/* |
|
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
|
* |
|
* This code is free software; you can redistribute it and/or modify it |
|
* under the terms of the GNU General Public License version 2 only, as |
|
* published by the Free Software Foundation. Oracle designates this |
|
* particular file as subject to the "Classpath" exception as provided |
|
* by Oracle in the LICENSE file that accompanied this code. |
|
* |
|
* This code is distributed in the hope that it will be useful, but WITHOUT |
|
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
|
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
|
* version 2 for more details (a copy is included in the LICENSE file that |
|
* accompanied this code). |
|
* |
|
* You should have received a copy of the GNU General Public License version |
|
* 2 along with this work; if not, write to the Free Software Foundation, |
|
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
|
* |
|
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
|
* or visit www.oracle.com if you need additional information or have any |
|
* questions. |
|
*/ |
|
/* |
|
* This file is available under and governed by the GNU General Public |
|
* License version 2 only, as published by the Free Software Foundation. |
|
* However, the following notice accompanied the original version of this |
|
* file: |
|
* |
|
* Written by Doug Lea with assistance from members of JCP JSR-166 |
|
* Expert Group and released to the public domain, as explained at |
|
* http://creativecommons.org/publicdomain/zero/1.0/ |
|
*/ |
|
package java.util.concurrent; |
|
import java.util.Deque; |
|
import java.util.Iterator; |
|
import java.util.NoSuchElementException; |
|
/** |
|
* A {@link Deque} that additionally supports blocking operations that wait |
|
* for the deque to become non-empty when retrieving an element, and wait for |
|
* space to become available in the deque when storing an element. |
|
* |
|
* <p>{@code BlockingDeque} methods come in four forms, with different ways |
|
* of handling operations that cannot be satisfied immediately, but may be |
|
* satisfied at some point in the future: |
|
* one throws an exception, the second returns a special value (either |
|
* {@code null} or {@code false}, depending on the operation), the third |
|
* blocks the current thread indefinitely until the operation can succeed, |
|
* and the fourth blocks for only a given maximum time limit before giving |
|
* up. These methods are summarized in the following table: |
|
* |
|
* <table class="plain"> |
|
* <caption>Summary of BlockingDeque methods</caption> |
|
* <tr> |
|
* <th id="First" colspan="5"> First Element (Head)</th> |
|
* </tr> |
|
* <tr> |
|
* <td></td> |
|
* <th id="FThrow" style="font-weight:normal; font-style: italic">Throws exception</th> |
|
* <th id="FValue" style="font-weight:normal; font-style: italic">Special value</th> |
|
* <th id="FBlock" style="font-weight:normal; font-style: italic">Blocks</th> |
|
* <th id="FTimes" style="font-weight:normal; font-style: italic">Times out</th> |
|
* </tr> |
|
* <tr> |
|
* <th id="FInsert" style="text-align:left">Insert</th> |
|
* <td headers="First FInsert FThrow">{@link #addFirst(Object) addFirst(e)}</td> |
|
* <td headers="First FInsert FValue">{@link #offerFirst(Object) offerFirst(e)}</td> |
|
* <td headers="First FInsert FBlock">{@link #putFirst(Object) putFirst(e)}</td> |
|
* <td headers="First FInsert FTimes">{@link #offerFirst(Object, long, TimeUnit) offerFirst(e, time, unit)}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="FRemove" style="text-align:left">Remove</th> |
|
* <td headers="First FRemove FThrow">{@link #removeFirst() removeFirst()}</td> |
|
* <td headers="First FRemove FValue">{@link #pollFirst() pollFirst()}</td> |
|
* <td headers="First FRemove FBlock">{@link #takeFirst() takeFirst()}</td> |
|
* <td headers="First FRemove FTimes">{@link #pollFirst(long, TimeUnit) pollFirst(time, unit)}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="FExamine" style="text-align:left">Examine</th> |
|
* <td headers="First FExamine FThrow">{@link #getFirst() getFirst()}</td> |
|
* <td headers="First FExamine FValue">{@link #peekFirst() peekFirst()}</td> |
|
* <td headers="First FExamine FBlock" style="font-style:italic">not applicable</td> |
|
* <td headers="First FExamine FTimes" style="font-style:italic">not applicable</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="Last" colspan="5"> Last Element (Tail)</th> |
|
* </tr> |
|
* <tr> |
|
* <td></td> |
|
* <th id="LThrow" style="font-weight:normal; font-style: italic">Throws exception</th> |
|
* <th id="LValue" style="font-weight:normal; font-style: italic">Special value</th> |
|
* <th id="LBlock" style="font-weight:normal; font-style: italic">Blocks</th> |
