程序包 java.util

类 AbstractQueue<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractQueue<E>

类型参数:

E - the type of elements held in this collection

所有已实现的接口:

Iterable<E>, Collection<E>, Queue<E>

直接已知子类:

ArrayBlockingQueue, ConcurrentLinkedQueue, DelayQueue, LinkedBlockingDeque, LinkedBlockingQueue, LinkedTransferQueue, PriorityBlockingQueue, PriorityQueue, SynchronousQueue

public abstract class AbstractQueue<E>
extends AbstractCollection<E>
implements Queue<E>

This class provides skeletal implementations of some Queue operations. The implementations in this class are appropriate when the base implementation does not allow null elements. Methods add, remove, and element are based on offer, poll, and peek, respectively, but throw exceptions instead of indicating failure via false or null returns.

A Queue implementation that extends this class must minimally define a method Queue#offer which does not permit insertion of null elements, along with methods Queue#peek, Queue#poll, Collection#size, and Collection#iterator. Typically, additional methods will be overridden as well. If these requirements cannot be met, consider instead subclassing AbstractCollection.

This class is a member of the Java Collections Framework.

从以下版本开始:

1.5

构造器概要

构造器

限定符	构造器	说明
protected	AbstractQueue()	Constructor for use by subclasses.

方法概要

限定符和类型	方法	说明
boolean	add(E e)	Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions, returning true upon success and throwing an IllegalStateException if no space is currently available.
boolean	addAll(Collection<? extends E> c)	Adds all of the elements in the specified collection to this queue.
void	clear()	Removes all of the elements from this queue.
E	element()	Retrieves, but does not remove, the head of this queue.
E	remove()	Retrieves and removes the head of this queue.

从类继承的方法 java.util.AbstractCollection

contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray, toString

从接口继承的方法 java.util.Collection

contains, containsAll, equals, hashCode, isEmpty, iterator, parallelStream, remove, removeAll, removeIf, retainAll, size, spliterator, stream, toArray, toArray

从接口继承的方法 java.lang.Iterable

forEach

从类继承的方法 java.lang.Object

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

从接口继承的方法 java.util.Queue

offer, peek, poll

构造器详细资料

AbstractQueue

protected AbstractQueue()

Constructor for use by subclasses.

方法详细资料

add

public boolean add(E e)

Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions, returning true upon success and throwing an IllegalStateException if no space is currently available.

This implementation returns true if offer succeeds, else throws an IllegalStateException.

指定者:

add 在接口中 Collection<E>

指定者:

add 在接口中 Queue<E>

覆盖:

add 在类中 AbstractCollection<E>

参数:

e - the element to add

返回:

true (as specified by Collection#add)

抛出:

IllegalStateException - if the element cannot be added at this time due to capacity restrictions

ClassCastException - if the class of the specified element prevents it from being added to this queue

NullPointerException - if the specified element is null and this queue does not permit null elements

IllegalArgumentException - if some property of this element prevents it from being added to this queue

remove

public E remove()

Retrieves and removes the head of this queue. This method differs from poll only in that it throws an exception if this queue is empty.

This implementation returns the result of poll unless the queue is empty.

指定者:

remove 在接口中 Queue<E>

返回:

the head of this queue

抛出:

NoSuchElementException - if this queue is empty

element

public E element()

Retrieves, but does not remove, the head of this queue. This method differs from peek only in that it throws an exception if this queue is empty.

This implementation returns the result of peek unless the queue is empty.

指定者:

element 在接口中 Queue<E>

返回:

the head of this queue

抛出:

NoSuchElementException - if this queue is empty

clear

public void clear()

Removes all of the elements from this queue. The queue will be empty after this call returns.

This implementation repeatedly invokes poll until it returns null.

指定者:

clear 在接口中 Collection<E>

覆盖:

clear 在类中 AbstractCollection<E>

addAll

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

Adds all of the elements in the specified collection to this queue. Attempts to addAll of a queue to itself result in IllegalArgumentException. Further, the behavior of this operation is undefined if the specified collection is modified while the operation is in progress.

This implementation iterates over the specified collection, and adds each element returned by the iterator to this queue, in turn. A runtime exception encountered while trying to add an element (including, in particular, a null element) may result in only some of the elements having been successfully added when the associated exception is thrown.

指定者:

addAll 在接口中 Collection<E>

覆盖:

addAll 在类中 AbstractCollection<E>

参数:

c - collection containing elements to be added to this queue

返回:

true if this queue changed as a result of the call

抛出:

ClassCastException - if the class of an element of the specified collection prevents it from being added to this queue

NullPointerException - if the specified collection contains a null element and this queue does not permit null elements, or if the specified collection is null

IllegalArgumentException - if some property of an element of the specified collection prevents it from being added to this queue, or if the specified collection is this queue

IllegalStateException - if not all the elements can be added at this time due to insertion restrictions

另请参阅:

add(Object)