Class WeakList<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

net.sourceforge.jnlp.util.WeakList<E>

Type Parameters:

E - generic typeto be used in this list

All Implemented Interfaces:

Iterable<E>, Collection<E>, List<E>, SequencedCollection<E>

public class WeakList<E>
extends AbstractList<E>

This list stores objects automatically using weak references. Objects are added and removed from the list as normal, but may turn to null at any point (ie, indexOf(x) followed by get(x) may return null). The weak references are only removed when the trimToSize method is called so that the indices remain constant otherwise.

Version:

$Revision: 1.3 $

Field Summary

Fields

Modifier and Type	Field	Description
private final ArrayList<WeakReference<E>>	refs

Fields inherited from class AbstractList

modCount

Constructor Summary

Constructors

Constructor	Description
WeakList()	Create a weak random-access list.

Method Summary

Modifier and Type	Method	Description
void	add(int index, E element)	Inserts the object at the specified position in the list.
private E	deref(WeakReference<E> o)	Extract the hard reference out of a weak reference.
E	get(int index)
List<E>	hardList()
E	remove(int index)	Removes the object at the specified position and returns it or returns null if it was already collected.
E	set(int index, E element)	Sets the object at the specified position and returns the previous object at that position or null if it was already collected.
int	size()
void	trimToSize()	Compacts the list by removing references to collected objects.

Methods inherited from class AbstractList

add, addAll, clear, equals, hashCode, indexOf, iterator, lastIndexOf, listIterator, listIterator, removeRange, subList

Methods inherited from class AbstractCollection

addAll, contains, containsAll, isEmpty, remove, removeAll, retainAll, toArray, toArray, toString

Methods inherited from class Object

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

Methods inherited from interface Collection

parallelStream, removeIf, stream, toArray

Methods inherited from interface Iterable

forEach

Methods inherited from interface List

addAll, addFirst, addLast, contains, containsAll, getFirst, getLast, isEmpty, remove, removeAll, removeFirst, removeLast, replaceAll, retainAll, reversed, sort, spliterator, toArray, toArray

Field Details

refs

private final ArrayList<WeakReference<E>> refs

Constructor Details

WeakList

public WeakList()

Create a weak random-access list.

Method Details

deref

private E deref(WeakReference<E> o)

Extract the hard reference out of a weak reference.

get

public E get(int index)

Specified by:

get in interface List<E>

Specified by:

get in class AbstractList<E>

Parameters:

index - of field to get

Returns:

the object at the specified index, or null if the object has been collected.

size

public int size()

Specified by:

size in interface Collection<E>

Specified by:

size in interface List<E>

Specified by:

size in class AbstractCollection<E>

Returns:

the size of the list, including already collected objects.

set

public E set(int index,
 E element)

Sets the object at the specified position and returns the previous object at that position or null if it was already collected.

Specified by:

set in interface List<E>

Overrides:

set in class AbstractList<E>

Parameters:

index - position where to place element

element - data which to put on position

Returns:

previous object on that position

add

public void add(int index,
 E element)

Inserts the object at the specified position in the list. Automatically creates a weak reference to the object.

Specified by:

add in interface List<E>

Overrides:

add in class AbstractList<E>

Parameters:

index - position where to insert element

element - data which to put on position

remove

public E remove(int index)

Removes the object at the specified position and returns it or returns null if it was already collected.

Specified by:

remove in interface List<E>

Overrides:

remove in class AbstractList<E>

Parameters:

index - of element to be removed

Returns:

previous object on that position

hardList

public List<E> hardList()

Returns:

a list of hard references to the objects. The returned list does not include the collected elements, so its indices do not necessarily correlate with those of this list.

trimToSize

public void trimToSize()

Compacts the list by removing references to collected objects.