|
* <th id="LTimes" style="font-weight:normal; font-style: italic">Times out</th> |
|
* </tr> |
|
* <tr> |
|
* <th id="LInsert" style="text-align:left">Insert</th> |
|
* <td headers="Last LInsert LThrow">{@link #addLast(Object) addLast(e)}</td> |
|
* <td headers="Last LInsert LValue">{@link #offerLast(Object) offerLast(e)}</td> |
|
* <td headers="Last LInsert LBlock">{@link #putLast(Object) putLast(e)}</td> |
|
* <td headers="Last LInsert LTimes">{@link #offerLast(Object, long, TimeUnit) offerLast(e, time, unit)}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="LRemove" style="text-align:left">Remove</th> |
|
* <td headers="Last LRemove LThrow">{@link #removeLast() removeLast()}</td> |
|
* <td headers="Last LRemove LValue">{@link #pollLast() pollLast()}</td> |
|
* <td headers="Last LRemove LBlock">{@link #takeLast() takeLast()}</td> |
|
* <td headers="Last LRemove LTimes">{@link #pollLast(long, TimeUnit) pollLast(time, unit)}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="LExamine" style="text-align:left">Examine</th> |
|
* <td headers="Last LExamine LThrow">{@link #getLast() getLast()}</td> |
|
* <td headers="Last LExamine LValue">{@link #peekLast() peekLast()}</td> |
|
* <td headers="Last LExamine LBlock" style="font-style:italic">not applicable</td> |
|
* <td headers="Last LExamine LTimes" style="font-style:italic">not applicable</td> |
|
* </tr> |
|
* </table> |
|
* |
|
* <p>Like any {@link BlockingQueue}, a {@code BlockingDeque} is thread safe, |
|
* does not permit null elements, and may (or may not) be |
|
* capacity-constrained. |
|
* |
|
* <p>A {@code BlockingDeque} implementation may be used directly as a FIFO |
|
* {@code BlockingQueue}. The methods inherited from the |
|
* {@code BlockingQueue} interface are precisely equivalent to |
|
* {@code BlockingDeque} methods as indicated in the following table: |
|
* |
|
* <table class="plain"> |
|
* <caption>Comparison of BlockingQueue and BlockingDeque methods</caption> |
|
* <tr> |
|
* <td></td> |
|
* <th id="BQueue"> {@code BlockingQueue} Method</th> |
|
* <th id="BDeque"> Equivalent {@code BlockingDeque} Method</th> |
|
* </tr> |
|
* <tr> |
|
* <th id="Insert" rowspan="4" style="text-align:left; vertical-align:top">Insert</th> |
|
* <th id="add" style="font-weight:normal; text-align:left">{@link #add(Object) add(e)}</th> |
|
* <td headers="Insert BDeque add">{@link #addLast(Object) addLast(e)}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="offer1" style="font-weight:normal; text-align:left">{@link #offer(Object) offer(e)}</th> |
|
* <td headers="Insert BDeque offer1">{@link #offerLast(Object) offerLast(e)}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="put" style="font-weight:normal; text-align:left">{@link #put(Object) put(e)}</th> |
|
* <td headers="Insert BDeque put">{@link #putLast(Object) putLast(e)}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="offer2" style="font-weight:normal; text-align:left">{@link #offer(Object, long, TimeUnit) offer(e, time, unit)}</th> |
|
* <td headers="Insert BDeque offer2">{@link #offerLast(Object, long, TimeUnit) offerLast(e, time, unit)}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="Remove" rowspan="4" style="text-align:left; vertical-align:top">Remove</th> |
|
* <th id="remove" style="font-weight:normal; text-align:left">{@link #remove() remove()}</th> |
|
* <td headers="Remove BDeque remove">{@link #removeFirst() removeFirst()}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="poll1" style="font-weight:normal; text-align:left">{@link #poll() poll()}</th> |
|
* <td headers="Remove BDeque poll1">{@link #pollFirst() pollFirst()}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="take" style="font-weight:normal; text-align:left">{@link #take() take()}</th> |
|
* <td headers="Remove BDeque take">{@link #takeFirst() takeFirst()}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="poll2" style="font-weight:normal; text-align:left">{@link #poll(long, TimeUnit) poll(time, unit)}</th> |
|
* <td headers="Remove BDeque poll2">{@link #pollFirst(long, TimeUnit) pollFirst(time, unit)}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="Examine" rowspan="2" style="text-align:left; vertical-align:top">Examine</th> |
|
* <th id="element" style="font-weight:normal; text-align:left">{@link #element() element()}</th> |
|
* <td headers="Examine BDeque element">{@link #getFirst() getFirst()}</td> |
|
* </tr> |
|
* <tr> |
|
* <th id="peek" style="font-weight:normal; text-align:left">{@link #peek() peek()}</th> |
|
* <td headers="Examine BDeque peek">{@link #peekFirst() peekFirst()}</td> |
|
* </tr> |
|
* </table> |
|
* |
|
* <p>Memory consistency effects: As with other concurrent |
|
* collections, actions in a thread prior to placing an object into a |
|
