Package com.google.common.collect

Class Sets.SetView<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractSet<E>

com.google.common.collect.Sets.SetView<E>

All Implemented Interfaces:

Iterable<E>, Collection<E>, Set<E>

Enclosing class:

Sets

public abstract static class Sets.SetView<E>
extends AbstractSet<E>

An unmodifiable view of a set which may be backed by other sets; this view will change as the backing sets do. Contains methods to copy the data into a new set which will then remain stable. There is usually no reason to retain a reference of type SetView; typically, you either use it as a plain Set, or immediately invoke immutableCopy() or copyInto(S) and forget the SetView itself.

Since:

2.0

Method Summary

Modifier and Type	Method	Description
boolean	add(E e)	Deprecated. Unsupported operation.
boolean	addAll(Collection<? extends E> newElements)	Deprecated. Unsupported operation.
void	clear()	Deprecated. Unsupported operation.
<S extends Set<E>> S	copyInto(S set)	Copies the current contents of this set view into an existing set.
ImmutableSet<E>	immutableCopy()	Returns an immutable copy of the current contents of this set view.
abstract UnmodifiableIterator<E>	iterator()	Scope the return type to UnmodifiableIterator to ensure this is an unmodifiable view.
boolean	remove(Object object)	Deprecated. Unsupported operation.
boolean	removeAll(Collection<?> oldElements)	Deprecated. Unsupported operation.
boolean	retainAll(Collection<?> elementsToKeep)	Deprecated. Unsupported operation.

Methods inherited from class java.util.AbstractSet

equals, hashCode

Methods inherited from class java.util.AbstractCollection

contains, containsAll, isEmpty, size, toArray, toArray, 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.Set

contains, containsAll, isEmpty, size, spliterator, toArray, toArray

Method Detail

immutableCopy

public ImmutableSet<E> immutableCopy()

Returns an immutable copy of the current contents of this set view. Does not support null elements.

Warning: this may have unexpected results if a backing set of this view uses a nonstandard notion of equivalence, for example if it is a TreeSet using a comparator that is inconsistent with Object.equals(Object).

copyInto

@CanIgnoreReturnValue
public <S extends Set<E>> S copyInto(S set)

Copies the current contents of this set view into an existing set. This method has equivalent behavior to set.addAll(this), assuming that all the sets involved are based on the same notion of equivalence.

Returns:

a reference to set, for convenience

add

@CanIgnoreReturnValue
@Deprecated
public final boolean add(E e)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

add in interface Collection<E>

Specified by:

add in interface Set<E>

Overrides:

add in class AbstractCollection<E>

Parameters:

e - element whose presence in this collection is to be ensured

Returns:

true if this collection changed as a result of the call

Throws:

UnsupportedOperationException - always

remove

@CanIgnoreReturnValue
@Deprecated
public final boolean remove(Object object)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

remove in interface Collection<E>

Specified by:

remove in interface Set<E>

Overrides:

remove in class AbstractCollection<E>

Parameters:

object - element to be removed from this collection, if present

Returns:

true if an element was removed as a result of this call

Throws:

UnsupportedOperationException - always

addAll

@CanIgnoreReturnValue
@Deprecated
public final boolean addAll(Collection<? extends E> newElements)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

addAll in interface Collection<E>

Specified by:

addAll in interface Set<E>

Overrides:

addAll in class AbstractCollection<E>

Parameters:

newElements - collection containing elements to be added to this collection

Returns:

true if this collection changed as a result of the call

Throws:

UnsupportedOperationException - always

See Also:

AbstractCollection.add(Object)

removeAll

@CanIgnoreReturnValue
@Deprecated
public final boolean removeAll(Collection<?> oldElements)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

removeAll in interface Collection<E>

Specified by:

removeAll in interface Set<E>

Overrides:

removeAll in class AbstractSet<E>

Parameters:

oldElements - collection containing elements to be removed from this set

Returns:

true if this set changed as a result of the call

Throws:

UnsupportedOperationException - always

See Also:

AbstractCollection.remove(Object), AbstractCollection.contains(Object)

retainAll

@CanIgnoreReturnValue
@Deprecated
public final boolean retainAll(Collection<?> elementsToKeep)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

retainAll in interface Collection<E>

Specified by:

retainAll in interface Set<E>

Overrides:

retainAll in class AbstractCollection<E>

Parameters:

elementsToKeep - collection containing elements to be retained in this collection

Returns:

true if this collection changed as a result of the call

Throws:

UnsupportedOperationException - always

See Also:

AbstractCollection.remove(Object), AbstractCollection.contains(Object)

clear

@Deprecated
public final void clear()

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

clear in interface Collection<E>

Specified by:

clear in interface Set<E>

Overrides:

clear in class AbstractCollection<E>

Throws:

UnsupportedOperationException - always

iterator

public abstract UnmodifiableIterator<E> iterator()

Scope the return type to UnmodifiableIterator to ensure this is an unmodifiable view.

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface Set<E>

Specified by:

iterator in class AbstractCollection<E>

Returns:

an iterator over the elements contained in this collection

Since:

20.0 (present with return type Iterator since 2.0)