org.geotools.util
Class DerivedSet

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

All Implemented Interfaces:

java.util.Collection, java.io.Serializable, java.util.Set

public abstract class DerivedSet

extends java.util.AbstractSet

implements java.io.Serializable

A set whose values are derived from an other set. The values are derived only when requested, which make it possible to backup potentially large sets. Implementations need only to overrides baseToDerived(java.lang.Object) and derivedToBase(java.lang.Object) methods. This set do not supports value, since is used when no mapping from base to exists. This class is serializable if the underlying base set is serializable too.

Since:

2.0

Version:

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

Author:

Martin Desruisseaux

See Also:

Serialized Form

Field Summary

protected java.util.Set

base The base set whose values are derived from.

Constructor Summary

DerivedSet(java.util.Set base)
Creates a new derived set from the specified base set.

Method Summary

boolean	add(java.lang.Object element) Ensures that this set contains the specified element.
protected abstract java.lang.Object	baseToDerived(java.lang.Object element) Transforms a value in the base set to a value in this set.
boolean	contains(java.lang.Object element) Returns if this set contains the specified element.
protected abstract java.lang.Object	derivedToBase(java.lang.Object element) Transforms a value in this set to a value in the base set.
boolean	isEmpty() Returns if this set contains no elements.
java.util.Iterator	iterator() Returns an iterator over the elements contained in this set.
boolean	remove(java.lang.Object element) Removes a single instance of the specified element from this set.
int	size() Returns the number of elements in this set.

Methods inherited from class java.util.AbstractSet

equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection

addAll, clear, 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, clear, containsAll, retainAll, toArray, toArray

Field Detail

base

protected final java.util.Set base

The base set whose values are derived from.

See Also:

baseToDerived(java.lang.Object), derivedToBase(java.lang.Object)

Constructor Detail

DerivedSet

public DerivedSet(java.util.Set base)

Creates a new derived set from the specified base set.

Parameters:

base - The base set.

Method Detail

baseToDerived

protected abstract java.lang.Object baseToDerived(java.lang.Object element)

Transforms a value in the base set to a value in this set. If there is no mapping in the derived set for the specified element, then this method returns .

Parameters:

element - A value in the base set.

Returns:

The value that this view should contains instead of , or .

derivedToBase

protected abstract java.lang.Object derivedToBase(java.lang.Object element)

Transforms a value in this set to a value in the base set.

Parameters:

element - A value in this set.

Returns:

The value stored in the base set.

iterator

public java.util.Iterator iterator()

Returns an iterator over the elements contained in this set. The iterator will invokes baseToDerived(java.lang.Object) for each element.

Specified by:

iterator in interface java.util.Set

Returns:

an iterator over the elements contained in this set.

size

public int size()

Returns the number of elements in this set. The default implementation counts the number of elements returned by the iterator.

Specified by:

size in interface java.util.Set

Returns:

the number of elements in this set.

isEmpty

public boolean isEmpty()

Returns if this set contains no elements.

Specified by:

isEmpty in interface java.util.Set

Returns:

if this set contains no elements.

contains

public boolean contains(java.lang.Object element)

Returns if this set contains the specified element. The default implementation invokes base.contains(derivedToBase(element)).

Specified by:

contains in interface java.util.Set

Parameters:

element - object to be checked for containment in this set.

Returns:

if this set contains the specified element.

add

public boolean add(java.lang.Object element)
            throws java.lang.UnsupportedOperationException

Ensures that this set contains the specified element. The default implementation invokes base.add(derivedToBase(element)).

Specified by:

add in interface java.util.Set

Parameters:

element - element whose presence in this set is to be ensured.

Returns:

if the set changed as a result of the call.

Throws:

java.lang.UnsupportedOperationException - if the base set doesn't supports the operation.

remove

public boolean remove(java.lang.Object element)
               throws java.lang.UnsupportedOperationException

Removes a single instance of the specified element from this set. The default implementation invokes base.remove(derivedToBase(element)).

Specified by:

remove in interface java.util.Set

Parameters:

element - element to be removed from this set, if present.

Returns:

if the set contained the specified element.

Throws:

java.lang.UnsupportedOperationException - if the base set doesn't supports the operation.