001package Torello.Java;
002
003/**
004 * Thrown when a <CODE>FileNode</CODE> operation has been invoked on an instance that represents
005 * an Operating-System <B><CODE>Directory</CODE></B>, but that invoked-method may only be applied
006 * to Operating-System <B><CODE>File</CODE></B> instances.  This is a {@code RuntimeException},
007 * not a checked-exception.
008 *
009 * <BR /><BR /><EMBED CLASS='external-html' DATA-FILE-ID=EXPM>
010 */
011public class FileExpectedException extends RuntimeException
012{
013    /** <EMBED CLASS='external-html' DATA-FILE-ID=SVUIDEX>  */
014    public static final long serialVersionUID = 1;
015
016    /**
017     * <EMBED CLASS='external-html' DATA-FILE-ID=EXPF>
018     * 
019     * <BR /><BR />This public final field contains the {@code FileNode} that caused an exception
020     * to throw.
021     */
022    public final FileNode fn;
023
024    /**
025     * Constructs a new exception with the specified detail message, and one {@code public, final} 
026     * parameter: {@code fn}.
027     * 
028     * @param message This is any message informing the user what has occurred.
029     * 
030     * @param fn This is the instance of {@code class FileNode} that was involved in the mistake.
031     * <EMBED CLASS='external-html' DATA-FILE-ID=EXPF_PARAM>
032     * 
033     * @throws ExceptionCheckError If parameter {@code 'fn'} is passed null
034     * 
035     * @see #fn
036     */
037    public FileExpectedException(String message, FileNode fn)
038    {
039        super(message);
040        this.fn = fn;
041
042        if (this.fn == null) throw new ExceptionCheckError
043            ("FileExpectedException constructor parameter 'fn' was passed null");
044    }
045
046    /**
047     * Constructs a new exception with the specified detail message, cause-chain 
048     * {@code Throwable}, and one {@code public, final} parameter: {@code fn}.
049     * 
050     * @param message This is any message informing the user what has occurred.
051     * 
052     * @param cause This parameter may be used when generating "multiple-exceptions" that are 
053     * modified as they are thrown.
054     * 
055     * @param fn This is the instance of {@code class FileNode} that was involved in the mistake.
056     * <EMBED CLASS='external-html' DATA-FILE-ID=EXPF_PARAM>
057     * 
058     * @throws ExceptionCheckError If parameter {@code 'fn'} is passed null
059     * 
060     * @see #fn
061     */
062    public FileExpectedException(String message, Throwable cause, FileNode fn)
063    {
064        super(message, cause);
065        this.fn = fn;
066
067        if (this.fn == null) throw new ExceptionCheckError
068            ("FileExpectedException constructor parameter 'fn' was passed null");
069    }
070
071    /**
072     * Checks whether or not the {@code FileNode} parameter passed is actually one representing a
073     * file, not a directory.
074     * 
075     * @param fn This may be any instance of {@code FileNode} however if it is not one that is
076     * meaning to represent an operating-system file, then this method will automatically throw an
077     * exception.
078     * 
079     * @throws FileExpectedException If parameter {@code 'fn'} is a file, not a directory.
080     */
081    public static void check(FileNode fn)
082    {
083        if (fn.isDirectory) throw new FileExpectedException(
084            "The invocation of the previous method on a FileNode that is, itself, a directory " +
085            "and not a file instead cannot proceed.",
086            fn
087        );
088    }
089}