org.cojen.util
Class WeakCanonicalSet<T>

java.lang.Object
  java.util.AbstractCollection<E>
      java.util.AbstractSet<T>
          org.cojen.util.WeakCanonicalSet<T>

All Implemented Interfaces:

Iterable<T>, Collection<T>, Set<T>

Direct Known Subclasses:

WeakFlyweightSet

public class WeakCanonicalSet<T>
extends AbstractSet<T>

A thread-safe Set that manages canonical objects: sharable objects that are typically immutable. Call the put method for supplying the WeakCanonicalSet with candidate canonical instances.

Objects that do not customize the hashCode and equals methods don't make sense to be canonicalized because each instance will be considered unique. The object returned from the put method will always be the same as the one passed in.

Author:

Brian S O'Neill

Constructor Summary

WeakCanonicalSet()

Method Summary

boolean	contains(Object obj)
protected boolean	equals(Object a, Object b)
protected int	hashCode(Object obj)
Iterator<T>	iterator()
<U extends T> U	put(U obj) Pass in a candidate canonical object and get a unique instance from this set.
int	size()
String	toString()

Methods inherited from class java.util.AbstractSet

equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection

add, addAll, clear, containsAll, isEmpty, remove, retainAll, toArray, toArray

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Set

add, addAll, clear, containsAll, isEmpty, remove, retainAll, toArray, toArray

Constructor Detail

WeakCanonicalSet

public WeakCanonicalSet()

Method Detail

put

public <U extends T> U put(U obj)

Pass in a candidate canonical object and get a unique instance from this set. The returned object will always be of the same type as that passed in. If the object passed in does not equal any object currently in the set, it will be added to the set, becoming canonical.

Parameters:

obj - candidate canonical object; null is also accepted

iterator

public Iterator<T> iterator()

Specified by:

iterator in interface Iterable<T>

Specified by:

iterator in interface Collection<T>

Specified by:

iterator in interface Set<T>

Specified by:

iterator in class AbstractCollection<T>

size

public int size()

Specified by:

size in interface Collection<T>

Specified by:

size in interface Set<T>

Specified by:

size in class AbstractCollection<T>

contains

public boolean contains(Object obj)

Specified by:

contains in interface Collection<T>

Specified by:

contains in interface Set<T>

Overrides:

contains in class AbstractCollection<T>

toString

public String toString()

Overrides:

toString in class AbstractCollection<T>

hashCode

protected int hashCode(Object obj)

equals

protected boolean equals(Object a,
                         Object b)