javolution37.javolution.lang

Interface Immutable

All Known Implementing Classes:

CharSet, Text

public interface Immutable

This interface identifies classes whose instances are not subject or susceptible to change or variation after creation. Once a class is declared immutable, any subclass must ensure immutability as well.

Immutable objects can safely be used in a multi-threaded environment and do not require defensive copying. For example:

     class Polygon implements Immutable {
          private List<Point2D> _vertices;
          public Polygon(List<Point2D> vertices) {
              _vertices = (vertices instanceof Immutable) ?
                   vertices : // Safe, the vertices cannot be modified by the client.
                   new FastTable<Point2D>(vertices); // Defensive copying required.
          }
     }

See Also:

Wikipedia: Immutable Object