or
     * disk operation.
     */
    public static void appendToFile(CharSequence s, String fName) throws IOException
    {
        File f = new File(fName);

        if (! f.exists()) f.createNewFile();

        Files.write(Paths.get(fName), s.toString().getBytes(), StandardOpenOption.APPEND);
    }

    /**
     * This takes an {@code Iterable<String>}, and a filename, and appends each
     * {@code java.lang.String} in the {@code Iterator} that it produces to the file 
     * specified by File-Name parameter {@code 'fName'}
     *
     * <BR /><BR /><DIV CLASS=JDHint>
     * <B STYLE='color:red;'>Directory Requirements:</B> Though the file does not need to exist
     * already in order for this file to be written the directory hierarchy needs to exist, or a
     * Java {@code 'IOException'} will occur.
     * </DIV>
     *
     * @param i This is any java {@code Iterable<String>} object.  Each of these will be written,
     * in succession, to the file named by parameter {@code 'fName'}
     *
     * @param fName The name of the file to which the contents of the {@code java.lang.String}
     * are appended.  If This file doesn't already exist, it is created here.
     *
     * @param addNewLines When this parameter is passed {@code TRUE}, a New-Line character will be
     * appended after each {@code String} that is written.  When {@code FALSE}, only the
     * {@code String's} produced by the {@code Iterable}, themselves, are appended to the file.
     * 
     * @throws IOException If an I/O error has occurred as a result of the File-System or
     * disk operation.
     */
    public static void appendToFile(Iterable<String> i, String fName, boolean addNewLines)
        throws IOException
    {
        File f = new File(fName);

        if (! f.exists()) f.createNewFile();


        // Uses the "Ternary Operator" / "Conditional Operator" Syntax, but it's a little hard to
        // read that.  There is a '?' and a ':' after the boolean 'addNewsLines'

        Iterable<String> passedIterable = addNewLines


            // If the user has requested to add newlines, wrap the passed Iterable inside of a new
            // Iterable that appends a new-line character to the output of the User's 'next()'
            // method (which is just returning the String's to be written to disk - less the newline)

            ?   new Iterable<>()
                {
                    private final Iterator<String> iterInternal = i.iterator();


                    // Funny Note: All an "Iterable" is is an Object that returns an Iterator.  The
                    // interface "Iterable" only has one non-Default Method - iterator().  Re-Write
                    // that method to return a slightly altered Iterator<String>

                    public Iterator<String> iterator()
                    {
                        return new Iterator<String>()
                        {
                            public boolean  hasNext()   { return iterInternal.hasNext();        }
                            public String   next()      { return iterInternal.next() + '\n';    }
                        };
                    }
                }

            // Otherwise, just assign the Users Iterable to the "passedIterable" Variable
            : i;

        // Now write the Passed Iterable of String, using java.nio.file.Files
        Files.write(Paths.get(fName), passedIterable, StandardOpenOption.APPEND);
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // Load File (as String's}
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * This will load the entire contents of a Text-File on disk to a single
     * {@code java.lang.String}
     * 
     * <BR /><BR /><DIV CLASS=JDHint>
     * <B STYLE='color:red;'>Trailing Zeros:</B> Some of the ugliest code to see is that which
     * scans for {@code 'EOF'} characters that have been liberally inserted into a simple
     * Text-File.  When reading a file (which, regardless of whether it <B>actually is a
     * Text-File</B>), this method will remove any <B>trailing {@code ASCII-0}</B> characters
     * (literally, {@code char c == 0}) from the files that are read.
     * </DIV>
     * 
     * <BR />Finding {@code '.html'} or {@code '.java'} files in which some editor (for whatever
     * reason) has inserted {@code EOF-like} characters to the end of the text can make programming
     * a headache.
     * 
     * <BR /><BR />Suffice it to say, the {@code String} that is returned from this method will
     * contain the last non-zero character (including CRLF, {@code '\n'} or {@code '\r'}
     * character that was read from the file.  Operating-systems do not require that a file have a
     * trailing zero to interpret them.
     * 
     * <BR /><BR />Character {@code '0'} is a legacy / older-version of the EOF Marker.
     * {@code '.java'}-Files certainly don't need them, and they can actually be a problem when a
     * developer is checking for file's that have equal-{@code String's} in them.
     *
     * <BR /><BR /><DIV CLASS=JDHintAlt>
     * <B STYLE='color:red;'>Static Boolean-Flag:</B> This class (class {@code FileRW}) has a
     * {@code static, boolean} flag that is able to prevent / shunt this 'Trailing Zero Removing'
     * behavior.  When {@link #TRUNCATE_EOF_CHARS} is set to {@code FALSE}, reading a file into a
     * {@code String} using this method will return the {@code String} - <B>including as many 
     * Trailing Zero-Characters as have been appended to the end of that file</B>.
     * </DIV>
     * 
     * @param fName the File-Name of a valid Text-File in the File-System
     *
     * @return The entire contents of the file as a {@code String}.
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or
     * disk operation.
     */
    public static String loadFileToString(String fName) throws IOException
    {
        // The reader is  'java.lang.AutoCloseable'.
        //
        // NOTE: The IOException will still be thrown out of this method if it occurs.  It is not
        //       caught!

        try
            (FileReader fr = new FileReader(fName))
        {
            int     len             = (int) new File(fName).length();
            char[]  cArr            = new char[len];
            int     offset          = 0;
            int     charsRead       = 0;
            int     charsRemaining  = len;

            while ((offset < len) && ((charsRead = fr.read(cArr, offset, charsRemaining)) != -1))
            {
                offset          += charsRead;
                charsRemaining  -= charsRead;
            }

            len = cArr.length;

            if (TRUNCATE_EOF_CHARS) while ((len > 0) && (cArr[len-1] == 0)) len--;

            return (len != cArr.length) ? new String(cArr, 0, len) : new String(cArr); 
        }
    }

    /**
     * Convenience Method.
     * <BR />Invokes: {@link #loadFileToStream(String, boolean)}
     * <BR />Converts: {@code Stream<String>} into {@code String[]}
     */
    public static String[] loadFileToStringArray(String fName, boolean includeNewLine)
        throws IOException
    { return loadFileToStream(fName, includeNewLine).toArray(String[]::new); }

    /**
     * This will load a file to a Java {@code Stream} instance.
     *
     * @param fName A File-Name of a valid Text-File in the File-System.
     * 
     * @param includeNewLine if this is {@code TRUE}, a {@code '\n'} (newline/CRLF) is appended to
     * the end of each {@code java.lang.String} read from this file.  If not, the original newline
     * characters which occur in the file, will be eliminated.
     * 
     * <BR /><BR /><DIV CLASS=JDHint>
     * This method will make one (potentially minor) mistake.  If the final character in the
     * input-file is, itself, a new-line (if the file ends with a {@code 'CRLF' / 'CR'}), then this
     * method should return a {@code Stream<String>} that is identical to the original file.
     * However, <B>if the final character in the file <SPAN STYLE='color:red;'>is not</SPAN> a
     * new-line {@code '\n'}</B>, then the {@code Stream<String>} that is returned will have an
     * extra new-line appended to the last {@code String} in the {@code Stream}, and the resultant
     * {@code Stream<String>} will be longer than the original file by 1 character.
     * </DIV>
     *
     * @return The entire contents of the file as a series of {@code java.lang.String} contained by
     * a {@code java.util.stream.Stream<String>}.  Converting Java {@code Stream's} to other data
     * container types is as follows:
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=STRMCNVT>
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or disk
     * operation.
     */
    public static Stream<String> loadFileToStream(String fName, boolean includeNewLine)
        throws IOException
    {
        // These readers's are 'java.lang.AutoCloseable'.
        //
        // NOTE: The IOException will still be thrown out of this method if it occurs.  It is not
        //       caught!
        //
        // ALSO: In try-with-resources blocks, if there is a problem/exception, these
        //       classes are all (automatically) closed/flushed, in reverse order.

        try (
            FileReader      fr  = new FileReader(fName);
            BufferedReader  br  = new BufferedReader(fr);
        )
        {
            Stream.Builder<String>  b = Stream.builder();
            String                  s = "";

            if (includeNewLine)
                while ((s = br.readLine()) != null) b.add(s + "\n");

            else
                while ((s = br.readLine()) != null) b.add(s);

            return b.build();
        }
    }

    /**
     * Convenience Method.
     * <BR />Invokes: {@link #loadFileToCollection(Collection, String, boolean)}
     * <BR />Passes: Newly instantiated {@code Vector<String>} to {@code 'collectionChoice'}
     */
    public static Vector<String> loadFileToVector(String fName, boolean includeNewLine)
        throws IOException
    { return loadFileToCollection(new Vector<String>(), fName, includeNewLine); }

