基本上Queue的定义只能对 头remove, 尾添加, 制定某个元素似乎不支持。/* * @(#)BlockingQueue.java 1.8 04/07/12 * * Copyright 2004 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */package java.util.concurrent;import java.util.Collection; import java.util.Queue; public interface BlockingQueue<E> extends Queue<E> { /** * Inserts the specified element into this queue, if possible. When * using queues that may impose insertion restrictions (for * example capacity bounds), method <tt>offer</tt> is generally * preferable to method {@link Collection#add}, which can fail to * insert an element only by throwing an exception. * * @param o the element to add. * @return <tt>true</tt> if it was possible to add the element to * this queue, else <tt>false</tt> * @throws NullPointerException if the specified element is <tt>null</tt> */ boolean offer(E o);
/** * Inserts the specified element into this queue, waiting if necessary * up to the specified wait time for space to become available. * @param o the element to add * @param timeout how long to wait before giving up, in units of * <tt>unit</tt> * @param unit a <tt>TimeUnit</tt> determining how to interpret the * <tt>timeout</tt> parameter * @return <tt>true</tt> if successful, or <tt>false</tt> if * the specified waiting time elapses before space is available. * @throws InterruptedException if interrupted while waiting. * @throws NullPointerException if the specified element is <tt>null</tt>. */ boolean offer(E o, long timeout, TimeUnit unit) throws InterruptedException; /** * Retrieves and removes the head of this queue, waiting * if necessary up to the specified wait time if no elements are * present on this queue. * @param timeout how long to wait before giving up, in units of * <tt>unit</tt> * @param unit a <tt>TimeUnit</tt> determining how to interpret the * <tt>timeout</tt> parameter * @return the head of this queue, or <tt>null</tt> if the * specified waiting time elapses before an element is present. * @throws InterruptedException if interrupted while waiting. */ E poll(long timeout, TimeUnit unit) throws InterruptedException; /** * Retrieves and removes the head of this queue, waiting * if no elements are present on this queue. * @return the head of this queue * @throws InterruptedException if interrupted while waiting. */ E take() throws InterruptedException; /** * Adds the specified element to this queue, waiting if necessary for * space to become available. * @param o the element to add * @throws InterruptedException if interrupted while waiting. * @throws NullPointerException if the specified element is <tt>null</tt>. */ void put(E o) throws InterruptedException; /** * Returns the number of elements that this queue can ideally (in * the absence of memory or resource constraints) accept without * blocking, or <tt>Integer.MAX_VALUE</tt> if there is no * intrinsic limit. * <p>Note that you <em>cannot</em> always tell if * an attempt to <tt>add</tt> an element will succeed by * inspecting <tt>remainingCapacity</tt> because it may be the * case that another thread is about to <tt>put</tt> or <tt>take</tt> an * element. * @return the remaining capacity */ int remainingCapacity(); /** * Adds the specified element to this queue if it is possible to * do so immediately, returning <tt>true</tt> upon success, else * throwing an IllegalStateException. * @param o the element * @return <tt>true</tt> (as per the general contract of * <tt>Collection.add</tt>). * * @throws NullPointerException if the specified element is <tt>null</tt> * @throws IllegalStateException if element cannot be added */ boolean add(E o); /** * Removes all available elements from this queue and adds them * into the given collection. This operation may be more * efficient than repeatedly polling this queue. A failure * encountered while attempting to <tt>add</tt> elements to * collection <tt>c</tt> may result in elements being in neither, * either or both collections when the associated exception is * thrown. Attempts to drain a queue to itself result in * <tt>IllegalArgumentException</tt>. Further, the behavior of * this operation is undefined if the specified collection is * modified while the operation is in progress. * * @param c the collection to transfer elements into * @return the number of elements transferred. * @throws NullPointerException if c is null * @throws IllegalArgumentException if c is this queue * */ int drainTo(Collection<? super E> c);