* {@code BlockingDeque} |
|
* <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a> |
|
* actions subsequent to the access or removal of that element from |
|
* the {@code BlockingDeque} in another thread. |
|
* |
|
* <p>This interface is a member of the |
|
* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework"> |
|
* Java Collections Framework</a>. |
|
* |
|
* @since 1.6 |
|
* @author Doug Lea |
|
* @param <E> the type of elements held in this deque |
|
*/ |
|
public interface BlockingDeque<E> extends BlockingQueue<E>, Deque<E> { |
|
/* |
|
* We have "diamond" multiple interface inheritance here, and that |
|
* introduces ambiguities. Methods might end up with different |
|
* specs depending on the branch chosen by javadoc. Thus a lot of |
|
* methods specs here are copied from superinterfaces. |
|
*/ |
|
/** |
|
* Inserts the specified element at the front of this deque if it is |
|
* possible to do so immediately without violating capacity restrictions, |
|
* throwing an {@code IllegalStateException} if no space is currently |
|
* available. When using a capacity-restricted deque, it is generally |
|
* preferable to use {@link #offerFirst(Object) offerFirst}. |
|
* |
|
* @param e the element to add |
|
* @throws IllegalStateException {@inheritDoc} |
|
* @throws ClassCastException {@inheritDoc} |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException {@inheritDoc} |
|
*/ |
|
void addFirst(E e); |
|
/** |
|
* Inserts the specified element at the end of this deque if it is |
|
* possible to do so immediately without violating capacity restrictions, |
|
* throwing an {@code IllegalStateException} if no space is currently |
|
* available. When using a capacity-restricted deque, it is generally |
|
* preferable to use {@link #offerLast(Object) offerLast}. |
|
* |
|
* @param e the element to add |
|
* @throws IllegalStateException {@inheritDoc} |
|
* @throws ClassCastException {@inheritDoc} |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException {@inheritDoc} |
|
*/ |
|
void addLast(E e); |
|
/** |
|
* Inserts the specified element at the front of this deque if it is |
|
* possible to do so immediately without violating capacity restrictions, |
|
* returning {@code true} upon success and {@code false} if no space is |
|
* currently available. |
|
* When using a capacity-restricted deque, this method is generally |
|
* preferable to the {@link #addFirst(Object) addFirst} method, which can |
|
* fail to insert an element only by throwing an exception. |
|
* |
|
* @param e the element to add |
|
* @throws ClassCastException {@inheritDoc} |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException {@inheritDoc} |
|
*/ |
|
boolean offerFirst(E e); |
|
/** |
|
* Inserts the specified element at the end of this deque if it is |
|
* possible to do so immediately without violating capacity restrictions, |
|
* returning {@code true} upon success and {@code false} if no space is |
|
* currently available. |
|
* When using a capacity-restricted deque, this method is generally |
|
* preferable to the {@link #addLast(Object) addLast} method, which can |
|
* fail to insert an element only by throwing an exception. |
|
* |
|
* @param e the element to add |
|
* @throws ClassCastException {@inheritDoc} |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException {@inheritDoc} |
|
*/ |
|
boolean offerLast(E e); |
|
/** |
|
* Inserts the specified element at the front of this deque, |
|
* waiting if necessary for space to become available. |
|
* |
|
* @param e the element to add |
|
* @throws InterruptedException if interrupted while waiting |
|
* @throws ClassCastException if the class of the specified element |
|
* prevents it from being added to this deque |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException if some property of the specified |
|
* element prevents it from being added to this deque |
|
*/ |
|
void putFirst(E e) throws InterruptedException; |
|
/** |
|
* Inserts the specified element at the end of this deque, |
|
* waiting if necessary for space to become available. |
|
* |
|
* @param e the element to add |
|
* @throws InterruptedException if interrupted while waiting |
|
* @throws ClassCastException if the class of the specified element |
|
* prevents it from being added to this deque |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException if some property of the specified |
|
* element prevents it from being added to this deque |
|
*/ |
|
void putLast(E e) throws InterruptedException; |
|
/** |
|
* Inserts the specified element at the front of this deque, |
|
* waiting up to the specified wait time if necessary for space to |
|
* become available. |
|
* |
|
* @param e the element to add |
|
* @param timeout how long to wait before giving up, in units of |