    /**
     * This method loads the contents of a file to a {@code java.util.Collection<String>} object, 
     * where each {@code java.lang.String} in the output / returned {@code Collection} is a
     * different "line of text" from the input-file.  This is identical to invoking:
     * 
     * <DIV CLASS=LOC>{@code
     * Collection<String> myTextFile = FileRW.loadFileToString("someFile.txt").split('\n')
     * }</DIV>
     *
     * <BR /><DIV CLASS=JDHint>
     * <B STYLE='color:red;'>Variable-Type Parameter:</B> This method uses Java's Variable-Type
     * Parameter syntax to allow the programmer to decide what type of {@code Collection<String>}
     * they would like returned from this method.  Common examples would include
     * {@code Vector<String>, ArrayList<String>, HashSet<String>}, etc...
     * </DIV>
     * 
     * <BR /><B CLASS=JDDescLabel>Loading EOF:</B>
     * 
     * <BR />This method will make one small mistake.  If the final character inside the input-file
     * is, itself, a new-line, then this method will return a Java {@code String-Collection} which
     * is is identical to the original file.
     * 
     * <BR /><BR />However, <I>if the final character in the file <B>is not</B> a new-line
     * {@code '\n'} character</I>, then the returned {@code Collection} will have an extra new-line
     * appended immediately after the last {@code String} in the {@code Collection}.  Furthermore,
     * the resultant {@code Collection<String>} will be longer than the original file by 1 character.
     *
     * @param collectionChoice This must be an instance of a class that extends Java's
     * base {@code class Collection<String>} - <I>using {@code 'String'} as the generic-type
     * parameter.</I>  It will be populated with the lines from a Text-File using the
     * {@code Collection.add(String)} method.
     * 
     * @param <T> This may be any class which extends {@code java.util.Collection}.  It is
     * specified as a "Type Parameter" because this collection is returned as a result of this
     * function.  Perhaps it is superfluous to return the same reference that is provided by the
     * user as input to this method, but this certainly doesn't change the method signature or
     * make it more complicated.
     *
     * @param fName the File-Name of a valid Text-File on the File-System.
     *
     * @param includeNewLine if this is {@code TRUE}, a {@code '\n'} (newline/CRLF) is appended to
     * the end of each {@code java.lang.String} read from this file.  If not, the original newline
     * characters which occur in the file, will be eliminated.
     *
     * @return An identical reference to the reference passed to parameter
     * {@code 'collectionChoice'}
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or disk
     * operation.
     */
    public static <T extends Collection<String>> T loadFileToCollection
        (T collectionChoice, String fName, boolean includeNewLine)
        throws IOException
    {
        // These readers's are 'java.lang.AutoCloseable'.
        //
        // NOTE: The IOException will still be thrown out of this method if it occurs.  It is not
        //       caught!
        //
        // ALSO: In try-with-resources blocks, if there is a problem/exception, these
        //       classes are all (automatically) closed/flushed, in reverse order.

        try (
            FileReader      fr  = new FileReader(fName);
            BufferedReader  br  = new BufferedReader(fr);
        )
        {
            String s = "";

            if (includeNewLine)
                while ((s = br.readLine()) != null) collectionChoice.add(s + "\n");

            else
                while ((s = br.readLine()) != null) collectionChoice.add(s);
        }

        return collectionChoice;
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // Write ONE Object To File
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * Convenience Method.
     * <BR />Invokes: {@link #writeObjectToFile(Object, String, boolean)}
     * <BR />Catches Exception
     */
    public static boolean writeObjectToFileNOCNFE(Object o, String fName, boolean ZIP)
        throws IOException
    {
        try 
            { writeObjectToFile(o, fName, ZIP); return true; }

        catch (ClassNotFoundException cnfe) { return false; }
    }

    /**
     * Writes a {@code java.lang.Object} to a file for storage, and future reference.
     * 
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_WRITABLE_DIR>
     * 
     * @param o An {@code Object} to be written to a file as a <I><B>"Serializable"</B></I>
     * {@code java.lang.Object}
     *
     * @param fName The name of the output file
     *
     * @param ZIP a boolean that, when {@code TRUE}, will cause the object's data to be compressed
     * before being written to the output file.
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or disk
     * operation.
     *
     * @throws ClassNotFoundException This exception is thrown when the Java Virtual
     * Machine (JVM) tries to load a particular class and the specified class cannot be found in
     * the classpath.
     */
    public static void writeObjectToFile(Object o, String fName, boolean ZIP) 
        throws IOException, ClassNotFoundException
    {
        // These stream's are 'java.lang.AutoCloseable'.
        //
        // NOTE: The IOException and ClassNotFoundException will still be thrown out of this
        //       method if they occur.  They are not caught!
        //
        // ALSO: In try-with-resources blocks, if there is a problem/exception, these
        //       classes are all (automatically) closed/flushed, in reverse order.

        if (ZIP)

            try (
                FileOutputStream    fos     = new FileOutputStream(fName);
                GZIPOutputStream    gzip    = new GZIPOutputStream(fos);
                ObjectOutputStream  oos     = new ObjectOutputStream(gzip);
            )
                { oos.writeObject(o); }

        else

            try (
                FileOutputStream    fos     = new FileOutputStream(fName);
                ObjectOutputStream  oos     = new ObjectOutputStream(fos);
            )
                { oos.writeObject(o); }
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // Write ALL Objects ToFile
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * Convenience Method.
     * <BR />Invokes: {@link #writeAllObjectsToFile(Iterable, String, boolean)}
     * <BR />Catches Exception
     */
    public static boolean writeAllObjectsToFileNOCNFE(Iterable<?> i, String fName, boolean ZIP)
        throws IOException
    {
        try
            { writeAllObjectsToFile(i, fName, ZIP); return true; }

        catch (ClassNotFoundException cnfe) { return false; }
    }

    /**
     * Writes a series of {@code java.lang.Object} to a file for storage, and future reference.
     * 
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_1OBJ_FILE>
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_WRITABLE_DIR>
     * 
     * @param i A series, {@code Collection}, or {@code List} of {@code Object's} to be written
     * to a file in <I><B>Serializable</B></I> format.
     *
     * @param fName The name of the output file
     *
     * @param ZIP a {@code boolean} that, when {@code TRUE}, will cause the {@code Object's} 
     * data to be compressed before being written to the output-file.
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or
     * disk operation.
     *
     * @throws ClassNotFoundException This exception is thrown when the Java Virtual
     * Machine (JVM) tries to load a particular class and the specified class cannot be found in
     * the {@code CLASSPATH}.
     */
    public static void writeAllObjectsToFile(Iterable<?> i, String fName, boolean ZIP)
        throws IOException, ClassNotFoundException
    {
        Iterator<?> iter = i.iterator();

        // These stream's are 'java.lang.AutoCloseable'.
        //
        // NOTE: The IOException and ClassNotFoundException will still be thrown out of this
        //       method if they occur.  They are not caught!
        //
        // ALSO: In try-with-resources blocks, if there is a problem/exception, these
        //       classes are all (automatically) closed/flushed, in reverse order.

        if (ZIP)

            try (
                FileOutputStream    fos     = new FileOutputStream(fName);
                GZIPOutputStream    gzip    = new GZIPOutputStream(fos);
                ObjectOutputStream  oos     = new ObjectOutputStream(gzip);
            )
                { while (iter.hasNext()) oos.writeObject(iter.next()); }

        else

            try (
                FileOutputStream    fos     = new FileOutputStream(fName);
                ObjectOutputStream  oos     = new ObjectOutputStream(fos);
            )
                { while (iter.hasNext()) oos.writeObject(iter.next()); }
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // read ONE Object From File
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * Convenience Method.
     * <BR />Invokes: {@link #readObjectFromFile(String, boolean)}
     * <BR />Catches Exception
     */
    public static Object readObjectFromFileNOCNFE(String fName, boolean ZIP) throws IOException
    {
        try 
            { return readObjectFromFile(fName, ZIP); }

        catch (ClassNotFoundException cnfe) { return null; }
    }

    /**
     * Reads an {@code Object} from a Data-File which must contain a serialized
     * {@code java.lang.Object}.
     *
     * <DIV CLASS="EXAMPLE">{@code
     * // Create some Object for writing to the File-System, using Object Serialization
     * int[] dataArr = some_data_method();
     *
     * // It is always easier to pass 'true' to the compression boolean parameter
     * FileRW.writeObjectToFile(dataArr, "data/myDataFile.dat", true);
     *
     * ...
     *
     * // Later on, this file may be read back into the program, using this call:
     * Object o = FileRW.readObjectFromFile("data/myDataFile.dat", true);
     *
     * // This check prevents compiler-time warnings.  The Annotation "SuppressWarnings" 
     * // would also work.
     * dataArr = (o instanceof int[]) ? (int[]) o : null;
     * }</DIV>
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_1OBJ_FILE>
     *
     * @param fName The name of a Data-File that contains a serialized {@code java.lang.Object}
     *
     * @param ZIP if this is {@code TRUE}, it is assumed that the Data-File contains a
     * Zip-Compressed {@code Object}
     *
     * @return The {@code Object} that was written to the Data-File.
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or
     * disk operation.
     *
     * @throws ClassNotFoundException This exception is thrown when the Java Virtual
     * Machine (JVM) tries to load a particular class and the specified class cannot be found
     * in the {@code CLASSPATH}.
     */
    public static Object readObjectFromFile(String fName, boolean ZIP)
        throws IOException, ClassNotFoundException
    {
        // These stream's are 'java.lang.AutoCloseable'.
        //
        // NOTE: The IOException and ClassNotFoundException will still be thrown out of this
        //       method if they occur.  They are not caught!
        //
        // ALSO: In try-with-resources blocks, if there is a problem/exception, these
        //       classes are all (automatically) closed/flushed, in reverse order.

