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jeremybenn |
/*
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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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package java.util.concurrent;
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import java.util.*;
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/**
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* A {@link Deque} that additionally supports blocking operations that wait
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* for the deque to become non-empty when retrieving an element, and wait for
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* space to become available in the deque when storing an element.
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*
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* <p><tt>BlockingDeque</tt> methods come in four forms, with different ways
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* of handling operations that cannot be satisfied immediately, but may be
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* satisfied at some point in the future:
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* one throws an exception, the second returns a special value (either
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* <tt>null</tt> or <tt>false</tt>, depending on the operation), the third
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* blocks the current thread indefinitely until the operation can succeed,
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* and the fourth blocks for only a given maximum time limit before giving
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* up. These methods are summarized in the following table:
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*
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* <p>
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* <table BORDER CELLPADDING=3 CELLSPACING=1>
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* <tr>
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* <td ALIGN=CENTER COLSPAN = 5> <b>First Element (Head)</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>Throws exception</em></td>
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* <td ALIGN=CENTER><em>Special value</em></td>
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* <td ALIGN=CENTER><em>Blocks</em></td>
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* <td ALIGN=CENTER><em>Times 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 #addFirst addFirst(e)}</td>
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* <td>{@link #offerFirst(Object) offerFirst(e)}</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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* </tr>
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* <tr>
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* <td><b>Remove</b></td>
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* <td>{@link #removeFirst removeFirst()}</td>
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* <td>{@link #pollFirst pollFirst()}</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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* </tr>
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* <tr>
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* <td><b>Examine</b></td>
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* <td>{@link #getFirst getFirst()}</td>
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* <td>{@link #peekFirst peekFirst()}</td>
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* <td><em>not applicable</em></td>
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* <td><em>not applicable</em></td>
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* </tr>
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* <tr>
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* <td ALIGN=CENTER COLSPAN = 5> <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>Throws exception</em></td>
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* <td ALIGN=CENTER><em>Special value</em></td>
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* <td ALIGN=CENTER><em>Blocks</em></td>
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* <td ALIGN=CENTER><em>Times 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 #addLast addLast(e)}</td>
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* <td>{@link #offerLast(Object) offerLast(e)}</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 #removeLast() removeLast()}</td>
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* <td>{@link #pollLast() pollLast()}</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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* <tr>
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* <td><b>Examine</b></td>
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* <td>{@link #getLast getLast()}</td>
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* <td>{@link #peekLast peekLast()}</td>
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* <td><em>not applicable</em></td>
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* <td><em>not applicable</em></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 thread safe,
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* does not permit null elements, and may (or may not) be
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* capacity-constrained.
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*
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* <p>A <tt>BlockingDeque</tt> implementation may be used directly as a FIFO
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* <tt>BlockingQueue</tt>. The methods inherited from the
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* <tt>BlockingQueue</tt> interface are precisely equivalent to
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* <tt>BlockingDeque</tt> methods as indicated in the following table:
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*
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* <p>
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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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* <td ALIGN=CENTER COLSPAN = 2> <b>Insert</b></td>
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* </tr>
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* <tr>
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* <td>{@link #add(Object) add(e)}</td>
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* <td>{@link #addLast(Object) addLast(e)}</td>
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* </tr>
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* <tr>
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* <td>{@link #offer(Object) offer(e)}</td>
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* <td>{@link #offerLast(Object) offerLast(e)}</td>
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* </tr>
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* <tr>
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* <td>{@link #put(Object) put(e)}</td>
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* <td>{@link #putLast(Object) putLast(e)}</td>
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* </tr>
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* <tr>
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* <td>{@link #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 ALIGN=CENTER COLSPAN = 2> <b>Remove</b></td>
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* </tr>
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* <tr>
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* <td>{@link #remove() remove()}</td>
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* <td>{@link #removeFirst() removeFirst()}</td>
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* </tr>
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* <tr>
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* <td>{@link #poll() poll()}</td>
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* <td>{@link #pollFirst() pollFirst()}</td>
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* </tr>
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* <tr>
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* <td>{@link #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 #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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* <tr>
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* <td ALIGN=CENTER COLSPAN = 2> <b>Examine</b></td>
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* </tr>
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* <tr>
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* <td>{@link #element() element()}</td>
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* <td>{@link #getFirst() getFirst()}</td>
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* </tr>
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* <tr>
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* <td>{@link #peek() peek()}</td>
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* <td>{@link #peekFirst() peekFirst()}</td>
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* </tr>
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* </table>
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*
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* <p>Memory consistency effects: As with other concurrent
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* collections, actions in a thread prior to placing an object into a
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* {@code BlockingDeque}
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* <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
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* actions subsequent to the access or removal of that element from
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* the {@code BlockingDeque} in another thread.
