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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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*/ |
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|
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package java.util.concurrent; |
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import java.util.*; |
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|
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/** |
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* A {@link Deque} that additionally supports operations that wait for |
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* the deque to become non-empty when retrieving an element, and wait |
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* for space to become available in the deque when storing an |
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* element. These methods are summarized in the following table:<p> |
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* |
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* <table BORDER CELLPADDING=3 CELLSPACING=1> |
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* <tr> |
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* <td></td> |
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* <td ALIGN=CENTER COLSPAN = 2> <b>First Element (Head)</b></td> |
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* <td ALIGN=CENTER COLSPAN = 2> <b>Last Element (Tail)</b></td> |
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* </tr> |
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* <tr> |
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* <td></td> |
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* <td ALIGN=CENTER><em>Block</em></td> |
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* <td ALIGN=CENTER><em>Time out</em></td> |
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* <td ALIGN=CENTER><em>Block</em></td> |
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* <td ALIGN=CENTER><em>Time out</em></td> |
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* </tr> |
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* <tr> |
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* <td><b>Insert</b></td> |
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* <td>{@link #putFirst putFirst(e)}</td> |
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* <td>{@link #offerFirst(Object, long, TimeUnit) offerFirst(e, time, unit)}</td> |
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* <td>{@link #putLast putLast(e)}</td> |
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* <td>{@link #offerLast(Object, long, TimeUnit) offerLast(e, time, unit)}</td> |
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* </tr> |
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* <tr> |
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* <td><b>Remove</b></td> |
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* <td>{@link #takeFirst takeFirst()}</td> |
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* <td>{@link #pollFirst(long, TimeUnit) pollFirst(time, unit)}</td> |
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* <td>{@link #takeLast takeLast()}</td> |
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* <td>{@link #pollLast(long, TimeUnit) pollLast(time, unit)}</td> |
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* </tr> |
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* </table> |
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* |
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* <p>Like any {@link BlockingQueue}, a <tt>BlockingDeque</tt> is |
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* thread safe and may (or may not) be capacity-constrained. A |
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* <tt>BlockingDeque</tt> implementation may be used directly as a |
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* FIFO <tt>BlockingQueue</tt>. The blocking methods inherited from |
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* the <tt>BlockingQueue</tt> interface are precisely equivalent to |
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* <tt>BlockingDeque</tt> methods as indicated in the following table:<p> |
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* |
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* <table BORDER CELLPADDING=3 CELLSPACING=1> |
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* <tr> |
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* <td ALIGN=CENTER> <b><tt>BlockingQueue</tt> Method</b></td> |
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* <td ALIGN=CENTER> <b>Equivalent <tt>BlockingDeque</tt> Method</b></td> |
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* </tr> |
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* <tr> |
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* <tr> |
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* <td>{@link java.util.concurrent.BlockingQueue#put put(e)}</td> |
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* <td>{@link #putLast putLast(e)}</td> |
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* </tr> |
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* <tr> |
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* <td>{@link java.util.concurrent.BlockingQueue#take take()}</td> |
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* <td>{@link #takeFirst takeFirst()}</td> |
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* </tr> |
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* <tr> |
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* <td>{@link java.util.concurrent.BlockingQueue#offer(Object, long, TimeUnit) offer(e, time. unit)}</td> |
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* <td>{@link #offerLast(Object, long, TimeUnit) offerLast(e, time, unit)}</td> |
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* </tr> |
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* <tr> |
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* <td>{@link java.util.concurrent.BlockingQueue#poll(long, TimeUnit) poll(time, unit)}</td> |
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* <td>{@link #pollFirst(long, TimeUnit) pollFirst(time, unit)}</td> |
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* </tr> |
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* </table> |
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* |
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* |
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* <p>This interface is a member of the |
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* <a href="{@docRoot}/../guide/collections/index.html"> |
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* Java Collections Framework</a>. |
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* |
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* @since 1.6 |
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* @author Doug Lea |
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* @param <E> the type of elements held in this collection |
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*/ |
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public interface BlockingDeque<E> extends Deque<E>, BlockingQueue<E> { |
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|
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/** |
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* Adds the specified element as the first element of this deque, |
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* waiting if necessary for space to become available. |
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* @param o the element to add |
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* @throws InterruptedException if interrupted while waiting. |
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* @throws NullPointerException if the specified element is <tt>null</tt>. |
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*/ |
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void putFirst(E o) throws InterruptedException; |
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|
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/** |
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* Adds the specified element as the last element of this deque, |
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* waiting if necessary for space to become available. |
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* @param o the element to add |
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* @throws InterruptedException if interrupted while waiting. |
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* @throws NullPointerException if the specified element is <tt>null</tt>. |
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*/ |
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void putLast(E o) throws InterruptedException; |
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|
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/** |
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* Retrieves and removes the first element of this deque, waiting |
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* if no elements are present on this deque. |
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* @return the head of this deque |
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* @throws InterruptedException if interrupted while waiting. |
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*/ |
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E takeFirst() throws InterruptedException; |
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|
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/** |
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* Retrieves and removes the last element of this deque, waiting |
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* if no elements are present on this deque. |
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* @return the head of this deque |
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* @throws InterruptedException if interrupted while waiting. |
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*/ |
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E takeLast() throws InterruptedException; |
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|
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/** |
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* Inserts the specified element as the first element of this deque, |
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* waiting if necessary up to the specified wait time for space to |
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* become available. |
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* @param o the element to add |