        try (
            FileInputStream     fis = new FileInputStream(fName);
            ObjectInputStream   ois = ZIP
                                    ? new ObjectInputStream(new GZIPInputStream(fis))
                                    : new ObjectInputStream(fis);
        )
            { return ois.readObject(); }
    }

    /**
     * Convenience Method.
     * <BR />Invokes: {@link #readObjectFromFile(String, Class, boolean)}
     * <BR />Catches Exception
     */
    public static <T> T readObjectFromFileNOCNFE(String fName, Class<T> c, boolean ZIP)
        throws IOException
    {
        try
            { return readObjectFromFile(fName, c, ZIP); }

        catch (ClassNotFoundException cnfe) { return null; }
    }

    /**
     * Reads an {@code Object} from a Data-File which must contain a serialized
     * {@code java.lang.Object}.
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_1OBJ_FILE>
     *
     * @param fName The name of a Data-File that contains a serialized {@code java.lang.Object}
     *
     * @param c This is the type of the {@code Object} expecting to be read from disk.  A value
     * for this parameter can always be obtained by referencing the {@code static} field
     * {@code '.class'} which is attached to <I>every object</I> in java.
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_CLASS_T>
     * 
     * @param <T> This should be set to the return type of this method.  By passing the expecred
     * return-type class, you may conveniently avoid having to cast the returned instance, or worry
     * about suppressing compiler warnings.
     * 
     * @param ZIP if this is {@code TRUE}, it is assumed that the Data-File contains a
     * Zip-Compressed {@code Object}
     *
     * @return The {@code Object} that was read from the Data-File.
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or disk
     * operation.
     *
     * @throws ClassNotFoundException This exception is thrown when the Java Virtual
     * Machine (JVM) tries to load a particular class and the specified class cannot be found in
     * the {@code CLASSPATH}.
     */
    public static <T> T readObjectFromFile(String fName, Class<T> c, boolean ZIP)
        throws IOException, ClassNotFoundException
    {
        Object o = readObjectFromFile(fName, ZIP);

        if (o == null)          return null;
        if (c.isInstance(o))    return c.cast(o);

        throw new ClassNotFoundException(
            "Although an object was indeed read from the file you have named [" + fName + "], " +
            "that object was not an instance of [" + c.getName() + "], " + 
            "but rather of [" + o.getClass().getName() + "]"
        );
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // read ALL OBJECTS FromFile
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * Convenience Method.
     * <BR />Invokes: {@link #readAllObjects(Class, Collection, String, boolean)}
     * <BR />Passes: {@code Object.class} to {@code 'objType'}
     * <BR />Passes: Newly instantiated {@code Vector<Object>} to {@code 'collection'}
     */
    public static Vector<Object> readAllObjectsToVector(String fName, boolean ZIP)
        throws IOException, ClassNotFoundException
    { return readAllObjects(Object.class, new Vector<Object>(), fName, ZIP); }

    /**
     * Convenience Method.
     * <BR />Invokes: {@link #readAllObjects(Class, Collection, String, boolean)}
     * <BR />Passes: Newly instantiated {@code Vector<T>} to {@code 'collection'}
     */
    public static <T> Vector<T> readAllObjectsToVector(Class<T> objType, String fName, boolean ZIP)
        throws IOException, ClassNotFoundException
    { return readAllObjects(objType, new Vector<T>(), fName, ZIP); }

    /**
     * Reads all {@code Object's} found inside a Data-File.  This Data-File should contain only
     * java-serialized {@code java.lang.Object's}.
     *
     * @param objType <EMBED CLASS='external-html' DATA-FILE-ID=FRW_OBJTYPE_PARAM>
     * 
     * @param <T> This allows the programmer to inform this method what type of {@code Object's}
     * are stored in the Serialized Object File, specified by {@code 'fName'}.
     *
     * @param collection This should be the desired {@code Collection<E>} that the programmer
     * would like be populated with the instances of type {@code 'objType'} read from file
     * {@code 'fName'}.  Variable-Type parameter {@code 'E'} needs to be equal-to or an 
     * ancestor of {@code 'objType'}
     * 
     * @param <U> Merely for convenience, this method returns the {@code Collection} instance that
     * is passed (by parameter {@code 'Collection'}) as a result of this function.  Therefore, the
     * Type Parameter {@code 'U'} identifies the Return Type of this method.
     *
     * @param fName The name of a Data-File that contains serialized {@code Object's}
     *
     * @param ZIP if this is {@code TRUE}, it is assumed that the Data-File contains Zip-Compressed
     * objects
     *
     * @return A reference to the {@code Collection} that was passed to this method.
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or disk
     * operation.
     */
    public static <T, U extends Collection<T>> U readAllObjects
        (Class<T> objType, U collection, String fName, boolean ZIP)
        throws IOException, ClassNotFoundException
    {
        // Temporary Variable, used in both versions of this method
        Object o;

        // These stream's are 'java.lang.AutoCloseable'.
        //
        // NOTE: The IOException and ClassNotFoundException will still be thrown out of this
        //       method if they occur.  They are not caught!
        //
        // ALSO: In try-with-resources blocks, if there is a problem/exception, these
        //       classes are all (automatically) closed/flushed, in reverse order.

        if (ZIP)

            try (
                FileInputStream     fis = new FileInputStream(fName);
                GZIPInputStream     gis = new GZIPInputStream(fis);
                ObjectInputStream   ois = new ObjectInputStream(gis);
            )
            {  
                while ((o = ois.readObject()) != null)

                    if (objType.isInstance(o))
                        collection.add(objType.cast(o));

                    else throw new ClassNotFoundException(
                        "At least one of the objects in the serialized object file " +
                            "[" + fName + "], " +
                        "was not an instance of [" + objType.getName() + "], " +
                        "but rather [" + o.getClass().getName() + "]"
                    );
            }

            catch (EOFException eofe) { }

        else

            try (
                FileInputStream     fis = new FileInputStream(fName);
                ObjectInputStream   ois = new ObjectInputStream(fis);
            )
            {  
                while ((o = ois.readObject()) != null)

                    if (objType.isInstance(o))
                        collection.add(objType.cast(o));

                    else throw new ClassNotFoundException(
                        "At least one of the objects in the serialized object file " +
                            "[" + fName + "], " +
                        "was not an instance of [" + objType.getName() + "], " +
                        "but rather [" + o.getClass().getName() + "]"
                    );
            }

            catch (EOFException eofe) { }

        return collection;
    }

    /**
     * Convenience Method.
     * <BR />Invokes: {@link #readAllObjectsToStream(Class, String, boolean)}
     * <BR />Passes: {@code Object.class} to {@code 'objType'}
     */
    public static Stream<Object> readAllObjectsToStream(String fName, boolean ZIP)
        throws IOException, ClassNotFoundException
    { return readAllObjectsToStream(Object.class, fName, ZIP); }

    /**
     * Reads all objects found inside a Data-File.  This Data-File should contain only
     * java-serialized {@code Object's}.
     *
     * @param fName The name of a Data-File that contains the serialized {@code Object's}
     *
     * @param objType This is the type of the {@code Object's} expecting to be read from disk.  A
     * value for this parameter can always be obtained by referencing the static field
     * {@code '.class'} which is attached to <I>every {@code Object}</I> in Java.  For instance, to
     * read a Data-File containing a series of {@code Date} instances, use {@code Date.class} as the
     * value to pass to this parameter.
     * 
     * @param <T> This parameter informs this method what type of Serialized Objects are saved
     * within {@code 'fName'}.  The Java {@code Stream} that is returned as a result of this method
     * will have the type {@code Stream<T>}.
     *
     * @param ZIP if this is {@code TRUE}, it is assumed that the Data-File contains Zip-Compressed
     * {@code Object's}
     *
     * @return A {@code Stream<T>} of all {@code Object's} found in the Data-File.  Converting
     * Java {@code Stream's} to other Data-Container types is as follows:
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=STREAM_CONVERT_T>
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or disk
     * operation.
     *
     * @throws ClassNotFoundException This exception is thrown when the Java Virtual
     * Machine (JVM) tries to load a particular class and the specified class cannot be found in
     * the classpath.
     */
    public static <T> Stream<T> readAllObjectsToStream(Class<T> objType, String fName, boolean ZIP)
        throws IOException, ClassNotFoundException
    {
        Stream.Builder<T>   b   = Stream.builder();
        Object              o   = null;

        try(
            FileInputStream fis = new FileInputStream(fName);

            ObjectInputStream ois = ZIP
                ? new ObjectInputStream(new GZIPInputStream(fis))
                : new ObjectInputStream(fis);
        )
        {
            while ((o = ois.readObject()) != null)

                if (objType.isInstance(o)) b.accept(objType.cast(o));

                else throw new ClassNotFoundException(
                    "At least one of the objects in the serialized object file [" + fName + "], " +
                    "was not an instance of [" + objType.getName() + "], " +
                    "but rather [" + o.getClass().getName() + "]"
                );
        }

        catch (EOFException eofe) { }

        return b.build();
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // Base-64 Read / Write Stuff (Text File)
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * Uses Java's {@code Object} serialization mechanism to serialize a {@code java.lang.Object},
     * and then uses the {@code Base64 String-MIME Encoding} system, also provided by java, to
     * convert the {@code Object} into a text-safe {@code java.lang.String} that may be viewed,
     * e-mailed, written to a web-page, etc.
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_1OBJ_FILE>
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_EXAMPLE_01>
     *
     * @param o This may be any serializable {@code java.lang.Object} instance.  It will be written
     * to a Text-File after first serializing the {@code Object}, and then next converting the
     * serialized data-bits to MIME-safe encoded text.
     *
     * @param fileName The fileName that will be used to save this {@code Object} as a Text-File.
     * 
     * @see #writeFile(CharSequence, String)
     * @see StringParse#objToB64MimeStr(Object)
     */
    public static void writeObjectToTextFile(Object o, String fileName)
        throws IOException
    { FileRW.writeFile(StringParse.objToB64MimeStr(o), fileName); }

