Package Torello.Java.Additional

Class MultiType

java.lang.Object

Torello.Java.Additional.MultiType

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable

Direct Known Subclasses:

RetN, TupleN

public abstract class MultiType
extends java.lang.Object
implements java.io.Serializable, java.lang.Cloneable

This is a parent class of the 'Multiple Return Type' classes. (Ret0 ... Ret8) This class provides some basic functionality to its descendants, namely: toString(), hashCode() and equals(Object).

See Also:

Serialized Form

Hi-Lited Source-Code:

• View Here: Torello/Java/Additional/MultiType.java
• Open New Browser-Tab: Torello/Java/Additional/MultiType.java

File Size: 11,559 Bytes Line Count: 277 '\n' Characters Found

Field Summary

Fields

Modifier and Type	Field
protected static long	serialVersionUID

Method Summary

Convenience Getters for SubClasses
Modifier and Type	Method
abstract Object	get(int i)
<T> T	get(int i, Class<T> c)
<T> T	GET(int i)
Convert Fields to Object Array
Modifier and Type	Method
Object[]	asArray()
Retrieve the Number of Fields in this Class
Modifier and Type	Method
abstract int	n()
Methods: interface java.lang.Cloneable
Modifier and Type	Method
abstract Object	clone()
Methods: class java.lang.Object
Modifier and Type	Method
boolean	equals(Object other)
int	hashCode()
String	toString()

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

serialVersionUID

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protected static final long serialVersionUID

This fulfils the SerialVersion UID requirement for all classes that implement Java's interface java.io.Serializable. Using the Serializable Implementation offered by java is very easy, and can make saving program state when debugging a lot easier. It can also be used in place of more complicated systems like "hibernate" to store data as well.

See Also:

Constant Field Values

Code:

Exact Field Declaration Expression:

 protected static final long serialVersionUID = 1;

Method Detail

n

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public abstract int n()

All implementations of this abstract can indicate which of the RetN or TupleN instances they are, by returning the number of fields they hold using this method.

Returns:

The number of fields contained by the class that is implementing 'this' instance. So for example, an instance of Tuple5 would produce '5', if this method were called; and Ret3 would produce '3', and so on and so forth.

asArray

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public java.lang.Object[] asArray()

Retrieve the contents of the instance-descendant class, as an array.

Returns:

Returns the 'this' instance' fields 'a', 'b', 'c' etc... as an Object[] array.

Code:

Exact Method Body:

 return asArrayMain();

get

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public abstract java.lang.Object get(int i)

This will return an instance of Object which represents the ith instance-field from whatever RetN or TupleN implementation this method has been invoked.

If 'this' instance were a Ret5, and '3' were passed to parameter 'i', then the value in Ret5.c would be returned.

If a call to 'get' is made from Tuple2, and '3' were passed to 'i', then an IndexOutOfBoundsException would throw.

Parameters:

i - This specifies which field of the instance is being requested.

Important: Unlike a Java array, when a '1' is passed to this parameter, it is requesting the first field in this instance. Passing a value of '0' shall cause an IndexOutOfBoundsException throw.

Returns:

This returns the ith field of this class.

Throws:

java.lang.IndexOutOfBoundsException - if 'i' is zero or negative, or greater than the value of 'N' for whichever RetN or TupleN class is being used.

If 'this' is an instance of Tuple5, then a value of 6 or greater would force this exception to throw.

See Also:

get(int, Class), GET(int)

get

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public final <T> T get(int i,
                       java.lang.Class<T> c)

This provides a quick way to cast the field to the requested class. This may be quicker typing than using an actual cast, because it will not generate a compiler warning about unchecked casts. If the cast fails, it will throw the usual ClassCastException.

Parameters:

i - This specifies which field of the implementing RetN is being requested.

Important: Unlike a Java array, when a '1' is passed to this parameter, it is requesting the first field in the RetN. Passing a value of '0' shall case an IndexOutOfBoundsException exception.

Returns:

This returns the ith field of this class.

Throws:

java.lang.IndexOutOfBoundsException - if 'i' is zero or negative, or greater than the value of 'N' for whichever RetN class is being used. If 'this' is an instance of Ret5, then a value of 6 or greater will cause this exception to throw.

java.lang.ClassCastException - If the field cannot be cast to the class provided.

