Package com.google.common.collect

Class ForwardingList<E extends @Nullable Object>

java.lang.Object

com.google.common.collect.ForwardingObject

com.google.common.collect.ForwardingCollection<E>

com.google.common.collect.ForwardingList<E>

All Implemented Interfaces:

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

@GwtCompatible
public abstract class ForwardingList<E extends @Nullable Object>
extends ForwardingCollection<E>
implements List<E>

A list which forwards all its method calls to another list. Subclasses should override one or more methods to modify the behavior of the backing list as desired per the decorator pattern.

This class does not implement RandomAccess. If the delegate supports random access, the ForwardingList subclass should implement the RandomAccess interface.

Warning: The methods of ForwardingList forward indiscriminately to the methods of the delegate. For example, overriding add(int, E) alone will not change the behavior of addAll(int, java.util.Collection<? extends E>), which can lead to unexpected behavior. In this case, you should override addAll as well, either providing your own implementation, or delegating to the provided standardAddAll method.

default method warning: This class does not forward calls to default methods. Instead, it inherits their default implementations. When those implementations invoke methods, they invoke methods on the ForwardingList.

The standard methods and any collection views they return are not guaranteed to be thread-safe, even when all of the methods that they depend on are thread-safe.

Since:

2.0

Author:

Mike Bostock, Louis Wasserman

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ForwardingList()	Constructor for use by subclasses.

Method Summary

Modifier and Type	Method	Description
void	add(int index, E element)
boolean	addAll(int index, Collection<? extends E> elements)
protected abstract List<E>	delegate()	Returns the backing delegate instance that methods are forwarded to.
boolean	equals(@Nullable Object object)
E	get(int index)
int	hashCode()
int	indexOf(@Nullable Object element)
int	lastIndexOf(@Nullable Object element)
ListIterator<E>	listIterator()
ListIterator<E>	listIterator(int index)
E	remove(int index)
E	set(int index, E element)
protected boolean	standardAdd(E element)	A sensible default implementation of ForwardingCollection.add(Object), in terms of add(int, Object).
protected boolean	standardAddAll(int index, Iterable<? extends E> elements)	A sensible default implementation of addAll(int, Collection), in terms of the add method of listIterator(int).
protected boolean	standardEquals(@Nullable Object object)	A sensible definition of equals(Object) in terms of ForwardingCollection.size() and ForwardingCollection.iterator().
protected int	standardHashCode()	A sensible definition of hashCode() in terms of ForwardingCollection.iterator().
protected int	standardIndexOf(@Nullable Object element)	A sensible default implementation of indexOf(java.lang.Object), in terms of listIterator().
protected Iterator<E>	standardIterator()	A sensible default implementation of ForwardingCollection.iterator(), in terms of listIterator().
protected int	standardLastIndexOf(@Nullable Object element)	A sensible default implementation of lastIndexOf(java.lang.Object), in terms of listIterator(int).
protected ListIterator<E>	standardListIterator()	A sensible default implementation of listIterator(), in terms of listIterator(int).
protected ListIterator<E>	standardListIterator(int start)	A sensible default implementation of listIterator(int), in terms of ForwardingCollection.size(), get(int), set(int, Object), add(int, Object), and remove(int).
protected List<E>	standardSubList(int fromIndex, int toIndex)	A sensible default implementation of subList(int, int).
List<E>	subList(int fromIndex, int toIndex)

Methods inherited from class com.google.common.collect.ForwardingCollection

add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, standardAddAll, standardClear, standardContains, standardContainsAll, standardIsEmpty, standardRemove, standardRemoveAll, standardRetainAll, standardToArray, standardToArray, standardToString, toArray, toArray

Methods inherited from class com.google.common.collect.ForwardingObject

toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream, toArray

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface java.util.List

add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, replaceAll, retainAll, size, sort, spliterator, toArray, toArray

Constructor Detail

ForwardingList

protected ForwardingList()

Constructor for use by subclasses.

Method Detail

delegate

protected abstract List<E> delegate()

Description copied from class: ForwardingObject

Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such as ForwardingSet.delegate(). Concrete subclasses override this method to supply the instance being decorated.