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*
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* <p>This interface is a member of the
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* <a href="{@docRoot}/../technotes/guides/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 BlockingQueue<E>, Deque<E> {
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/*
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* We have "diamond" multiple interface inheritance here, and that
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* introduces ambiguities. Methods might end up with different
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* specs depending on the branch chosen by javadoc. Thus a lot of
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* methods specs here are copied from superinterfaces.
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*/
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/**
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* Inserts the specified element at the front of this deque if it is
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* possible to do so immediately without violating capacity restrictions,
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* throwing an <tt>IllegalStateException</tt> if no space is currently
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* available. When using a capacity-restricted deque, it is generally
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* preferable to use {@link #offerFirst(Object) offerFirst}.
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*
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* @param e the element to add
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* @throws IllegalStateException {@inheritDoc}
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException {@inheritDoc}
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*/
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void addFirst(E e);
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/**
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* Inserts the specified element at the end of this deque if it is
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* possible to do so immediately without violating capacity restrictions,
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* throwing an <tt>IllegalStateException</tt> if no space is currently
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* available. When using a capacity-restricted deque, it is generally
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* preferable to use {@link #offerLast(Object) offerLast}.
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*
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* @param e the element to add
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* @throws IllegalStateException {@inheritDoc}
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException {@inheritDoc}
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*/
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void addLast(E e);
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/**
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* Inserts the specified element at the front of this deque if it is
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* possible to do so immediately without violating capacity restrictions,
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* returning <tt>true</tt> upon success and <tt>false</tt> if no space is
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* currently available.
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* When using a capacity-restricted deque, this method is generally
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* preferable to the {@link #addFirst(Object) addFirst} method, which can
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* fail to insert an element only by throwing an exception.
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*
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* @param e the element to add
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException {@inheritDoc}
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*/
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boolean offerFirst(E e);
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/**
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* Inserts the specified element at the end of this deque if it is
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* possible to do so immediately without violating capacity restrictions,
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* returning <tt>true</tt> upon success and <tt>false</tt> if no space is
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* currently available.
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* When using a capacity-restricted deque, this method is generally
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* preferable to the {@link #addLast(Object) addLast} method, which can
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* fail to insert an element only by throwing an exception.
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*
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* @param e the element to add
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException {@inheritDoc}
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*/
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boolean offerLast(E e);
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/**
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* Inserts the specified element at the front of this deque,
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* waiting if necessary for space to become available.
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*
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* @param e the element to add
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* @throws InterruptedException if interrupted while waiting
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* @throws ClassCastException if the class of the specified element
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* prevents it from being added to this deque
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException if some property of the specified
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* element prevents it from being added to this deque
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*/
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void putFirst(E e) throws InterruptedException;
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/**
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* Inserts the specified element at the end of this deque,
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* waiting if necessary for space to become available.
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*
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* @param e the element to add
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* @throws InterruptedException if interrupted while waiting
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* @throws ClassCastException if the class of the specified element
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* prevents it from being added to this deque
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException if some property of the specified
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* element prevents it from being added to this deque
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*/
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void putLast(E e) throws InterruptedException;
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/**
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* Inserts the specified element at the front of this deque,
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* waiting up to the specified wait time if necessary for space to
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* become available.
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*
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* @param e 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 ClassCastException if the class of the specified element
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* prevents it from being added to this deque
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException if some property of the specified
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* element prevents it from being added to this deque
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*/
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boolean offerFirst(E e, long timeout, TimeUnit unit)
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throws InterruptedException;
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/**
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* Inserts the specified element at the end of this deque,
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* waiting up to the specified wait time if necessary for space to
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* become available.