|
* {@code unit} |
|
* @param unit a {@code TimeUnit} determining how to interpret the |
|
* {@code timeout} parameter |
|
* @return {@code true} if successful, or {@code false} if |
|
* the specified waiting time elapses before space is available |
|
* @throws InterruptedException if interrupted while waiting |
|
* @throws ClassCastException if the class of the specified element |
|
* prevents it from being added to this deque |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException if some property of the specified |
|
* element prevents it from being added to this deque |
|
*/ |
|
boolean offerFirst(E e, long timeout, TimeUnit unit) |
|
throws InterruptedException; |
|
/** |
|
* Inserts the specified element at the end of this deque, |
|
* waiting up to the specified wait time if necessary for space to |
|
* become available. |
|
* |
|
* @param e the element to add |
|
* @param timeout how long to wait before giving up, in units of |
|
* {@code unit} |
|
* @param unit a {@code TimeUnit} determining how to interpret the |
|
* {@code timeout} parameter |
|
* @return {@code true} if successful, or {@code false} if |
|
* the specified waiting time elapses before space is available |
|
* @throws InterruptedException if interrupted while waiting |
|
* @throws ClassCastException if the class of the specified element |
|
* prevents it from being added to this deque |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException if some property of the specified |
|
* element prevents it from being added to this deque |
|
*/ |
|
boolean offerLast(E e, long timeout, TimeUnit unit) |
|
throws InterruptedException; |
|
/** |
|
* Retrieves and removes the first element of this deque, waiting |
|
* if necessary until an element becomes available. |
|
* |
|
* @return the head of this deque |
|
* @throws InterruptedException if interrupted while waiting |
|
*/ |
|
E takeFirst() throws InterruptedException; |
|
/** |
|
* Retrieves and removes the last element of this deque, waiting |
|
* if necessary until an element becomes available. |
|
* |
|
* @return the tail of this deque |
|
* @throws InterruptedException if interrupted while waiting |
|
*/ |
|
E takeLast() throws InterruptedException; |
|
/** |
|
* Retrieves and removes the first element of this deque, waiting |
|
* up to the specified wait time if necessary for an element to |
|
* become available. |
|
* |
|
* @param timeout how long to wait before giving up, in units of |
|
* {@code unit} |
|
* @param unit a {@code TimeUnit} determining how to interpret the |
|
* {@code timeout} parameter |
|
* @return the head of this deque, or {@code null} if the specified |
|
* waiting time elapses before an element is available |
|
* @throws InterruptedException if interrupted while waiting |
|
*/ |
|
E pollFirst(long timeout, TimeUnit unit) |
|
throws InterruptedException; |
|
/** |
|
* Retrieves and removes the last element of this deque, waiting |
|
* up to the specified wait time if necessary for an element to |
|
* become available. |
|
* |
|
* @param timeout how long to wait before giving up, in units of |
|
* {@code unit} |
|
* @param unit a {@code TimeUnit} determining how to interpret the |
|
* {@code timeout} parameter |
|
* @return the tail of this deque, or {@code null} if the specified |
|
* waiting time elapses before an element is available |
|
* @throws InterruptedException if interrupted while waiting |
|
*/ |
|
E pollLast(long timeout, TimeUnit unit) |
|
throws InterruptedException; |
|
/** |
|
* Removes the first occurrence of the specified element from this deque. |
|
* If the deque does not contain the element, it is unchanged. |
|
* More formally, removes the first element {@code e} such that |
|
* {@code o.equals(e)} (if such an element exists). |
|
* Returns {@code true} if this deque contained the specified element |
|
* (or equivalently, if this deque changed as a result of the call). |
|
* |
|
* @param o element to be removed from this deque, if present |
|
* @return {@code true} if an element was removed as a result of this call |
|
* @throws ClassCastException if the class of the specified element |
|
* is incompatible with this deque |
|
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
|
* @throws NullPointerException if the specified element is null |
|
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
|
*/ |
|
boolean removeFirstOccurrence(Object o); |
|
/** |
|
* Removes the last occurrence of the specified element from this deque. |
|
* If the deque does not contain the element, it is unchanged. |
|
* More formally, removes the last element {@code e} such that |
|
* {@code o.equals(e)} (if such an element exists). |
|
* Returns {@code true} if this deque contained the specified element |
|