    /**
     * This will read a java serialized, and MIME-Converted, MIME-Safe {@code java.lang.String}
     * from a text file and return the {@code Object} that it represented
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_1OBJ_FILE>
     *
     * @param fileName The name of the file containing the MIME-Encoded Serialized
     * {@code java.lang.Object}.
     *
     * @return The {@code Object} that had been encoded into the Text-File.
     * 
     * @see #loadFileToString(String)
     * @see StringParse#b64MimeStrToObj(String)
     */
    public static Object readObjectFromTextFile(String fileName) throws IOException
    { return StringParse.b64MimeStrToObj(loadFileToString(fileName)); }

    /**
     * Convenience Method.
     * <BR />Invokes: {@link #readObjectFromTextFile(String, Class)}
     * <BR />Catches Exception
     */
    public static <T> T readObjectFromTextFileNOCNFE(String fileName, Class<T> c)
        throws IOException
    {
        try
            { return readObjectFromTextFile(fileName, c); }

        catch (ClassNotFoundException cnfe) { return null; }
    }

    /**
     * This will read a java serialized, and MIME-Converted, MIME-Safe {@code java.lang.String}
     * from a text file and return the {@code Object} that it represented
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_1OBJ_FILE>
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_EXAMPLE_01>
     *
     * @param fileName The name of the file containing the MIME-Encoded Serialized
     * {@code java.lang.Object}.
     *
     * @param c This is the type of the {@code Object} expecting to be read from disk.  A value
     * for this parameter can always be obtained by referencing the {@code static} field
     * {@code '.class'}, which is attached to <I>every {@code Object}</I> in java.
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=FRW_CLASS_T>
     * 
     * @param <T> This Type Parameter informs this method what type of Base-64 Serialized Object
     * is saved within Text File {@code 'fileName'}.  The returned result of this method will have
     * this type, for convenience to avoid casting the {@code Object} (<I>unless that
     * {@code Object} is a Java Generic, and you wish to avoid a "Raw Types" warning</I>.  See 
     * further details inside the explanation about parameter {@code 'c'}).
     *
     * @return The {@code Object} that had been encoded into the Text-File.
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or disk
     * operation.
     *
     * @throws ClassNotFoundException This exception is thrown when the Java Virtual
     * Machine (JVM) tries to load a particular class and the specified class cannot be found in
     * the {@code CLASSPATH}.
     * 
     * @see StringParse#b64MimeStrToObj(String)
     * @see #loadFileToString(String)
     */
    public static <T> T readObjectFromTextFile(String fileName, Class<T> c)
        throws IOException, ClassNotFoundException
    { 
        Object o = StringParse.b64MimeStrToObj(loadFileToString(fileName));

        if (o == null)          return null;
        if (c.isInstance(o))    return c.cast(o);

        throw new ClassNotFoundException(
            "Although an object was indeed read from the file you have named [" + fileName + "], " +
            "that object was not an instance of [" + c.getName() + "], " + 
            "but rather of [" + o.getClass().getName() + "]"
        );
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // Object Input & Object Output Streams
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * Creates a simple {@code ObjectInputStream} - usually if multiple {@code Object's} have been
     * written to a single file.  It was better practice to put {@code Object's} in a
     * {@code java.util.Vector}, and write one {@code java.util.Vector} during serialization.
     * 
     * <BR /><BR />This, eventually, can became inadequate when downloading large numbers of HTML
     * results, where the need to write a large Data-File (intermittently - by saving intermediate
     * results) is needed.
     *
     * @param fName This is the File-Name of the Data-File where the serialized {@code Object's}
     * have been stored.
     *
     * @param ZIP If this is set to {@code TRUE}, the data will be de-compressed.
     *
     * @return A java {@code ObjectInputStream}
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System
     * or disk operation.
     */
    public static ObjectInputStream getOIS(String fName, boolean ZIP) throws IOException
    {
        return ZIP
            ? new ObjectInputStream(new GZIPInputStream(new FileInputStream(new File(fName))))
            : new ObjectInputStream(new FileInputStream(new File(fName))); 
    }

    /**
     * Creates a simple {@code ObjectOutputStream} - usually if multiple {@code Object's} need
     * to be written to a single file.  It was better practice to put {@code Object's} in a
     * {@code java.util.Vector}, and write one {@code java.util.Vector} during serialization.
     *
     * @param fName This is the File-Name of the Data-File where the serialized {@code Object's}
     * will be stored.
     *
     * @param ZIP If this is set to {@code TRUE}, the data will be compressed.
     *
     * @return A java {@code ObjectInputStream}
     *
     * @throws IOException If an I/O error has occurred as a result of the File-System or
     * disk operation.
     */
    public static ObjectOutputStream getOOS(String fName, boolean ZIP) throws IOException
    {
        return ZIP
            ? new ObjectOutputStream(new GZIPOutputStream(new FileOutputStream(new File(fName))))
            : new ObjectOutputStream(new FileOutputStream(new File(fName))); 
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // Copy, Move, Delete
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * This method will perform a byte-for-byte copy of a file from one location to another.
     *
     * @param inFileName The name of the input-file.  It will be byte-for-byte copied to an output
     * File-Name.
     *
     * @param outFileOrDirName The name of the output-file, or the name of the directory where the
     * file shall be moved.
     * 
     * <BR /><BR />If this file already exists <I>and it is a file (not a directory)</I>
     * it will be over-written.
     * 
     * <BR /><BR />If parameter {@code 'outFileOrDirName'} names a directory - <I>due
     * to having an ending {@code File.separator}</I>, <B>but</B> does not appear to name a
     * directory that exists, this method will throw a {@code FileNotFoundException}.
     * 
     * <BR /><BR />This can be avoided, however, by passing {@code TRUE} to parameter
     * {@code 'createDirsIfNotExist'}.  If {@code 'outFileOrDirName'} specifies a directory (by
     * virtue of the fact that it ends with the {@code File.separator String}) - <I>and 
     * {@code 'createDirsIfNotExist'} is {@code TRUE}</I>, then this method will first create any
     * and all sub-directories needed using the standard Java's {@code File.mkdirs()} method before
     * copying the file.
     * 
     * <BR /><BR /><DIV CLASS=JDHint>
     * <B><SPAN STYLE="color: red;">Summary:</SPAN></B> The programmer may provide either a
     * Directory-Name or a File-Name to parameter {@code 'outFileOrDirName'}.  If a Directory-Name
     * was provided, the moved file will <B>keep its name</B> - having the same name as the
     * original file, ({@code 'inFileName'}) had (but have been copied to directory
     * {@code 'outFileOrDirName'}).
     * </DIV>
     *
     * <BR /><DIV CLASS=JDHintAlt>
     * <B STYLE="color: red;">Behavior Note:</B> The behavior of this copy operation is generally /
     * mostly the same as the standard {@code UNIX} or {@code MS-DOS} commands {@code 'cp'} and
     * {@code 'copy'} (respectively) - <B>differing only in this method's ability to have
     * directories created using {@code File.mkdirs()}</B>
     * </DIV>
     *
     * @param createDirsIfNotExist If the target output-file is situated in a directory-path that
     * does not exist, this method will throw an exception.  However, if this boolean parameter is
     * set to {@code TRUE} and the aforementioned situation occurs where the complete-directory
     * tree does not exist, then this method will first attempt to create the directories using
     * {@code java.io.File.mkdirs().}
     *
     * @throws SecurityException If boolean parameter {@code 'createDirsIfNotExist'} is
     * {@code TRUE} <I>and if</I> the directory named by parameter {@code 'outFileName'} does not
     * exist, <I>and if</I> attempting to create such a directory is not permitted by the
     * Operating-System, then this exception shall throw.
     *
     * @throws IOException For any number of fail-causes in reading or writing input stream data.
     * An explanation of all causes of such an operation is beyond the scope of this
     * method-documentation entry.
     *
     * @throws FileNotFoundException If the {@code 'inFileName'} is not found, or
     * {@code 'outFileOrDirName'} uses a directory path that doesn't exist on the File-System,
     * <B>and</B> parameter {@code 'createDirsIfNotExist'} is set to {@code FALSE}.
     * 
     * @throws SameSourceAndTargetException This exception will be thrown if the <CODE>Java Virtual
     * Machine</CODE> ascertains that the source and target locations point to the same physical
     * disk locations.  The classes utilized for this operation are from package
     * {@code java.nio.file.*};
     * 
     * @throws InvalidPathException If the <I>Java Virtual Machine</I> is unable to instantiate an
     * instance of {@code java.nio.files.Path} for either the {@code 'inFileName'} parameter or the
     * {@code 'outFileOrDirName'}, then this exception will be thrown.
     * 
     * @throws NoSuchFileException If, after instantiating an instance of {@code Path} for either
     * the {@code source} or the {@code target} locations, the <I>Java Virtual Machine</I> is
     * unable to build an instance of {@code Path} using the method {@code Path.toRealPath()}, then
     * this exception will throw.
     */
    public static void copyFile
        (String inFileName, String outFileOrDirName, boolean createDirsIfNotExist)
        throws IOException
    {
        File f = new File(outFileOrDirName);

        if (createDirsIfNotExist) if (! f.exists()) f.mkdirs();

        if (f.isDirectory())
        {
            if (! outFileOrDirName.endsWith(File.separator))
                outFileOrDirName = outFileOrDirName + File.separator;

            outFileOrDirName = outFileOrDirName + StringParse.fromLastFileSeparatorPos(inFileName);
        }