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*
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* @param e 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 ClassCastException if the class of the specified element
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* prevents it from being added to this deque
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* @throws NullPointerException if the specified element is null
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* @throws IllegalArgumentException if some property of the specified
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* element prevents it from being added to this deque
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*/
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boolean offerLast(E e, long timeout, TimeUnit unit)
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throws InterruptedException;
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/**
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* Retrieves and removes the first element of this deque, waiting
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* if necessary until an element becomes available.
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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 takeFirst() throws InterruptedException;
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/**
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* Retrieves and removes the last element of this deque, waiting
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* if necessary until an element becomes available.
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*
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|
|
* @return the tail of this deque
|
327 |
|
|
* @throws InterruptedException if interrupted while waiting
|
328 |
|
|
*/
|
329 |
|
|
E takeLast() throws InterruptedException;
|
330 |
|
|
|
331 |
|
|
/**
|
332 |
|
|
* Retrieves and removes the first element of this deque, waiting
|
333 |
|
|
* up to the specified wait time if necessary for an element to
|
334 |
|
|
* become available.
|
335 |
|
|
*
|
336 |
|
|
* @param timeout how long to wait before giving up, in units of
|
337 |
|
|
* <tt>unit</tt>
|
338 |
|
|
* @param unit a <tt>TimeUnit</tt> determining how to interpret the
|
339 |
|
|
* <tt>timeout</tt> parameter
|
340 |
|
|
* @return the head of this deque, or <tt>null</tt> if the specified
|
341 |
|
|
* waiting time elapses before an element is available
|
342 |
|
|
* @throws InterruptedException if interrupted while waiting
|
343 |
|
|
*/
|
344 |
|
|
E pollFirst(long timeout, TimeUnit unit)
|
345 |
|
|
throws InterruptedException;
|
346 |
|
|
|
347 |
|
|
/**
|
348 |
|
|
* Retrieves and removes the last element of this deque, waiting
|
349 |
|
|
* up to the specified wait time if necessary for an element to
|
350 |
|
|
* become available.
|
351 |
|
|
*
|
352 |
|
|
* @param timeout how long to wait before giving up, in units of
|
353 |
|
|
* <tt>unit</tt>
|
354 |
|
|
* @param unit a <tt>TimeUnit</tt> determining how to interpret the
|
355 |
|
|
* <tt>timeout</tt> parameter
|
356 |
|
|
* @return the tail of this deque, or <tt>null</tt> if the specified
|
357 |
|
|
* waiting time elapses before an element is available
|
358 |
|
|
* @throws InterruptedException if interrupted while waiting
|
359 |
|
|
*/
|
360 |
|
|
E pollLast(long timeout, TimeUnit unit)
|
361 |
|
|
throws InterruptedException;
|
362 |
|
|
|
363 |
|
|
/**
|
364 |
|
|
* Removes the first occurrence of the specified element from this deque.
|
365 |
|
|
* If the deque does not contain the element, it is unchanged.
|
366 |
|
|
* More formally, removes the first element <tt>e</tt> such that
|
367 |
|
|
* <tt>o.equals(e)</tt> (if such an element exists).
|
368 |
|
|
* Returns <tt>true</tt> if this deque contained the specified element
|
369 |
|
|
* (or equivalently, if this deque changed as a result of the call).
|
370 |
|
|
*
|
371 |
|
|
* @param o element to be removed from this deque, if present
|
372 |
|
|
* @return <tt>true</tt> if an element was removed as a result of this call
|
373 |
|
|
* @throws ClassCastException if the class of the specified element
|
374 |
|
|
* is incompatible with this deque (optional)
|
375 |
|
|
* @throws NullPointerException if the specified element is null (optional)
|
376 |
|
|
*/
|
377 |
|
|
boolean removeFirstOccurrence(Object o);
|
378 |
|
|
|
379 |
|
|
/**
|
380 |
|
|
* Removes the last occurrence of the specified element from this deque.
|
381 |
|
|
* If the deque does not contain the element, it is unchanged.
|
382 |
|
|
* More formally, removes the last element <tt>e</tt> such that
|
383 |
|
|
* <tt>o.equals(e)</tt> (if such an element exists).
|
384 |
|
|
* Returns <tt>true</tt> if this deque contained the specified element
|
385 |
|
|
* (or equivalently, if this deque changed as a result of the call).