* (or equivalently, if this deque changed as a result of the call). |
|
* |
|
* @param o element to be removed from this deque, if present |
|
* @return {@code true} if an element was removed as a result of this call |
|
* @throws ClassCastException if the class of the specified element |
|
* is incompatible with this deque |
|
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
|
* @throws NullPointerException if the specified element is null |
|
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
|
*/ |
|
boolean removeLastOccurrence(Object o); |
|
// *** BlockingQueue methods *** |
|
/** |
|
* Inserts the specified element into the queue represented by this deque |
|
* (in other words, at the tail of this deque) if it is possible to do so |
|
* immediately without violating capacity restrictions, returning |
|
* {@code true} upon success and throwing an |
|
* {@code IllegalStateException} if no space is currently available. |
|
* When using a capacity-restricted deque, it is generally preferable to |
|
* use {@link #offer(Object) offer}. |
|
* |
|
* <p>This method is equivalent to {@link #addLast(Object) addLast}. |
|
* |
|
* @param e the element to add |
|
* @throws IllegalStateException {@inheritDoc} |
|
* @throws ClassCastException if the class of the specified element |
|
* prevents it from being added to this deque |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException if some property of the specified |
|
* element prevents it from being added to this deque |
|
*/ |
|
boolean add(E e); |
|
/** |
|
* Inserts the specified element into the queue represented by this deque |
|
* (in other words, at the tail of this deque) if it is possible to do so |
|
* immediately without violating capacity restrictions, returning |
|
* {@code true} upon success and {@code false} if no space is currently |
|
* available. When using a capacity-restricted deque, this method is |
|
* generally preferable to the {@link #add} method, which can fail to |
|
* insert an element only by throwing an exception. |
|
* |
|
* <p>This method is equivalent to {@link #offerLast(Object) offerLast}. |
|
* |
|
* @param e the element to add |
|
* @throws ClassCastException if the class of the specified element |
|
* prevents it from being added to this deque |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException if some property of the specified |
|
* element prevents it from being added to this deque |
|
*/ |
|
boolean offer(E e); |
|
/** |
|
* Inserts the specified element into the queue represented by this deque |
|
* (in other words, at the tail of this deque), waiting if necessary for |
|
* space to become available. |
|
* |
|
* <p>This method is equivalent to {@link #putLast(Object) putLast}. |
|
* |
|
* @param e the element to add |
|
* @throws InterruptedException {@inheritDoc} |
|
* @throws ClassCastException if the class of the specified element |
|
* prevents it from being added to this deque |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException if some property of the specified |
|
* element prevents it from being added to this deque |
|
*/ |
|
void put(E e) throws InterruptedException; |
|
/** |
|
* Inserts the specified element into the queue represented by this deque |
|
* (in other words, at the tail of this deque), waiting up to the |
|
* specified wait time if necessary for space to become available. |
|
* |
|
* <p>This method is equivalent to |
|
* {@link #offerLast(Object,long,TimeUnit) offerLast}. |
|
* |
|
* @param e the element to add |
|
* @return {@code true} if the element was added to this deque, else |
|
* {@code false} |
|
* @throws InterruptedException {@inheritDoc} |
|
* @throws ClassCastException if the class of the specified element |
|
* prevents it from being added to this deque |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException if some property of the specified |
|
* element prevents it from being added to this deque |
|
*/ |
|
boolean offer(E e, long timeout, TimeUnit unit) |
|
throws InterruptedException; |
|
/** |
|
* Retrieves and removes the head of the queue represented by this deque |
|
* (in other words, the first element of this deque). |
|
* This method differs from {@link #poll() poll()} only in that it |
|
* throws an exception if this deque is empty. |
|
* |
|
* <p>This method is equivalent to {@link #removeFirst() removeFirst}. |
|
* |
|
* @return the head of the queue represented by this deque |
|
* @throws NoSuchElementException if this deque is empty |
|
*/ |
|
E remove(); |
|
/** |
|
* Retrieves and removes the head of the queue represented by this deque |
|
* (in other words, the first element of this deque), or returns |
|
* {@code null} if this deque is empty. |
|
* |
|
* <p>This method is equivalent to {@link #pollFirst()}. |
|