/** * Removes at most the given number of available elements from * this queue and adds them into the given collection. A failure * encountered while attempting to <tt>add</tt> elements to * collection <tt>c</tt> may result in elements being in neither, * either or both collections when the associated exception is * thrown. Attempts to drain a queue to itself result in * <tt>IllegalArgumentException</tt>. Further, the behavior of * this operation is undefined if the specified collection is * modified while the operation is in progress. * * @param c the collection to transfer elements into * @param maxElements the maximum number of elements to transfer * @return the number of elements transferred. * @throws NullPointerException if c is null * @throws IllegalArgumentException if c is this queue */ int drainTo(Collection<? super E> c, int maxElements); } ========================================== /* * @(#)Queue.java 1.5 03/12/19 * * Copyright 2004 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */package java.util; public interface Queue<E> extends Collection<E> { /** * Inserts the specified element into this queue, if possible. When * using queues that may impose insertion restrictions (for * example capacity bounds), method <tt>offer</tt> is generally * preferable to method {@link Collection#add}, which can fail to * insert an element only by throwing an exception. * * @param o the element to insert. * @return <tt>true</tt> if it was possible to add the element to * this queue, else <tt>false</tt> */ boolean offer(E o); /** * Retrieves and removes the head of this queue, or <tt>null</tt> * if this queue is empty. * * @return the head of this queue, or <tt>null</tt> if this * queue is empty. */ E poll(); /** * Retrieves and removes the head of this queue. This method * differs from the <tt>poll</tt> method in that it throws an * exception if this queue is empty. * * @return the head of this queue. * @throws NoSuchElementException if this queue is empty. */ E remove(); /** * Retrieves, but does not remove, the head of this queue, * returning <tt>null</tt> if this queue is empty. * * @return the head of this queue, or <tt>null</tt> if this queue * is empty. */ E peek(); /** * Retrieves, but does not remove, the head of this queue. This method * differs from the <tt>peek</tt> method only in that it throws an * exception if this queue is empty. * * @return the head of this queue. * @throws NoSuchElementException if this queue is empty. */ E element(); }
* @(#)BlockingQueue.java 1.8 04/07/12
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/package java.util.concurrent;import java.util.Collection;
import java.util.Queue;
public interface BlockingQueue<E> extends Queue<E> { /**
* Inserts the specified element into this queue, if possible. When
* using queues that may impose insertion restrictions (for
* example capacity bounds), method <tt>offer</tt> is generally
* preferable to method {@link Collection#add}, which can fail to
* insert an element only by throwing an exception.
*
* @param o the element to add.
* @return <tt>true</tt> if it was possible to add the element to
* this queue, else <tt>false</tt>
* @throws NullPointerException if the specified element is <tt>null</tt>
*/
boolean offer(E o);
/**
* Inserts the specified element into this queue, waiting if necessary
* up to the specified wait time for space to become available.
* @param o the element to add
* @param timeout how long to wait before giving up, in units of
* <tt>unit</tt>
* @param unit a <tt>TimeUnit</tt> determining how to interpret the
* <tt>timeout</tt> parameter
* @return <tt>true</tt> if successful, or <tt>false</tt> if
* the specified waiting time elapses before space is available.
* @throws InterruptedException if interrupted while waiting.
* @throws NullPointerException if the specified element is <tt>null</tt>.
*/
boolean offer(E o, long timeout, TimeUnit unit)
throws InterruptedException; /**
* Retrieves and removes the head of this queue, waiting
* if necessary up to the specified wait time if no elements are
* present on this queue.
* @param timeout how long to wait before giving up, in units of
* <tt>unit</tt>
* @param unit a <tt>TimeUnit</tt> determining how to interpret the
* <tt>timeout</tt> parameter
* @return the head of this queue, or <tt>null</tt> if the
* specified waiting time elapses before an element is present.
* @throws InterruptedException if interrupted while waiting.
*/
E poll(long timeout, TimeUnit unit)
throws InterruptedException; /**
* Retrieves and removes the head of this queue, waiting
* if no elements are present on this queue.
* @return the head of this queue
* @throws InterruptedException if interrupted while waiting.
*/
E take() throws InterruptedException; /**
* Adds the specified element to this queue, waiting if necessary for
* space to become available.
* @param o the element to add
* @throws InterruptedException if interrupted while waiting.
* @throws NullPointerException if the specified element is <tt>null</tt>.
*/
void put(E o) throws InterruptedException; /**
* Returns the number of elements that this queue can ideally (in
* the absence of memory or resource constraints) accept without
* blocking, or <tt>Integer.MAX_VALUE</tt> if there is no
* intrinsic limit.