|
386 |
|
|
*
|
387 |
|
|
* @param o element to be removed from this deque, if present
|
388 |
|
|
* @return <tt>true</tt> if an element was removed as a result of this call
|
389 |
|
|
* @throws ClassCastException if the class of the specified element
|
390 |
|
|
* is incompatible with this deque (optional)
|
391 |
|
|
* @throws NullPointerException if the specified element is null (optional)
|
392 |
|
|
*/
|
393 |
|
|
boolean removeLastOccurrence(Object o);
|
394 |
|
|
|
395 |
|
|
// *** BlockingQueue methods ***
|
396 |
|
|
|
397 |
|
|
/**
|
398 |
|
|
* Inserts the specified element into the queue represented by this deque
|
399 |
|
|
* (in other words, at the tail of this deque) if it is possible to do so
|
400 |
|
|
* immediately without violating capacity restrictions, returning
|
401 |
|
|
* <tt>true</tt> upon success and throwing an
|
402 |
|
|
* <tt>IllegalStateException</tt> if no space is currently available.
|
403 |
|
|
* When using a capacity-restricted deque, it is generally preferable to
|
404 |
|
|
* use {@link #offer(Object) offer}.
|
405 |
|
|
*
|
406 |
|
|
* <p>This method is equivalent to {@link #addLast(Object) addLast}.
|
407 |
|
|
*
|
408 |
|
|
* @param e the element to add
|
409 |
|
|
* @throws IllegalStateException {@inheritDoc}
|
410 |
|
|
* @throws ClassCastException if the class of the specified element
|
411 |
|
|
* prevents it from being added to this deque
|
412 |
|
|
* @throws NullPointerException if the specified element is null
|
413 |
|
|
* @throws IllegalArgumentException if some property of the specified
|
414 |
|
|
* element prevents it from being added to this deque
|
415 |
|
|
*/
|
416 |
|
|
boolean add(E e);
|
417 |
|
|
|
418 |
|
|
/**
|
419 |
|
|
* Inserts the specified element into the queue represented by this deque
|
420 |
|
|
* (in other words, at the tail of this deque) if it is possible to do so
|
421 |
|
|
* immediately without violating capacity restrictions, returning
|
422 |
|
|
* <tt>true</tt> upon success and <tt>false</tt> if no space is currently
|
423 |
|
|
* available. When using a capacity-restricted deque, this method is
|
424 |
|
|
* generally preferable to the {@link #add} method, which can fail to
|
425 |
|
|
* insert an element only by throwing an exception.
|
426 |
|
|
*
|
427 |
|
|
* <p>This method is equivalent to {@link #offerLast(Object) offerLast}.
|
428 |
|
|
*
|
429 |
|
|
* @param e the element to add
|
430 |
|
|
* @throws ClassCastException if the class of the specified element
|
431 |
|
|
* prevents it from being added to this deque
|
432 |
|
|
* @throws NullPointerException if the specified element is null
|
433 |
|
|
* @throws IllegalArgumentException if some property of the specified
|
434 |
|
|
* element prevents it from being added to this deque
|
435 |
|
|
*/
|
436 |
|
|
boolean offer(E e);
|
437 |
|
|
|
438 |
|
|
/**
|
439 |
|
|
* Inserts the specified element into the queue represented by this deque
|
440 |
|
|
* (in other words, at the tail of this deque), waiting if necessary for
|
441 |
|
|
* space to become available.
|
442 |
|
|
*
|
443 |
|
|
* <p>This method is equivalent to {@link #putLast(Object) putLast}.
|
444 |
|
|
*
|
445 |
|
|
* @param e the element to add
|
446 |
|
|
* @throws InterruptedException {@inheritDoc}
|
447 |
|
|
* @throws ClassCastException if the class of the specified element
|
448 |
|
|
* prevents it from being added to this deque
|
449 |
|
|
* @throws NullPointerException if the specified element is null
|
450 |
|
|
* @throws IllegalArgumentException if some property of the specified
|
451 |
|
|
* element prevents it from being added to this deque
|
452 |
|
|
*/
|
453 |
|
|
void put(E e) throws InterruptedException;
|
454 |
|
|
|
455 |
|
|
/**
|
456 |
|
|
* Inserts the specified element into the queue represented by this deque
|
457 |
|
|
* (in other words, at the tail of this deque), waiting up to the
|
458 |
|
|
* specified wait time if necessary for space to become available.
|
459 |
|
|
*
|
460 |
|
|
* <p>This method is equivalent to
|
461 |
|
|
* {@link #offerLast(Object,long,TimeUnit) offerLast}.