* |
|
* @return the head of this deque, or {@code null} if this deque is empty |
|
*/ |
|
E poll(); |
|
/** |
|
* Retrieves and removes the head of the queue represented by this deque |
|
* (in other words, the first element of this deque), waiting if |
|
* necessary until an element becomes available. |
|
* |
|
* <p>This method is equivalent to {@link #takeFirst() takeFirst}. |
|
* |
|
* @return the head of this deque |
|
* @throws InterruptedException if interrupted while waiting |
|
*/ |
|
E take() throws InterruptedException; |
|
/** |
|
* Retrieves and removes the head of the queue represented by this deque |
|
* (in other words, the first element of this deque), waiting up to the |
|
* specified wait time if necessary for an element to become available. |
|
* |
|
* <p>This method is equivalent to |
|
* {@link #pollFirst(long,TimeUnit) pollFirst}. |
|
* |
|
* @return the head of this deque, or {@code null} if the |
|
* specified waiting time elapses before an element is available |
|
* @throws InterruptedException if interrupted while waiting |
|
*/ |
|
E poll(long timeout, TimeUnit unit) |
|
throws InterruptedException; |
|
/** |
|
* Retrieves, but does not remove, the head of the queue represented by |
|
* this deque (in other words, the first element of this deque). |
|
* This method differs from {@link #peek() peek} only in that it throws an |
|
* exception if this deque is empty. |
|
* |
|
* <p>This method is equivalent to {@link #getFirst() getFirst}. |
|
* |
|
* @return the head of this deque |
|
* @throws NoSuchElementException if this deque is empty |
|
*/ |
|
E element(); |
|
/** |
|
* Retrieves, but does not remove, the head of the queue represented by |
|
* this deque (in other words, the first element of this deque), or |
|
* returns {@code null} if this deque is empty. |
|
* |
|
* <p>This method is equivalent to {@link #peekFirst() peekFirst}. |
|
* |
|
* @return the head of this deque, or {@code null} if this deque is empty |
|
*/ |
|
E peek(); |
|
/** |
|
* Removes the first occurrence of the specified element from this deque. |
|
* If the deque does not contain the element, it is unchanged. |
|
* More formally, removes the first element {@code e} such that |
|
* {@code o.equals(e)} (if such an element exists). |
|
* Returns {@code true} if this deque contained the specified element |
|
* (or equivalently, if this deque changed as a result of the call). |
|
* |
|
* <p>This method is equivalent to |
|
* {@link #removeFirstOccurrence(Object) removeFirstOccurrence}. |
|
* |
|
* @param o element to be removed from this deque, if present |
|
* @return {@code true} if this deque changed as a result of the call |
|
* @throws ClassCastException if the class of the specified element |
|
* is incompatible with this deque |
|
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
|
* @throws NullPointerException if the specified element is null |
|
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
|
*/ |
|
boolean remove(Object o); |
|
/** |
|
* Returns {@code true} if this deque contains the specified element. |
|
* More formally, returns {@code true} if and only if this deque contains |
|
* at least one element {@code e} such that {@code o.equals(e)}. |
|
* |
|
* @param o object to be checked for containment in this deque |
|
* @return {@code true} if this deque contains the specified element |
|
* @throws ClassCastException if the class of the specified element |
|
* is incompatible with this deque |
|
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
|
* @throws NullPointerException if the specified element is null |
|
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
|
*/ |
|
boolean contains(Object o); |
|
/** |
|
* Returns the number of elements in this deque. |
|
* |
|
* @return the number of elements in this deque |
|
*/ |
|
int size(); |
|
/** |
|
* Returns an iterator over the elements in this deque in proper sequence. |
|
* The elements will be returned in order from first (head) to last (tail). |
|
* |
|
* @return an iterator over the elements in this deque in proper sequence |
|
*/ |
|
Iterator<E> iterator(); |
|
// *** Stack methods *** |
|
/** |
|
* Pushes an element onto the stack represented by this deque (in other |
|
* words, at the head of this deque) if it is possible to do so |
|
* immediately without violating capacity restrictions, throwing an |
|
* {@code IllegalStateException} if no space is currently available. |
|
* |
|
* <p>This method is equivalent to {@link #addFirst(Object) addFirst}. |
|
* |
|
* @throws IllegalStateException {@inheritDoc} |
|
* @throws ClassCastException {@inheritDoc} |
|
* @throws NullPointerException if the specified element is null |
|
* @throws IllegalArgumentException {@inheritDoc} |
|
*/ |
|
void push(E e); |
|
} |