* <p>Note that you <em>cannot</em> always tell if
* an attempt to <tt>add</tt> an element will succeed by
* inspecting <tt>remainingCapacity</tt> because it may be the
* case that another thread is about to <tt>put</tt> or <tt>take</tt> an
* element.
* @return the remaining capacity
*/
int remainingCapacity(); /**
* Adds the specified element to this queue if it is possible to
* do so immediately, returning <tt>true</tt> upon success, else
* throwing an IllegalStateException.
* @param o the element
* @return <tt>true</tt> (as per the general contract of
* <tt>Collection.add</tt>).
*
* @throws NullPointerException if the specified element is <tt>null</tt>
* @throws IllegalStateException if element cannot be added
*/
boolean add(E o); /**
* Removes all available elements from this queue and adds them
* into the given collection. This operation may be more
* efficient than repeatedly polling this queue. A failure
* encountered while attempting to <tt>add</tt> elements to
* collection <tt>c</tt> may result in elements being in neither,
* either or both collections when the associated exception is
* thrown. Attempts to drain a queue to itself result in
* <tt>IllegalArgumentException</tt>. Further, the behavior of
* this operation is undefined if the specified collection is
* modified while the operation is in progress.
*
* @param c the collection to transfer elements into
* @return the number of elements transferred.
* @throws NullPointerException if c is null
* @throws IllegalArgumentException if c is this queue
*
*/
int drainTo(Collection<? super E> c);
/**
* Removes at most the given number of available elements from
* this queue and adds them into the given collection. A failure
* encountered while attempting to <tt>add</tt> elements to
* collection <tt>c</tt> may result in elements being in neither,
* either or both collections when the associated exception is
* thrown. Attempts to drain a queue to itself result in
* <tt>IllegalArgumentException</tt>. Further, the behavior of
* this operation is undefined if the specified collection is
* modified while the operation is in progress.
*
* @param c the collection to transfer elements into
* @param maxElements the maximum number of elements to transfer
* @return the number of elements transferred.
* @throws NullPointerException if c is null
* @throws IllegalArgumentException if c is this queue
*/
int drainTo(Collection<? super E> c, int maxElements);
}
==========================================
/*
* @(#)Queue.java 1.5 03/12/19
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/package java.util;
public interface Queue<E> extends Collection<E> { /**
* Inserts the specified element into this queue, if possible. When
* using queues that may impose insertion restrictions (for
* example capacity bounds), method <tt>offer</tt> is generally
* preferable to method {@link Collection#add}, which can fail to
* insert an element only by throwing an exception.
*
* @param o the element to insert.
* @return <tt>true</tt> if it was possible to add the element to
* this queue, else <tt>false</tt>
*/
boolean offer(E o); /**
* Retrieves and removes the head of this queue, or <tt>null</tt>
* if this queue is empty.
*
* @return the head of this queue, or <tt>null</tt> if this
* queue is empty.
*/
E poll(); /**
* Retrieves and removes the head of this queue. This method
* differs from the <tt>poll</tt> method in that it throws an
* exception if this queue is empty.
*
* @return the head of this queue.
* @throws NoSuchElementException if this queue is empty.
*/
E remove(); /**
* Retrieves, but does not remove, the head of this queue,
* returning <tt>null</tt> if this queue is empty.
*
* @return the head of this queue, or <tt>null</tt> if this queue
* is empty.
*/
E peek(); /**
* Retrieves, but does not remove, the head of this queue. This method
* differs from the <tt>peek</tt> method only in that it throws an
* exception if this queue is empty.
*
* @return the head of this queue.
* @throws NoSuchElementException if this queue is empty.
*/
E element();
}
当然移动中间元素也能做到,用Iterator
我写了个例子, 把元素2移到第3个位置.
LinkedBlockingDeque<String> deque = new LinkedBlockingDeque<String>();
deque.add("1");
deque.add("2");
deque.add("3");
deque.add("4");
String[] strs = deque.toArray(new String[0]);
strs[2] = "2";
deque = new LinkedBlockingDeque<String>(Arrays.asList(strs));
System.err.println(deque);