|
462 |
|
|
*
|
463 |
|
|
* @param e the element to add
|
464 |
|
|
* @return <tt>true</tt> if the element was added to this deque, else
|
465 |
|
|
* <tt>false</tt>
|
466 |
|
|
* @throws InterruptedException {@inheritDoc}
|
467 |
|
|
* @throws ClassCastException if the class of the specified element
|
468 |
|
|
* prevents it from being added to this deque
|
469 |
|
|
* @throws NullPointerException if the specified element is null
|
470 |
|
|
* @throws IllegalArgumentException if some property of the specified
|
471 |
|
|
* element prevents it from being added to this deque
|
472 |
|
|
*/
|
473 |
|
|
boolean offer(E e, long timeout, TimeUnit unit)
|
474 |
|
|
throws InterruptedException;
|
475 |
|
|
|
476 |
|
|
/**
|
477 |
|
|
* Retrieves and removes the head of the queue represented by this deque
|
478 |
|
|
* (in other words, the first element of this deque).
|
479 |
|
|
* This method differs from {@link #poll poll} only in that it
|
480 |
|
|
* throws an exception if this deque is empty.
|
481 |
|
|
*
|
482 |
|
|
* <p>This method is equivalent to {@link #removeFirst() removeFirst}.
|
483 |
|
|
*
|
484 |
|
|
* @return the head of the queue represented by this deque
|
485 |
|
|
* @throws NoSuchElementException if this deque is empty
|
486 |
|
|
*/
|
487 |
|
|
E remove();
|
488 |
|
|
|
489 |
|
|
/**
|
490 |
|
|
* Retrieves and removes the head of the queue represented by this deque
|
491 |
|
|
* (in other words, the first element of this deque), or returns
|
492 |
|
|
* <tt>null</tt> if this deque is empty.
|
493 |
|
|
*
|
494 |
|
|
* <p>This method is equivalent to {@link #pollFirst()}.
|
495 |
|
|
*
|
496 |
|
|
* @return the head of this deque, or <tt>null</tt> if this deque is empty
|
497 |
|
|
*/
|
498 |
|
|
E poll();
|
499 |
|
|
|
500 |
|
|
/**
|
501 |
|
|
* Retrieves and removes the head of the queue represented by this deque
|
502 |
|
|
* (in other words, the first element of this deque), waiting if
|
503 |
|
|
* necessary until an element becomes available.
|
504 |
|
|
*
|
505 |
|
|
* <p>This method is equivalent to {@link #takeFirst() takeFirst}.
|
506 |
|
|
*
|
507 |
|
|
* @return the head of this deque
|
508 |
|
|
* @throws InterruptedException if interrupted while waiting
|
509 |
|
|
*/
|
510 |
|
|
E take() throws InterruptedException;
|
511 |
|
|
|
512 |
|
|
/**
|
513 |
|
|
* Retrieves and removes the head of the queue represented by this deque
|
514 |
|
|
* (in other words, the first element of this deque), waiting up to the
|
515 |
|
|
* specified wait time if necessary for an element to become available.
|
516 |
|
|
*
|
517 |
|
|
* <p>This method is equivalent to
|
518 |
|
|
* {@link #pollFirst(long,TimeUnit) pollFirst}.
|
519 |
|
|
*
|
520 |
|
|
* @return the head of this deque, or <tt>null</tt> if the
|
521 |
|
|
* specified waiting time elapses before an element is available
|
522 |
|
|
* @throws InterruptedException if interrupted while waiting
|
523 |
|
|
*/
|
524 |
|
|
E poll(long timeout, TimeUnit unit)
|
525 |
|
|
throws InterruptedException;
|
526 |
|
|
|
527 |
|
|
/**
|
528 |
|
|
* Retrieves, but does not remove, the head of the queue represented by
|
529 |
|
|
* this deque (in other words, the first element of this deque).
|
530 |
|
|
* This method differs from {@link #peek peek} only in that it throws an
|
531 |
|
|
* exception if this deque is empty.
|
532 |
|
|
*
|
533 |
|
|
* <p>This method is equivalent to {@link #getFirst() getFirst}.