        String inPath = Paths.get(inFileName).toRealPath().toString();
        // throws InvalidPathException
        // throws NoSuchFileException

        try
        {
            if (Paths.get(outFileOrDirName).toRealPath().toString().equals(inPath))

                throw new SameSourceAndTargetException(
                    "The Source File Name and the Target Location provided to your copyFile " +
                    "request operation appear to point to the same physical-disk location:\n" +
                    inPath
                );
        }

        catch (NoSuchFileException e) { }


        // NOTE: Mostly (but not always) the output file won't exist yet...  If it does not, 
        //       then we really don't need to worry about over-writing the origina file.
        // 
        // REMEMBER: The only purpose of the above test is to make sure that the source and
        //           target are not the same (to avoid clobbering the original file)

        FileInputStream     fis     = new FileInputStream(inFileName);
        FileOutputStream    fos     = new FileOutputStream(outFileOrDirName);
        byte[]              b       = new byte[5000];
        int                 result  = 0;

        try
            { while ((result = fis.read(b)) != -1) fos.write(b, 0, result); }

        finally
            { fis.close();  fos.flush();  fos.close(); }
    }

    /**
     * Convenience Method.
     * <BR />Invokes: {@code java.io.File.delete()}
     */
    public static void deleteFiles(String... fileNames)
    { for (String fileName : fileNames) (new File(fileName)).delete(); }

    /**
     * Convenience Method.
     * <BR />Invokes: {@link #copyFile(String, String, boolean)}
     * <BR />And-Then: deletes
     */
    public static void moveFile
        (String inFileName, String outFileName, boolean createDirsIfNotExist)
        throws IOException
    {
        copyFile(inFileName, outFileName, createDirsIfNotExist);
        (new File(inFileName)).delete();
    }

    /**
     * This deletes an entire directory, including any sub-directories.  It is like the UNIX
     * switch {@code -r} for the command {@code rm}, or the old Microsoft DOS Command
     * {@code 'deltree'} for deleting directories.  It simply reuses the class {@code FileTransfer}
     *
     * <BR /><BR /><B CLASS=JDDescLabel>Platform Independance (WORA):</B>
     * 
     * <BR />If this method is invoked from a UNIX or LINUX platform, then it will, generally,
     * bring about identical results as a call to {@link Shell#RM(String, String)} where the UNIX
     * {@code "-r"} (recursive) flag has been included / set.  On such a platform, an entire 
     * directory would be eliminated.
     * 
     * <BR /><BR />However, if executed from Windows, the class {@link Shell} would fail since it
     * only works on UNIX, but this method here would still succeed at its task.  It is a
     * "Platform-Independent" function.
     *
     * @param directoryName This should be a valid directory on the File-System.
     *
     * <BR /><BR /><DIV CLASS=JDHint>
     * <B STYLE="color: red">WARNING:</B> This command <B>does indeed delete the entire
     * Directory-Tree of the named directory!</B>
     * </DIV>
     * 
     * @param reCreateDirectoryOnExit This parameter allows the user to create an <I>an empty
     * directory with the same name</I> as the directory that was just deleted, after all of the
     * directory's contents have been deleted.  When this parameter is passed a value of
     * {@code TRUE}, the equivalent of the UNIX command {@code mkdir 'directoryName'} will be 
     * executed prior to exiting this method.
     * 
     * <BR /><BR />This can be a small convenience if the user desired that the directory be 
     * cleared, rather than deleted completely.
     *
     * @param log This parameter may be null, and if it is, it will be ignored.  This shall receive
     * textual log output from the deletion process.
     *
     * <EMBED CLASS='external-html' DATA-FILE-ID=APPENDABLE>
     *
     * @return This shall return a count on the total number of deleted files.  Note that when
     * directories are deleted (not files), their deletion <I>shall not count towards</I> the
     * total returned in this integer.
     *
     * @throws IllegalArgumentException Throws if the {@code String} provided to parameter
     * {@code directoryName} does not name a valid directory on the File-System.
     * 
     * @throws IOException May be thrown by the File-System Methods which underly this method.
     */
    public static int delTree
        (String directoryName, boolean reCreateDirectoryOnExit, Appendable log)
        throws IOException
    {
        if (directoryName == null) throw new NullPointerException
            ("You have provided null to parameter 'directoryName', but this is not allowed here.");

        File f = new File(directoryName);

        if (! f.exists()) throw new IllegalArgumentException(
            "The directory name you have provided: [" + directoryName + "] was not found on the " +
            "File System.  Aborted."
        );

        if (! f.isDirectory()) throw new IllegalArgumentException(
            "The value you have provided to parameter 'directoryName' was: " + 
            "[" + directoryName + "], but unfortunately this is not the name of a directory on " +
            "the File System, but rather a file.  This is not allowed here."
        );

        // Uses class FileNode to build the directory into Java Memory.
        // It is possibly of interest to note, that if running this java code on a UNIX or
        // LINUX platform, this method should perform the exact same operation as an invocation
        // of Shell.RM(directoryName, "-r");

        FileNode fn = FileNode.createRoot(directoryName).loadTree();

        int ret = FileTransfer.deleteFilesRecursive(fn, null, null, log);

        if (reCreateDirectoryOnExit) f.mkdirs();

        return ret;
    }

    /**
     * This may read a Text-File containing integer data.  If this data is a <B>Comma Separated
     * Value</B> {@code 'CSV'} Text-File, please pass {@code TRUE} to the parameter
     * {@code 'isCSV'}.  If this file contains integers that have commas between digits in groups
     * of three (like {@code '30,000'}) please pass {@code TRUE} to the parameter
     * {@code 'hasCommasInInts'}.
     * 
     * <EMBED CLASS='external-html' DATA-TYPE=int DATA-FILE-ID=FRW_READNUM_FFORMAT>
     * 
     * <BR /><BR /><DIV CLASS=JDHint>
     * <B STYLE='color: red;'>Number-Format:</B> The numbers in this Text-File must be parse-able
     * by Java class {@code java.lang.Integer} via its method
     * {@code Integer.parseInt(String s, int radix)}
     * </DIV>
     * 
     * @param fileName This should contain the File-Name which itself contains a list of integers.
     * These integers may be separated by either a comma ({@code ','}) or a space ({@code ' '}).
     * 
     * @param hasCommasInInts It is allowed that the file named by {@code 'fileName'} contain
     * integers which use the commonly found notation of having a comma between groups of three
     * digits within an integer.  For instance the number {@code '98765'}, to a reader, is often
     * represented as {@code '98,765'}.  When this parameter is set to {@code TRUE}, this method
     * shall simply remove any comma that is found juxtaposed between two digits before 
     * processing any text found in the file.
     * 
     * @param isCSV If the text file named by {@code 'fileName'} is a <B>Comma Separated Value</B>
     * file, then please pass {@code TRUE} to this parameter.  If {@code FALSE} is passed here,
     * then it is mandatory that the individual numbers inside the Text-File are separated by at
     * least one white-space character.
     * 
     * <BR /><BR /><DIV CLASS=JDHintAlt>
     * <B STYLE='color:red;'>Important:</B> If it is decided to set both of the boolean parameters
     * to {@code TRUE} - <I>where the integers have commas, <B STYLE="color: red">and</B> the
     * integers are separated by commas</I>, it is up to the programmer to ensure that the
     * individual numbers, themselves, are <I>not only</I> separated by a comma, <I>but also</I>
     * separated by a space as well.
     * </DIV>
     *
     * @param radix This is the {@code 'radix'}, which is also usually called the number's 
     * {@code 'base'} that is to be used when parsing the numbers.  Since Java's {@code class
     * java.lang.Integer} is used to perform the parse, <I>both</I> the {@code 'radix'}, <I>and</I>
     * the data found in the Text-File must conform to the Java method
     * {@code Integer.parseInt(String s, int radix)}.
     * 
     * <BR /><BR /><DIV CLASS=JDHint>
     * This parameter may not be ignored.  If the numbers in the Text-File are to be interpreted as
     * standard {@code 'decimal'} (<I>Base 10</I>) numbers, then the user should simply pass the
     * constant {@code '10'} to this parameter.
     * </DIV>
     * 
     * @return This method shall return a {@code java.util.stream.IntStream} consisting of the
     * integers that were found within the Text-File provided by {@code 'fileName'}.
     * 
     * <BR /><BR /><DIV CLASS=JDHintAlt>
     * An instance of {@code IntStream} is easily converted to an {@code int[]} array using the
     * method {@code IntStream.toArray()}.
     * </DIV>
     * 
     * @throws FileNotFoundException If the file named by parameter {@code 'fileName'} is not
     * found or not accessible in the File-System, then this exception will throw.
     * 
     * @throws IOException This exception throws if there are any errors that occur while
     * reading this file from the File-System.
     * 
     * @throws NumberFormatException If any of the numbers read from the Text-File are not
     * properly formatted, then this exception shall throw.
     * 
     * @see StringParse#NUMBER_COMMMA_REGEX
     * @see StringParse#COMMA_REGEX
     * @see StringParse#WHITE_SPACE_REGEX
     */
    public static IntStream readIntsFromFile
        (String fileName, boolean hasCommasInInts, boolean isCSV, int radix)
        throws FileNotFoundException, IOException
    {
        FileReader          fr  = new FileReader(fileName);
        BufferedReader      br  = new BufferedReader(fr);
        IntStream.Builder   b   = IntStream.builder();
        String              s   = "";

        while ((s = br.readLine()) != null)
        {
            // Skip blank lines.
            if ((s = s.trim()).length() == 0) continue;

