Package org.apache.commons.collections4.queue

Class UnmodifiableQueue<E>

java.lang.Object

org.apache.commons.collections4.collection.AbstractCollectionDecorator<E>

org.apache.commons.collections4.queue.AbstractQueueDecorator<E>

org.apache.commons.collections4.queue.UnmodifiableQueue<E>

Type Parameters:

E - The type of elements held in this queue

All Implemented Interfaces:

Serializable, Iterable<E>, Collection<E>, Queue<E>, Unmodifiable

public final class UnmodifiableQueue<E>
extends AbstractQueueDecorator<E>
implements Unmodifiable

Decorates another Queue to ensure it can't be altered.

Attempts to modify it will result in an UnsupportedOperationException.

Since:

4.0

See Also:

• Serialized Form

Method Summary

Modifier and Type	Method	Description
boolean	add(Object object)	Always throws UnsupportedOperationException.
boolean	addAll(Collection<? extends E> coll)	Always throws UnsupportedOperationException.
void	clear()	Always throws UnsupportedOperationException.
Iterator<E>	iterator()
boolean	offer(E obj)	Always throws UnsupportedOperationException.
E	poll()	Always throws UnsupportedOperationException.
E	remove()	Always throws UnsupportedOperationException.
boolean	remove(Object object)	Always throws UnsupportedOperationException.
boolean	removeAll(Collection<?> coll)	Always throws UnsupportedOperationException.
boolean	removeIf(Predicate<? super E> filter)	Always throws UnsupportedOperationException.
boolean	retainAll(Collection<?> coll)	Always throws UnsupportedOperationException.
static <E> Queue<E>	unmodifiableQueue(Queue<? extends E> queue)	Factory method to create an unmodifiable queue.

Methods inherited from class org.apache.commons.collections4.queue.AbstractQueueDecorator

decorated, element, peek

Methods inherited from class org.apache.commons.collections4.collection.AbstractCollectionDecorator

contains, containsAll, isEmpty, setCollection, size, toArray, toArray, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Collection

contains, containsAll, equals, hashCode, isEmpty, parallelStream, size, spliterator, stream, toArray, toArray

Methods inherited from interface java.lang.Iterable

forEach

Method Details

unmodifiableQueue

public static <E> Queue<E> unmodifiableQueue(Queue<? extends E> queue)

Factory method to create an unmodifiable queue.

If the queue passed in is already unmodifiable, it is returned.

Type Parameters:

E - The type of the elements in the queue

Parameters:

queue - The queue to decorate, must not be null

Returns:

An unmodifiable Queue

Throws:

NullPointerException - if queue is null

add

public boolean add(Object object)

Always throws UnsupportedOperationException.

Specified by:

add in interface Collection<E>

Specified by:

add in interface Queue<E>

Overrides:

add in class AbstractCollectionDecorator<E>

Parameters:

object - Ignored.

Throws:

UnsupportedOperationException - Always thrown.

addAll

public boolean addAll(Collection<? extends E> coll)

Always throws UnsupportedOperationException.

Specified by:

addAll in interface Collection<E>

Overrides:

addAll in class AbstractCollectionDecorator<E>

Parameters:

coll - Ignored.

Throws:

UnsupportedOperationException - Always thrown.

clear

public void clear()

Always throws UnsupportedOperationException.

Specified by:

clear in interface Collection<E>

Overrides:

clear in class AbstractCollectionDecorator<E>

Throws:

UnsupportedOperationException - Always thrown.

iterator

public Iterator<E> iterator()

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface Iterable<E>

Overrides:

iterator in class AbstractCollectionDecorator<E>

offer

public boolean offer(E obj)

Always throws UnsupportedOperationException.

Specified by:

offer in interface Queue<E>

Overrides:

offer in class AbstractQueueDecorator<E>

Parameters:

obj - Ignored.

Throws:

UnsupportedOperationException - Always thrown.

poll

public E poll()

Always throws UnsupportedOperationException.

Specified by:

poll in interface Queue<E>

Overrides:

poll in class AbstractQueueDecorator<E>

Throws:

UnsupportedOperationException - Always thrown.

remove

public E remove()

Always throws UnsupportedOperationException.

Specified by:

remove in interface Queue<E>

Overrides:

remove in class AbstractQueueDecorator<E>

Throws:

UnsupportedOperationException - Always thrown.

remove

public boolean remove(Object object)

Always throws UnsupportedOperationException.

Specified by:

remove in interface Collection<E>

Overrides:

remove in class AbstractCollectionDecorator<E>

Parameters:

object - Ignored.

Throws:

UnsupportedOperationException - Always thrown.

removeAll

public boolean removeAll(Collection<?> coll)

Always throws UnsupportedOperationException.

Specified by:

removeAll in interface Collection<E>

Overrides:

removeAll in class AbstractCollectionDecorator<E>

Parameters:

coll - Ignored.

Throws:

UnsupportedOperationException - Always thrown.

removeIf

public boolean removeIf(Predicate<? super E> filter)

Always throws UnsupportedOperationException.

Specified by:

removeIf in interface Collection<E>

Overrides:

removeIf in class AbstractCollectionDecorator<E>

Parameters:

filter - Ignored.

Throws:

UnsupportedOperationException - Always thrown.

Since:

4.4

retainAll

public boolean retainAll(Collection<?> coll)

Always throws UnsupportedOperationException.

Specified by:

retainAll in interface Collection<E>

Overrides:

retainAll in class AbstractCollectionDecorator<E>

Parameters:

coll - Ignored.

Throws:

UnsupportedOperationException - Always thrown.