|
534 |
|
|
*
|
535 |
|
|
* @return the head of this deque
|
536 |
|
|
* @throws NoSuchElementException if this deque is empty
|
537 |
|
|
*/
|
538 |
|
|
E element();
|
539 |
|
|
|
540 |
|
|
/**
|
541 |
|
|
* Retrieves, but does not remove, the head of the queue represented by
|
542 |
|
|
* this deque (in other words, the first element of this deque), or
|
543 |
|
|
* returns <tt>null</tt> if this deque is empty.
|
544 |
|
|
*
|
545 |
|
|
* <p>This method is equivalent to {@link #peekFirst() peekFirst}.
|
546 |
|
|
*
|
547 |
|
|
* @return the head of this deque, or <tt>null</tt> if this deque is empty
|
548 |
|
|
*/
|
549 |
|
|
E peek();
|
550 |
|
|
|
551 |
|
|
/**
|
552 |
|
|
* Removes the first occurrence of the specified element from this deque.
|
553 |
|
|
* If the deque does not contain the element, it is unchanged.
|
554 |
|
|
* More formally, removes the first element <tt>e</tt> such that
|
555 |
|
|
* <tt>o.equals(e)</tt> (if such an element exists).
|
556 |
|
|
* Returns <tt>true</tt> if this deque contained the specified element
|
557 |
|
|
* (or equivalently, if this deque changed as a result of the call).
|
558 |
|
|
*
|
559 |
|
|
* <p>This method is equivalent to
|
560 |
|
|
* {@link #removeFirstOccurrence(Object) removeFirstOccurrence}.
|
561 |
|
|
*
|
562 |
|
|
* @param o element to be removed from this deque, if present
|
563 |
|
|
* @return <tt>true</tt> if this deque changed as a result of the call
|
564 |
|
|
* @throws ClassCastException if the class of the specified element
|
565 |
|
|
* is incompatible with this deque (optional)
|
566 |
|
|
* @throws NullPointerException if the specified element is null (optional)
|
567 |
|
|
*/
|
568 |
|
|
boolean remove(Object o);
|
569 |
|
|
|
570 |
|
|
/**
|
571 |
|
|
* Returns <tt>true</tt> if this deque contains the specified element.
|
572 |
|
|
* More formally, returns <tt>true</tt> if and only if this deque contains
|
573 |
|
|
* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
|
574 |
|
|
*
|
575 |
|
|
* @param o object to be checked for containment in this deque
|
576 |
|
|
* @return <tt>true</tt> if this deque contains the specified element
|
577 |
|
|
* @throws ClassCastException if the class of the specified element
|
578 |
|
|
* is incompatible with this deque (optional)
|
579 |
|
|
* @throws NullPointerException if the specified element is null (optional)
|
580 |
|
|
*/
|
581 |
|
|
public boolean contains(Object o);
|
582 |
|
|
|
583 |
|
|
/**
|
584 |
|
|
* Returns the number of elements in this deque.
|
585 |
|
|
*
|
586 |
|
|
* @return the number of elements in this deque
|
587 |
|
|
*/
|
588 |
|
|
public int size();
|
589 |
|
|
|
590 |
|
|
/**
|
591 |
|
|
* Returns an iterator over the elements in this deque in proper sequence.
|
592 |
|
|
* The elements will be returned in order from first (head) to last (tail).
|
593 |
|
|
*
|
594 |
|
|
* @return an iterator over the elements in this deque in proper sequence
|
595 |
|
|
*/
|
596 |
|
|
Iterator<E> iterator();
|
597 |
|
|
|
598 |
|
|
// *** Stack methods ***
|
599 |
|
|
|
600 |
|
|
/**
|
601 |
|
|
* Pushes an element onto the stack represented by this deque. In other
|
602 |
|
|
* words, inserts the element at the front of this deque unless it would
|
603 |
|
|
* violate capacity restrictions.
|
604 |
|
|
*
|
605 |
|
|
* <p>This method is equivalent to {@link #addFirst(Object) addFirst}.
|
606 |
|
|
*
|
607 |
|
|
* @throws IllegalStateException {@inheritDoc}
|
608 |
|
|
* @throws ClassCastException {@inheritDoc}
|
609 |
|
|
* @throws NullPointerException if the specified element is null
|
610 |
|
|
* @throws IllegalArgumentException {@inheritDoc}
|
611 |
|
|
*/
|
612 |
|
|
void push(E e);
|
613 |
|
|
}
|