            // This line simply finds String-Matches that match "Digit,Digit" and replaces
            // such matches with "DigitDigit".  After this replacement, they are parsed with ease.
            // NOTE: NUMBER_COMMMA_REGEX = Pattern.compile("\\d,\\d");

            if (hasCommasInInts)
                s = StringParse.NUMBER_COMMMA_REGEX.matcher(s).replaceAll("$1$2").trim();

            String[] numbers = isCSV
                ? StringParse.COMMA_REGEX.split(s)
                : StringParse.WHITE_SPACE_REGEX.split(s);
 
            for (String number : numbers)

                if ((number = number.trim()).length() > 0)
                    b.accept(Integer.parseInt(number, radix));
        }

        br.close();
        fr.close();
        return b.build();
    }

    /**
     * This may read a Text-File containing integer data.  If this data is a <B>Comma Separated
     * Value</B> {@code 'CSV'} Text-File, please pass {@code TRUE} to the parameter
     * {@code 'isCSV'}.  If this file contains integers that have commas between digits in groups
     * of three (like {@code '30,000'}) pleas pass {@code TRUE} to the parameter
     * {@code 'hasCommasInLongs'}.
     * 
     * <EMBED CLASS='external-html' DATA-TYPE=long DATA-FILE-ID=FRW_READNUM_FFORMAT>
     * 
     * <BR /><BR /><DIV CLASS=JDHint>
     * <B STYLE='color: red;'>Number-Format:</B> The numbers in this Text-File must be parse-able
     * by Java class {@code class java.lang.Long} using the method
     * {@code Long.parseLong(String s, int radix)}
     * </DIV>
     * 
     * @param fileName This should contain the File-Name which itself contains a list of 
     * {@code 'long'} integers.  These {@code long} integers may be separated by either a comma
     * ({@code ','}) or a space ({@code ' '}).
     * 
     * @param hasCommasInLongs It is allowed that the file named by {@code 'fileName'} contain
     * {@code long}-integers which use the commonly found notation of having a comma between groups
     * of three digits within a {@code long} integer.  For instance the number {@code '98765'}, to
     * a reader, is often represented as {@code '98,765'}.  When this parameter is set to
     * {@code TRUE}, this method shall simply remove any comma that is found juxtaposed between
     * two digits before processing any text found in the file.
     *
     * @param isCSV If the text file named by {@code 'fileName'} is a <B>Comma Separated Value</B>
     * file, then please pass {@code TRUE} to this parameter.  If {@code FALSE} is passed here,
     * then it is mandatory that the individual numbers inside the Text-File are separated by at
     * least one white-space character.
     * 
     * <BR /><BR /><DIV CLASS=JDHintAlt>
     * <B STYLE='color: red'>Important:</B> If it is decided to set both of the boolean parameters
     * to {@code TRUE} - <I>where the {@code long} integers have commas,
     * <B STYLE='color: red'>and</B> the {@code long} integers are separated by commas</I>, it is
     * up to the programmer to ensure that the individual numbers, themselves, are <I>not only</I> 
     * separated by a comma, <I>but also</I> separated by a space as well.
     * </DIV>
     * 
     * @param radix This is the {@code 'radix'}, which is also usually called the number's 
     * {@code 'base'} that is to be used when parsing the numbers.  Since Java's {@code class
     * Long} is used to perform the parse, <I>both</I> the {@code 'radix'}, <I>and</I> the data
     * found in the Text-File must conform to the Java method
     * {@code Long.parseLong(String s, int radix)}.
     * 
     * <BR /><BR /><DIV CLASS=JDHint>
     * This parameter may not be ignored.  If the numbers in the Text-File are to be interpreted as
     * standard {@code 'decimal'} (<I>Base 10</I>) numbers, then the user should simply pass the
     * constant {@code '10'} to this parameter.
     * </DIV>
     * 
     * @return This method shall return a {@code java.util.stream.LongStream} consisting of the
     * {@code long}-integers that were found within the Text-File provided by {@code 'fileName'}.
     * 
     * <BR /><BR /><DIV CLASS=JDHintAlt>
     * An instance of {@code LongStream} is easily converted to a {@code long[]} array using the
     * method {@code LongStream.toArray()}.
     * </DIV>
     * 
     * @throws FileNotFoundException If the file named by parameter {@code 'fileName'} is not
     * found or not accessible in the File-System, then this exception will throw.
     * 
     * @throws IOException This exception throws if there are any errors that occur while
     * reading this file from the File-System.
     * 
     * @throws NumberFormatException If any of the numbers read from the Text-File are not
     * properly formatted, then this exception shall throw.
     * 
     * @see StringParse#NUMBER_COMMMA_REGEX
     * @see StringParse#COMMA_REGEX
     * @see StringParse#WHITE_SPACE_REGEX
     */
    public static LongStream readLongsFromFile
        (String fileName, boolean hasCommasInLongs, boolean isCSV, int radix)
        throws FileNotFoundException, IOException
    {
        FileReader          fr  = new FileReader(fileName);
        BufferedReader      br  = new BufferedReader(fr);
        LongStream.Builder  b   = LongStream.builder();
        String              s   = "";

        while ((s = br.readLine()) != null)
        {
            // Skip blank lines.
            if ((s = s.trim()).length() == 0) continue;

            // This line simply finds String-Matches that match "Digit,Digit" and replaces
            // such matches with "DigitDigit".  After this replacement, they are parsed with ease.
            // NOTE: NUMBER_COMMMA_REGEX = Pattern.compile("\\d,\\d");

            if (hasCommasInLongs)
                s = StringParse.NUMBER_COMMMA_REGEX.matcher(s).replaceAll("$1$2").trim();

            String[] numbers = isCSV
                ? StringParse.COMMA_REGEX.split(s)
                : StringParse.WHITE_SPACE_REGEX.split(s);
 
            for (String number : numbers)
                if ((number = number.trim()).length() > 0)
                    b.accept(Long.parseLong(number, radix));
        }

        br.close();
        fr.close();
        return b.build();
    }

    /**
     * This may read a Text-File containing floating-point data.  If this data is a <B>Comma
     * Separated Value</B> {@code 'CSV'} Text-File, please pass {@code TRUE} to the parameter
     * {@code 'isCSV'}.  If this file contains {@code double's} that have commas between digits
     * in groups of three (like {@code '30,000,000,00'}) pleas pass {@code TRUE} to the parameter
     * {@code 'hasCommasInDoubles'}.
     *
     * <EMBED CLASS='external-html' DATA-TYPE=long DATA-FILE-ID=FRW_READNUM_FFORMAT>
     * 
     * <BR /><BR /><DIV CLASS=JDHint>
     * <B STYLE='color: red;'>Number-Format:</B> The numbers in this Text-File must be parse-able
     * by Java class {@code class java.lang.Double} using the method
     * {@code Double.parseDouble(String s)}
     * </DIV>
     * 
     * @param fileName This should contain the File-Name which itself contains a list of 
     * {@code 'double'} values.  These {@code double's} may be separated by either a comma
     * ({@code ','}) or a space ({@code ' '}).
     * 
     * @param hasCommasInDoubles It is allowed that the file named by {@code 'fileName'} contain
     * {@code double}-values which use the commonly found notation of having a comma between groups 
     * of three digits within a {@code double} value.  For instance the number {@code '98765.01'},
     * to a reader, can be represented as {@code '98,765.01'}.  When this parameter is set to
     * {@code TRUE}, this method shall simply remove any comma that is found juxtaposed between
     * two digits before processing any text found in the file.
     *
     * @param isCSV If the text file named by {@code 'fileName'} is a <B>Comma Separated Value</B>
     * file, then please pass {@code TRUE} to this parameter.  If {@code FALSE} is passed here,
     * then it is mandatory that the individual numbers inside the Text-File are separated by at
     * least one white-space character.
     * 
     * <BR /><BR /><DIV CLASS=JDHintAlt>
     * <B STYLE="color: red">Important:</B> If it is decided to set both of the boolean parameters
     * to {@code TRUE} - <I>where the {@code double} values have commas,
     * <B STYLE="color: red">and</B> the {@code double} values are separated by commas</I>, it is
     * up to the programmer to ensure that the individual numbers, themselves, are <I>not only</I> 
     * separated by a comma, <I>but also</I> separated by a space as well.
     * </DIV>
     * 
     * @return This method shall return a {@code java.util.stream.DoubleStream} consisting of the
     * {@code double}-values that were found within the Text-File provided by {@code 'fileName'}.
     * 
     * <BR /><BR /><DIV CLASS=JDHint>
     * An instance of {@code DoubleStream} is easily converted to a {@code double[]} array using
     * the method {@code DoubleStream.toArray()}.
     * </DIV>
     * 
     * @throws FileNotFoundException If the file named by parameter {@code 'fileName'} is not
     * found or not accessible in the File-System, then this exception will throw.
     * 
     * @throws IOException This exception throws if there are any errors that occur while
     * reading this file from the File-System.
     * 
     * @throws NumberFormatException If any of the numbers read from the Text-File are not
     * properly formatted, then this exception shall throw.
     * 
     * @see StringParse#NUMBER_COMMMA_REGEX
     * @see StringParse#COMMA_REGEX
     * @see StringParse#WHITE_SPACE_REGEX
     */
    public static DoubleStream readDoublesFromFile
        (String fileName, boolean hasCommasInDoubles, boolean isCSV)
        throws FileNotFoundException, IOException
    {
        FileReader              fr  = new FileReader(fileName);
        BufferedReader          br  = new BufferedReader(fr);
        DoubleStream.Builder    b   = DoubleStream.builder();
        String                  s   = "";

        while ((s = br.readLine()) != null)
        {
            // Skip blank lines.
            if ((s = s.trim()).length() == 0) continue;