See Also:

get(int), GET(int)

Code:

Exact Method Body:

 return c.cast(get(i));

GET

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public final <T> T GET(int i)

This is more magic with Java's Type-Inferencing being applied to a Generic-Cast. Note that this method works a lot like (but not identical to) the later Java 'var' syntax. Here, Java's Type-Inference Mechanism (inside the compile-time, not run-time, logic) will cast the result of this method to whatever type is on the left hand-side of the assignment.

Type-Inferencing: Remember that the Java-Compiler will output a Compile-Time Error if it appears that it cannot infer type-parameter 'T'.

Run-Time Casting: This method will throw a Run-Time 'ClassCastException', if the cast fails.

Type Parameters:

T - This Type-Parameter is inferred by whatever assignment is taking place, or however the result of this method is being applied, programatically. More can be read about Java's Compile-Time Type-Inferencing Mechanism on the Oracle Website.

Parameters:

i - This specifies which field of the implementing RetN is being requested.

Important: Unlike a Java array, when a '1' is passed to this parameter, it is requesting the first field in the RetN. Passing a value of '0' shall case an IndexOutOfBoundsException exception.

Returns:

This returns the ith field of this class.

Throws:

java.lang.IndexOutOfBoundsException - if 'i' is zero or negative, or greater than the value of 'N' for whichever RetN class is being used. If 'this' is an instance of Ret5, then a value of 6 or greater will cause this exception to throw.

java.lang.ClassCastException - If the ith field of this class cannot be cast to the type that is inferred for Type-Parameter 'T'.

Code:

Exact Method Body:

 return (T) get(i);

equals

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public boolean equals(java.lang.Object other)

Compares 'this' with another Java Object for equality.

Overrides:

equals in class java.lang.Object

Parameters:

other - Any Java Object.

Returns:

If 'this' instance is equal to the 'other' instance.

Code:

Exact Method Body:

 if (this == other) return true;

 if (! (other instanceof MultiType)) return false;

 MultiType o = (MultiType) other;

 if (o.n() != this.n()) return false;

 Object[] theseFields = asArray();
 Object[] thoseFields = o.asArray();


 // Keep this in mind - Three lines ago, the value of n() was already checked!
 // if (theseFields.length != thoseFields.length) throw new UnreachableError();

 for (int i=0; i < theseFields.length; i++)

     if (theseFields[i] == thoseFields[i])
         continue;

     else if (
                 ((theseFields[i] != null) && (thoseFields[i] != null))
                 &&
                 (theseFields[i].getClass() == thoseFields[i].getClass())
                 &&
                 theseFields[i].equals(thoseFields[i])
             )
         continue;

     else
         return false;

 return true;

hashCode

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public int hashCode()

Builds a hash-code to fulfill Java's java.lang.Object requirement. This variant of a hash function simply computes a hashcode for the first two non-null fields of this instance, and returns their sum.

If there aren't at least two non-null fields in this instance, then the hashcode for however many have been computed (READ: either 0, or 1) is returned.

Overrides:

hashCode in class java.lang.Object

Returns:

a hash-code that may be used for sets and maps like java.util.Hashtable and java.util.HashSet.

Code:

Exact Method Body:

 // This is the value returned.
 int hashCode    = 0;
 int count       = 0;

 for (Object field : asArray())

     if (field != null)
     {
         hashCode += field.hashCode();

         // Once two Hash Code's have been computed return the 'SUM' of them.
         if (++count == 2) return hashCode;
     }

 return hashCode;

toString

🡅 🡇 ⇈ ⮫ External-Java: ⮫ 🗕 🗗 🗖

public java.lang.String toString()

Converts this instance of the implementing RetN to a String.

Overrides:

toString in class java.lang.Object

Returns:

This instance-object as a String.

Code:

Exact Method Body:

 return MultiTypeToString.run(this.asArray(), this.n());

clone

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public abstract java.lang.Object clone()

Clones the contents of 'this' instance of.

Overrides:

clone in class java.lang.Object

Returns:

A clone copy of 'this' object.