Specified by:

delegate in class ForwardingCollection<E extends @Nullable Object>

add

public void add(int index,
                E element)

Specified by:

add in interface List<E extends @Nullable Object>

addAll

@CanIgnoreReturnValue
public boolean addAll(int index,
                      Collection<? extends E> elements)

Specified by:

addAll in interface List<E extends @Nullable Object>

get

public E get(int index)

Specified by:

get in interface List<E extends @Nullable Object>

indexOf

public int indexOf(@Nullable Object element)

Specified by:

indexOf in interface List<E extends @Nullable Object>

lastIndexOf

public int lastIndexOf(@Nullable Object element)

Specified by:

lastIndexOf in interface List<E extends @Nullable Object>

listIterator

public ListIterator<E> listIterator()

Specified by:

listIterator in interface List<E extends @Nullable Object>

listIterator

public ListIterator<E> listIterator(int index)

Specified by:

listIterator in interface List<E extends @Nullable Object>

remove

@CanIgnoreReturnValue
public E remove(int index)

Specified by:

remove in interface List<E extends @Nullable Object>

set

@CanIgnoreReturnValue
public E set(int index,
             E element)

Specified by:

set in interface List<E extends @Nullable Object>

subList

public List<E> subList(int fromIndex,
                       int toIndex)

Specified by:

subList in interface List<E extends @Nullable Object>

equals

public boolean equals(@Nullable Object object)

Specified by:

equals in interface Collection<E extends @Nullable Object>

Specified by:

equals in interface List<E extends @Nullable Object>

Overrides:

equals in class Object

hashCode

public int hashCode()

Specified by:

hashCode in interface Collection<E extends @Nullable Object>

Specified by:

hashCode in interface List<E extends @Nullable Object>

Overrides:

hashCode in class Object

standardAdd

protected boolean standardAdd(E element)

A sensible default implementation of ForwardingCollection.add(Object), in terms of add(int, Object). If you override add(int, Object), you may wish to override ForwardingCollection.add(Object) to forward to this implementation.

Since:

7.0

standardAddAll

protected boolean standardAddAll(int index,
                                 Iterable<? extends E> elements)

A sensible default implementation of addAll(int, Collection), in terms of the add method of listIterator(int). If you override listIterator(int), you may wish to override addAll(int, Collection) to forward to this implementation.

Since:

7.0

standardIndexOf

protected int standardIndexOf(@Nullable Object element)

A sensible default implementation of indexOf(java.lang.Object), in terms of listIterator(). If you override listIterator(), you may wish to override indexOf(java.lang.Object) to forward to this implementation.

Since:

7.0

standardLastIndexOf

protected int standardLastIndexOf(@Nullable Object element)

A sensible default implementation of lastIndexOf(java.lang.Object), in terms of listIterator(int). If you override listIterator(int), you may wish to override lastIndexOf(java.lang.Object) to forward to this implementation.

Since:

7.0

standardIterator

protected Iterator<E> standardIterator()

A sensible default implementation of ForwardingCollection.iterator(), in terms of listIterator(). If you override listIterator(), you may wish to override ForwardingCollection.iterator() to forward to this implementation.

Since:

7.0

standardListIterator

protected ListIterator<E> standardListIterator()

A sensible default implementation of listIterator(), in terms of listIterator(int). If you override listIterator(int), you may wish to override listIterator() to forward to this implementation.

Since:

7.0

standardListIterator

protected ListIterator<E> standardListIterator(int start)

A sensible default implementation of listIterator(int), in terms of ForwardingCollection.size(), get(int), set(int, Object), add(int, Object), and remove(int). If you override any of these methods, you may wish to override listIterator(int) to forward to this implementation.

Since:

7.0

standardSubList

protected List<E> standardSubList(int fromIndex,
                                  int toIndex)

A sensible default implementation of subList(int, int). If you override any other methods, you may wish to override subList(int, int) to forward to this implementation.

Since:

7.0

standardEquals

protected boolean standardEquals(@Nullable Object object)

A sensible definition of equals(Object) in terms of ForwardingCollection.size() and ForwardingCollection.iterator(). If you override either of those methods, you may wish to override equals(Object) to forward to this implementation.

Since:

7.0

standardHashCode

protected int standardHashCode()

A sensible definition of hashCode() in terms of ForwardingCollection.iterator(). If you override ForwardingCollection.iterator(), you may wish to override hashCode() to forward to this implementation.

Since:

7.0