javolution.lang

Interface Immutable<T>

Type Parameters:

T - The type of the immutable constant value.

All Known Subinterfaces:

ValueType<T>

All Known Implementing Classes:

CharSet, Index, QName, Text

public interface Immutable<T>

An object capable of returning a value not subject or susceptible of change or variation. For example, Immutable<List>> has a List value which is guaranteed to be constant (not modifiable by anybody). Classes implementing this interface do not need themselves to be unmodifiable. If the value and the class are the same, the ValueType sub-interface can be implemented.

 class Polygon extends Shape implements ValueType<Shape> { // extends Immutable<Shape>
     private List<Point2D> vertices;
     public Polygon(Immutable<List<Point2D>> vertices) { // Immutable<List> has a constant List value.
         this.vertices = vertices.value(); // No defensive copying required (vertices.value() is certified constant).
     }
     public Polygon value() { return this; } // As per ValueType contract.
 }

FastCollection/FastMap have direct support for immutable.

 Polygon triangle = new Polygon(new FastTable<Point2D>().addAll(p1, p2, p3).toImmutable());

Version:

6.0, July 21, 2013

Author:

Jean-Marie Dautelle

See Also:

Wikipedia: Immutable Object, FastCollection.toImmutable()

Method Summary

Methods

Modifier and Type	Method and Description
T	value() Returns the constant value held by this object.

Method Detail

value

T value()

Returns the constant value held by this object.