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

Field Summary

Fields

Modifier and Type	Field	Description
private static final long	serialVersionUID	Serialization version

Constructor Summary

Constructors

Modifier	Constructor	Description
private	UnmodifiableQueue(Queue<? extends E> queue)	Constructor that wraps (not copies).

Method Summary

Modifier and Type	Method	Description
boolean	add(Object object)
boolean	addAll(Collection<? extends E> coll)
void	clear()
Iterator<E>	iterator()
boolean	offer(E obj)
E	poll()
private void	readObject(ObjectInputStream in)	Deserializes the collection in using a custom routine.
E	remove()
boolean	remove(Object object)
boolean	removeAll(Collection<?> coll)
boolean	removeIf(Predicate<? super E> filter)
boolean	retainAll(Collection<?> coll)
static <E> Queue<E>	unmodifiableQueue(Queue<? extends E> queue)	Factory method to create an unmodifiable queue.
private void	writeObject(ObjectOutputStream out)	Serializes this object to an ObjectOutputStream.

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

Field Details

serialVersionUID

private static final long serialVersionUID

Serialization version

See Also:

• Constant Field Values

Constructor Details

UnmodifiableQueue

private UnmodifiableQueue(Queue<? extends E> queue)

Constructor that wraps (not copies).

Parameters:

queue - the queue to decorate, must not be null

Throws:

NullPointerException - if queue is null

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)

Specified by:

add in interface Collection<E>

Specified by:

add in interface Queue<E>

Overrides:

add in class AbstractCollectionDecorator<E>

addAll

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

Specified by:

addAll in interface Collection<E>

Overrides:

addAll in class AbstractCollectionDecorator<E>

clear

public void clear()

Specified by:

clear in interface Collection<E>

Overrides:

clear in class AbstractCollectionDecorator<E>

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)

Specified by:

offer in interface Queue<E>

Overrides:

offer in class AbstractQueueDecorator<E>

poll

public E poll()

Specified by:

poll in interface Queue<E>

Overrides:

poll in class AbstractQueueDecorator<E>

readObject

private void readObject(ObjectInputStream in)
                 throws IOException,
ClassNotFoundException

Deserializes the collection in using a custom routine.

Parameters:

in - the input stream

Throws:

IOException - if an I/O error occurs while reading from the input stream

ClassNotFoundException - if the class of a serialized object cannot be found

remove

public E remove()

Specified by:

remove in interface Queue<E>

Overrides:

remove in class AbstractQueueDecorator<E>

remove

public boolean remove(Object object)

Specified by:

remove in interface Collection<E>

Overrides:

remove in class AbstractCollectionDecorator<E>

removeAll

public boolean removeAll(Collection<?> coll)

Specified by:

removeAll in interface Collection<E>

Overrides:

removeAll in class AbstractCollectionDecorator<E>

removeIf

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

Specified by:

removeIf in interface Collection<E>

Overrides:

removeIf in class AbstractCollectionDecorator<E>

Since:

4.4

retainAll

public boolean retainAll(Collection<?> coll)

Specified by:

retainAll in interface Collection<E>

Overrides:

retainAll in class AbstractCollectionDecorator<E>

writeObject

private void writeObject(ObjectOutputStream out)
                  throws IOException

Serializes this object to an ObjectOutputStream.

Parameters:

out - the target ObjectOutputStream.

Throws:

IOException - thrown when an I/O errors occur writing to the target stream.