            // This line simply finds String-Matches that match "Digit,Digit" and replaces
            // such matches with "DigitDigit".  After this replacement, they are parsed with ease.
            // NOTE: NUMBER_COMMMA_REGEX = Pattern.compile("\\d,\\d");

            if (hasCommasInDoubles)
                s = StringParse.NUMBER_COMMMA_REGEX.matcher(s).replaceAll("$1$2").trim();

            String[] numbers = isCSV
                ? StringParse.COMMA_REGEX.split(s)
                : StringParse.WHITE_SPACE_REGEX.split(s);
 
            for (String number : numbers)

                if ((number = number.trim()).length() > 0)
                    b.accept(Double.parseDouble(number));
        }

        br.close();
        fr.close();
        return b.build();
    }

    /**
     * Convenience Method.
     * <BR />Invokes: {@code java.io.FileOutputStream.write(byte[])}.
     * <BR /><B>NOTE:</B> This may throw {@code IOException, FileNotFoundException}, etc...
     */
    public static void writeBinary(byte[] bArr, String fileName) throws IOException
    {
        // The input-stream is  'java.lang.AutoCloseable'.
        //
        // NOTE: The IOException will still be thrown out of this method if it occurs.  It is not
        //       caught!  This also (potentially) throws SecurityException & FileNotFoundException

        try
            (FileOutputStream fos = new FileOutputStream(fileName))
            { fos.write(bArr); }
    }


    /**
     * Convenience Method.
     * <BR />Invokes: {@code java.io.FileOutputStream.write(byte[], int, int)}.
     * <BR /><B>NOTE:</B> This may throw {@code IOException, IndexOutOfBoundsException}, etc...
     */
    public static void writeBinary(byte[] bArr, int offset, int len, String fileName)
        throws IOException
    {
        // The input-stream is  'java.lang.AutoCloseable'.
        //
        // NOTE: The IOException will still be thrown out of this method if it occurs.  It is not
        //       caught!  This also (potentially) throws SecurityException, FileNotFoundException,
        //       IndexOutOfBoundsExcepton (if 'offset' or 'len' do not adhere to 'bArr' definition)

        try
            (FileOutputStream fos = new FileOutputStream(fileName))
            { fos.write(bArr, offset, len); }
    }

    /**
     * Convenience Method.
     * <BR />Invokes: {@link #readBinary(String, int, int)}.
     */
    public static byte[] readBinary(String fileName)
        throws FileNotFoundException, IOException
    { return readBinary(fileName, 0, -1); }

    /**
     * Reads data from a binary file into a Java {@code byte[]} array.
     * 
     * <BR /><BR />Unlike Java's {@code FileOutputStream.write(...)} method, the {@code read(...)}
     * Java provides in that same exact class is more difficult to use.  This method is much longer
     * than its corresponding {@link #writeBinary(byte[], String)} method.
     * 
     * @param fileName The name of the file (on the File-System) to read.
     * 
     * @param offset The number of {@code byte's} to skip before appending a {@code byte} into the
     * output {@code byte[]} array.  If the value provided to parameer {@code 'offset'} is longer
     * than the size of the file itself, then a <B>zero-length {@code byte[]} array</B> will be
     * returned.
     * 
     * <BR /><BR /><DIV CLASS=JDHint>
     * The meaning of the value in parameter {@code 'offset'} is very different from the meaning of
     * a parameter by that exact same name, except in method {@code read(...)} of class
     * {@code FileInputStream}.  <B>HERE</B> the offset is the number of <I>bytes to skip inside of
     * file {@code 'fileName'}, before saving the values that are read froom disk.</I>  In the
     * {@code FileInputStream}, offset is used as an array pointer.
     * </DIV>
     * 
     * @param len Once the internal-loop has begun copying bytes from the Data-File into the
     * returned {@code byte[]} array, {@code byte's} will continue to be copied into this array
     * until precisely {@code 'len'} bytes have been copied.
     * 
     * <BR /><BR /><DIV CLASS=JDHintAlt>
     * The user may provide any negative number to this parameter, and the read process will simply
     * begin at position {@code 'offset'}, and continue reading until the End of the File has been
     * reached.
     * </DIV>
     * 
     * @return Returns a {@code byte[]}-array, with a length of (parameter) {@code 'len'} bytes.
     * 
     * @throws FileNotFoundException Class {@code java.io.FileInputStream} will throw a
     * {@code FileNotFoundException} if that class is passed a {@code 'fileName'} that does not
     * exist, or is a File-Name that represents a directory not a file.
     * 
     * @throws SecurityException If a security manager exists and its {@code checkRead} method
     * denies read access to the file.
     * 
     * @throws IOException The {@code FileInputStream} instance, and the {@code java.io.File}
     * instance are both capable of throwing {@code IOException}.
     * 
     * @throws IllegalArgumentException
     * 
     * <BR /><BR /><UL CLASS=JDUL>
     * <LI> The value provided to {@code 'offset'} is negative</LI>
     * <LI> The value provided to parameter {@code 'len'} is zero.</LI>
     * </UL>
     * 
     * @throws FileSizeException This exception throws if any of the following are detected:
     * 
     * <BR /><BR /><UL CLASS=JDUL>
     * 
     * <LI> The returned {@code byte[]} array cannot have a size larger than
     *      {@code Integer.MAX_VALUE}.  If the returned array would have a larger size - <I>based
     *      on any combination of provided input values</I>, then this exception will throw.
     *      <BR /><BR />
     *      </LI>
     * 
     * <LI> The value provided to {@code 'offset'} is larger than the size of the underlying
     *      file that is specified by parameter {@code 'fileName'}
     *      <BR /><BR />
     *      </LI>
     * 
     * <LI> The total of {@code offset + len} is larger than the size of the underlying file.
     *      <BR /><BR />
     *      </LI>
     * 
     * <LI> An invocation of the method {@code File.length()} returns zero, indicating that the
     *      file is either unreadable, non-existant, or possibly empty.
     *      </LI>
     * 
     * </UL>
     * 
     * @throws EOFException This particular exception should not be expected.  Before any reads are
     * done, the size of the Data-File is first checked to see if it is big enough to have the
     * amount of data that is requested by input paramters {@code 'offset'} and {@code 'len'}.  If
     * however, an error occurrs, and the Operating System returns an {@code EOF} earlier than 
     * expected (for unforseen reasons), then {@code EOFException} would throw.
     */
    public static byte[] readBinary(String fileName, int offset, int len)
        throws FileNotFoundException, IOException
    {
        // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
        // EXCEPTION CHECKS
        // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***

        if (offset < 0) throw new IllegalArgumentException
            ("The value of offset (" + offset + ") is negative.");

        if (len == 0) throw new IllegalArgumentException
            ("A value of zero was provided to parameter 'len.'  This is not allowed");

        File f = new File(fileName);

        try
            (FileInputStream fis = new FileInputStream(f))
        {
            long fileLen = f.length();

            // A file-name that points to a completely empty file was passed to parameter 'fileName'
            // **OR** the operating system returned 0 for some other error-related reason.
            // According to the Java-Doc explanation, a '0' returned value might mean there were
            // errors when trying to access the file.

            if (fileLen == 0) throw new FileSizeException(
                "Calling java.io.File.length() returned 0 for the file-name that was " +
                "provided to this method:\n[" + fileName + "].  This might mean that the file " +
                "does not exist, or has other issues.",

            );

            // The file would end before we have even started reading bytes - after having skipped
            // 'offset' nmber of initial bytes.

            if (offset > fileLen) throw new FileSizeException(
                "The value of offset (" + offset + ") is larger than the size of the binary " +
                "file, which only had size (" + fileLen + ").",
                fileLen
            );

            // If 'len' was passed a negative value, that value is actually meaningless - and was
            // just used to indicate that reading the entire file starting at byte # 'offset' is
            // what the user is requesting.

            if (len > 0)

