org.geotools.util
Class Singleton

java.lang.Object
  java.util.AbstractCollection
      java.util.AbstractSet
          org.geotools.util.Singleton

All Implemented Interfaces:

java.util.Collection, java.util.Set

public class Singleton

extends java.util.AbstractSet

A mutable set containing only one element. This set can't contains null element.

Since:

2.1

Version:

$Id: Singleton.java 17672 2006-01-19 00:25:55Z desruisseaux $

Author:

Martin Desruisseaux

Constructor Summary

Singleton()
Creates a initially empty singleton.

Method Summary

boolean	add(java.lang.Object object) Adds the specified element to this set if it is not already present.
void	clear() Removes the element from this singleton.
boolean	contains(java.lang.Object object) Returns if this singleton contains the specified element.
java.lang.Object	get() Returns the element in this singleton.
boolean	isEmpty() Returns if this singleton contains no elements.
java.util.Iterator	iterator() Returns an iterator over the element of this singleton.
boolean	remove(java.lang.Object object) Removes the specified element from this singleton, if it is present.
int	size() Returns 1 if this singleton contains an element, or 0 otherwise.

Methods inherited from class java.util.AbstractSet

equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection

addAll, containsAll, retainAll, toArray, toArray, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Set

addAll, containsAll, retainAll, toArray, toArray

Constructor Detail

Singleton

public Singleton()

Creates a initially empty singleton.

Method Detail

size

public int size()

Returns 1 if this singleton contains an element, or 0 otherwise.

isEmpty

public boolean isEmpty()

Returns if this singleton contains no elements.

get

public java.lang.Object get()
                     throws java.util.NoSuchElementException

Returns the element in this singleton.

Returns:

The singleton element (never null).

Throws:

java.util.NoSuchElementException - if this singleton is empty.

contains

public boolean contains(java.lang.Object object)

Returns if this singleton contains the specified element.

add

public boolean add(java.lang.Object object)

Adds the specified element to this set if it is not already present. If this set already contains an other element, an exception is thrown.

Throws:

java.lang.NullPointerException - if the argument is null.

java.lang.IllegalArgumentException - if this set already contains an other element.

remove

public boolean remove(java.lang.Object object)

Removes the specified element from this singleton, if it is present.

clear

public void clear()

Removes the element from this singleton.

iterator

public java.util.Iterator iterator()

Returns an iterator over the element of this singleton.