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* @param timeout how long to wait before giving up, in units of |
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* <tt>unit</tt> |
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* @param unit a <tt>TimeUnit</tt> determining how to interpret the |
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* <tt>timeout</tt> parameter |
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* @return <tt>true</tt> if successful, or <tt>false</tt> if |
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* the specified waiting time elapses before space is available. |
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* @throws InterruptedException if interrupted while waiting. |
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* @throws NullPointerException if the specified element is <tt>null</tt>. |
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*/ |
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boolean offerFirst(E o, long timeout, TimeUnit unit) |
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throws InterruptedException; |
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|
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/** |
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* Inserts the specified element as the last element of this deque, |
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* waiting if necessary up to the specified wait time for space to |
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* become available. |
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* @param o the element to add |
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* @param timeout how long to wait before giving up, in units of |
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* <tt>unit</tt> |
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* @param unit a <tt>TimeUnit</tt> determining how to interpret the |
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* <tt>timeout</tt> parameter |
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* @return <tt>true</tt> if successful, or <tt>false</tt> if |
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* the specified waiting time elapses before space is available. |
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* @throws InterruptedException if interrupted while waiting. |
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* @throws NullPointerException if the specified element is <tt>null</tt>. |
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*/ |
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boolean offerLast(E o, long timeout, TimeUnit unit) |
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throws InterruptedException; |
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|
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|
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/** |
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* Retrieves and removes the first element of this deque, waiting |
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* if necessary up to the specified wait time if no elements are |
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* present on this deque. |
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* @param timeout how long to wait before giving up, in units of |
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* <tt>unit</tt> |
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* @param unit a <tt>TimeUnit</tt> determining how to interpret the |
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* <tt>timeout</tt> parameter |
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* @return the head of this deque, or <tt>null</tt> if the |
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* specified waiting time elapses before an element is present. |
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* @throws InterruptedException if interrupted while waiting. |
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*/ |
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E pollFirst(long timeout, TimeUnit unit) |
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throws InterruptedException; |
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|
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/** |
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* Retrieves and removes the last element of this deque, waiting |
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* if necessary up to the specified wait time if no elements are |
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* present on this deque. |
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* @param timeout how long to wait before giving up, in units of |
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* <tt>unit</tt> |
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* @param unit a <tt>TimeUnit</tt> determining how to interpret the |
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* <tt>timeout</tt> parameter |
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* @return the head of this deque, or <tt>null</tt> if the |
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* specified waiting time elapses before an element is present. |
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* @throws InterruptedException if interrupted while waiting. |
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*/ |
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E pollLast(long timeout, TimeUnit unit) |
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throws InterruptedException; |
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|
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/** |
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* Adds the specified element as the last element of this deque, |
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* waiting if necessary for space to become available. |
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* |
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* <p>This method is equivalent to {@link #putLast}. |
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* |
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* @param o the element to add |
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* @throws InterruptedException if interrupted while waiting. |
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* @throws NullPointerException if the specified element is <tt>null</tt>. |
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*/ |
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void put(E o) throws InterruptedException; |
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|
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/** |
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* Inserts the specified element as the last element of this |
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* deque, if possible. When using deques that may impose |
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* insertion restrictions (for example capacity bounds), method |
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* <tt>offer</tt> is generally preferable to method {@link |
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* Collection#add}, which can fail to insert an element only by |
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* throwing an exception. |
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* |
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* <p>This method is equivalent to {@link #offerLast}. |
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* |
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* @param o the element to add. |
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* @return <tt>true</tt> if it was possible to add the element to |
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* this deque, else <tt>false</tt> |
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* @throws NullPointerException if the specified element is <tt>null</tt> |
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*/ |
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boolean offer(E o, long timeout, TimeUnit unit) |
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throws InterruptedException; |
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|
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/** |
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* Retrieves and removes the first element of this deque, waiting |
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* if no elements are present on this deque. |
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* |
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* <p>This method is equivalent to {@link #takeFirst}. |
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* |
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* @return the head of this deque |
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* @throws InterruptedException if interrupted while waiting. |
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*/ |
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E take() throws InterruptedException; |
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|
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/** |
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* Retrieves and removes the first element of this deque, waiting |
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* if necessary up to the specified wait time if no elements are |
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* present on this deque. |
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* |
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* <p>This method is equivalent to {@link #pollFirst}. |
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* |
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* @param timeout how long to wait before giving up, in units of |
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* <tt>unit</tt> |
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* @param unit a <tt>TimeUnit</tt> determining how to interpret the |
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* <tt>timeout</tt> parameter |
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* @return the head of this deque, or <tt>null</tt> if the |
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* specified waiting time elapses before an element is present. |
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* @throws InterruptedException if interrupted while waiting. |
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*/ |
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E poll(long timeout, TimeUnit unit) |
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throws InterruptedException; |
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} |