                // This simply checks how many bytes the file would need to have to provide for
                // reading from 'offset' up until 'offset + len'

                if ((offset + len) > fileLen) throw new FileSizeException(
                    "The file [" + fileName + "] apparently has a size of [" + fileLen + "], " +
                    "but the offset (" + offset + ") and the length (" +  len + ") that was " +
                    "requested sum to (" + (offset+len) + "), which is greater than that size.",
                    fileLen
                );


            // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
            // More Exception Checks: Check what the size of the returned byte[] array will be
            // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***

            // Negative-Length means that bytes are read until an EOF occurrs
            if (len < 0)
            {
                long bytesToRead = fileLen - offset;

                if (bytesToRead > Integer.MAX_VALUE) throw new FileSizeException(
                    "This file has [" + fileLen + "] bytes of data, and even with an offset of " +
                    '[' + offset + "], there are still " + bytesToRead + " bytes of data to " +
                    "place into the array.  This value is larger than Integer.MAX_VALUE " +
                    "(" + Integer.MAX_VALUE + ").",
                    fileLen
                );

                else len = (int) bytesToRead;
            }

            // A Positive length means that exactly the value inside input-parameter 'len' need to
            // be placed into the returned byte[] array.

            else if (len > Integer.MAX_VALUE) throw new FileSizeException(
                "This file has [" + fileLen + "] bytes of data, which is larger than " +
                "Integer.MAX_VALUE (" + Integer.MAX_VALUE + ").",
                fileLen
            );


            // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
            // FIRST, if there is a NON-ZERO OFFSET, then exactly OFFSET bytes must be skipped
            // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***

            int     failedReads         = 0;
            long    bytesSkipped        = 0;
            int     totalBytesSkipped   = 0;
            int     bytesRemaining      = offset;

            // NOTE: This loop is skipped, immediately / automatically, if indeed 'offset' is zero
            while (totalBytesSkipped < offset)

                if ((bytesSkipped = fis.skip(bytesRemaining)) == 0)
                {
                    if (failedReads++ == 10) throw new IOException(
                        "There have 10 repeated attempts to read the file's data, but all " +
                        "attempts have resulted in empty-reads with zero bytes being  retrieved " +
                        "from disk."
                    );
                }
                else
                {
                    // I don't see why this should happen, but it will be left here, just in
                    // case Java screws up.

                    if (bytesSkipped > bytesRemaining) throw new InternalError(
                        "This error is being thrown because the Java Virtual Machine has " +
                        "skipped past the end of the requested offset.  This has occured while " +
                        "calling FileInputStream.skip(offset)."
                    );

                    // NOTE: I am *FULLY AWARE* this is redundant, but the variable names are
                    //       the only thing that is very readable about this method.

                    totalBytesSkipped += bytesSkipped;
                    bytesRemaining -= bytesSkipped;
                }


            // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
            // THEN, Read the bytes from the file
            // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***

            byte[]  retArr      = new byte[len];
            int     arrPos      = 0;

            // This one was already defined / declared in the previous part.  Initialize it, but
            // don't re-declare it.
            bytesRemaining = len;

            // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
            // This loop exits when all (requested) bytes have been read, or EOFException!
            // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***

            while (bytesRemaining > 0)
            {
                int bytesRead = fis.read(retArr, arrPos, bytesRemaining);


                // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
                // Case 1: The EOF Marker was reached, before filling up the response-array
                // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***

                if (bytesRead == -1) if (bytesRemaining > 0) throw new EOFException(
                    "The end of file '" + fileName + "' was reached before " + len +
                    " bytes were read.  Only " + arrPos + " bytes were read."
                );


                // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
                // Yes, this seems redundant, but it's just the way it is
                // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
                // 
                // arrPos           ==>  0 ... retArr.length (retArr.length => input-param 'len')
                // bytesRemaining   ==>  'len' ... 0

                arrPos          += bytesRead;
                bytesRemaining  -= bytesRead;


                // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
                // Case 2: Exactly the appropriate number of bytes were read.
                // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***

                if (arrPos == retArr.length) return retArr;


                // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
                // Case 3: This should not be reachable!
                // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
                //
                // Java's FileInputStream.read method is supposed to stop when it has read
                // 'bytesRemaining' number of bytes!

                if (arrPos > retArr.length) throw new UnreachableError();
            }

            // One of the cases inside the loop body must fire before the loop ever actually exits,
            // unless I'm missing something!
            throw new UnreachableError();
        }
    }

    /**
     * Attempts to read a {@code java.lang.Class} from a class-file.
     * 
     * <BR /><BR />It is not neccessarily always knownst to the programmer what the
     * <I>Full-Package Class-Name</I>  of the {@code class} that's inside the class-file actually
     * is.
     * 
     * @param classFileName The name of any class-file on the File-System.
     * 
     * @param possibleClassNames If the exact <B STYLE='color: red;'>Full-Package Name</B> of the
     * class being read is known, then that ought to be the only {@code String} passed to this
     * Var-Args {@code String}-Parameter.  If there are multiple possibilities, pass all of them,
     * and all we be used in an attempt to parse &amp; load this class.
     * 
     * <BR /><BR /><B>DEVELOPER NOTE:</B> Perhaps I am stupid, but I cannot find any way (using the
     * standard JDK) to read a class file, and then ask that class-file either:
     * 
     * <BR /><BR /><UL CLASS=JDUL>
     * <LI>What the name of the {@code Class} in the Class-File is?</LI>
     * <LI>What the name of the {@code Package} being used in that Class-File is?</LI>
     * </UL>
     * 
     * <BR />So, for now, a Var-Args {@code String}-Array is required.
     * 
     * <BR /><BR />To add insult to injury, the standard Java Exception class
     * {@code 'TypeNotPresentException'} doesn't have a constructor that accepts a
     * {@code 'message'} parameter (it accepts a {@code 'typeName'}) parameter instead.  As a
     * result, if this method throws that exception, the error-message printed has a few 
     * 'extranneous characters' <B>BOTH</B> before the actual message, <B>AND</B> after it.  It is
     * staying this way because Java's Description of that exception matches precisely with its
     * use here.
     * 
     * @return An instance of {@code java.lang.Class} that was contained by the Class-File.
     * 
     * @throws IOException Java may throw several exceptions while attempting to load
     * the {@code '.class'} file into a {@code byte[]} array.  Such exceptions may include
     * {@code IOException}, {@code SecurityException}, {@code FileNotFoundException} etc...
     * 
     * @throws TypeNotPresentException If none of the names listed in Var-Args {@code String[]}
     * Array parameter {@code 'possibleClassNames'} are consistent with
     * <B STYLE='color:red'><I>BOTH</I></B> the package-name <B STYLE='color:red;'>AND</B> the
     * class-name of the actual class that resides inside {@code 'classFileName'}, then this 
     * exception will throw.
     * 
     * <BR /><BR /><DIV CLASS=JDHint>
     * <B STYLE='color:red'>Note:</B> Rather than simply returning 'null', this
     * {@code RuntimeException} is thrown as a nicely worded error message is provided.
     * </DIV>
     */
    public static Class<?> readClass(String classFileName, String... possibleClassNames)
        throws IOException
    {
        // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
        // Load the entire '.class' file into a byte[] array.
        // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***

        // Now read the bytes directly into a byte[] array, courtesy of Torello.Java.FileRW
        byte[] byteArray = readBinary(classFileName);


        // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
        // Create a ClassLoader - and convert "byte[]" into "Class<?> summarySorterClass"
        // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***

        // NOTE: The commented lines below will not work if there is a "Package Name" given to the
        //       class (in the '.java' file).  It is better to just read the raw class-file bytes 
        //       into a Java byte[] array.  SPECIFICALLY, if class is not inside of a directory
        //       that is PRECISELY-CONSISTENT with the full-path package+class name, then the class
        //       loader listed below will FAIL.  (NOTE: If the package+class name is consisten,
        //       then a programmer wouldn't need ANY OF THIS, and could simply call the normal
        //       "Class.forName(fullPackageClassName)" to get the class!)
        //
        // ClassLoader cl = new URLClassLoader(new URL[] { new URL("file://" + path) });
        // Class<?> ret = cl.loadClass(className);
        //
        // HOWEVER: Creating a new ClassLoader instance that accepts the byte-array (thereby
        //          exporting the 'protected' method defineClass) *DOES* work.

        class ByteClassLoader extends ClassLoader
        {
            public Class<?> defineClass(String name, byte[] classBytes)
            { return defineClass(name, classBytes, 0, classBytes.length); }
        }

        ByteClassLoader cl  = new ByteClassLoader();
        Class<?>        ret = null;
        StringBuilder   sb  = new StringBuilder();


        // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
        // Make attempts to convert the byte[] array into a java.lang.Class
        // *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***

        for (String fullClassName : possibleClassNames)

            try
                { return cl.defineClass(fullClassName, byteArray); }

            catch (NoClassDefFoundError e)
            {
                String errorMessage = e.getMessage();

                if (errorMessage != null) sb.append(errorMessage + '\n');
            }

        throw new TypeNotPresentException(
            "The Class-File: [" + classFileName  + "] seems to have been successfully read, but " +
            "none of the user provided Canonical-Class Names (including a package) were " +
            "consistent with the actual name of the Class/Type inside that class file.  Below " +
            "are listed the exception-messages received, which include both the actual/complete " +
            "canonical class-name, along with your user-provided guesses.  Errors Saved:\n" +
            StrIndent.indent(sb.toString(), 4),
            null
        );
    }
}