blocks|key|1044487|text|Queue是一个接口，这意味着您不能直接构造Queue。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1044488|最好的选择是构造一个已经实现了Queue接口的类，如以下类之一：AbstractQueue、ArrayBlockingQueue、ArrayDeque、ConcurrentLinkedQueue、DelayQueue、LinkedBlockingQueue、LinkedList、PriorityBlockingQueue、PriorityQueue或SynchronousQueue。|1044489|另一种方法是编写您自己的类，实现必要的Queue接口。除非在极少数情况下，您希望在为程序的其余部分提供Queue的同时做一些特殊的事情，否则不需要它。|1044490|public+class+MyQueue<T+extends+Tree>+implements+Queue<T>+{
+++public+T+element()+{
+++++...+your+code+to+return+an+element+goes+here+...
+++}

+++public+boolean+offer(T+element)+{
+++++...+your+code+to+accept+a+submission+offer+goes+here+...
+++}

+++...+etc+...
}|code-block|syntax|javascript|1044491|一种更少使用的替代方法是构造一个实现Queue的匿名类。你可能不想这样做，但为了覆盖所有的基础，它被列为一个选项。|1044492|new+Queue<Tree>()+{
+++public+Tree+element()+{
+++++...
+++};

+++public+boolean+offer(Tree+element)+{
+++++...
+++};
+++...
};|1044493|entityMap^0|0|5|M|5|0|F|5|W|D|1A|I|1T|A|24|L|2Q|A|31|J|3L|A|3W|L|4I|D|4W|G|0|1F|5|0|0|I|5|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@$9|10|A|11|B|C]|$9|12|A|13|B|C]|$9|14|A|15|B|C]|$9|16|A|17|B|C]|$9|18|A|19|B|C]|$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]|$9|1I|A|1J|B|C]|$9|1K|A|1L|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1M|8|@$9|1N|A|1O|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|1P|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1Q|8|@$9|1R|A|1S|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|L|7|1T|8|@]|D|@]|E|$M|N]]|$1|S|3|-4|5|6|7|1U|8|@]|D|@]|E|$]]]|T|$]]

A <code>Queue</code> is an interface, which means you cannot construct a <code>Queue</code> directly.

The best option is to construct off a class that already implements the <code>Queue</code> interface, like one of the following: <code>AbstractQueue</code>, <code>ArrayBlockingQueue</code>, <code>ArrayDeque</code>, <code>ConcurrentLinkedQueue</code>, <code>DelayQueue</code>, <code>LinkedBlockingQueue</code>, <code>LinkedList</code>, <code>PriorityBlockingQueue</code>, <code>PriorityQueue</code>, or <code>SynchronousQueue</code>.

An alternative is to write your own class which implements the necessary Queue interface. It is not needed except in those rare cases where you wish to do something special while providing the rest of your program with a <code>Queue</code>.

<pre><code>public class MyQueue&lt;T extends Tree&gt; implements Queue&lt;T&gt; {
 public T element() {
 ... your code to return an element goes here ...
 }

 public boolean offer(T element) {
 ... your code to accept a submission offer goes here ...
 }

 ... etc ...
}
</code></pre>

An even less used alternative is to construct an anonymous class that implements <code>Queue</code>. You probably don't want to do this, but it's listed as an option for the sake of covering all the bases.

<pre><code>new Queue&lt;Tree&gt;() {
 public Tree element() {
 ...
 };

 public boolean offer(Tree element) {
 ...
 };
 ...
};
</code></pre>

blocks|key|1044393|text|Queue<String>+qe=new+LinkedList<String>();

qe.add("b");
qe.add("a");
qe.add("c");|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1044394|因为Queue是一个接口，所以您不能像前面说明的那样创建它的实例|unstyled|offset|length|style|CODE|1044395|entityMap|0|LINK|mutability|MUTABLE|url|http://download.oracle.com/javase/6/docs/api/java/util/Queue.html^0|0|2|5|2|5|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|T|8|@$G|U|H|V|I|J]]|9|@$G|W|H|X|1|Y]]|A|$]]|$1|K|3|-4|5|F|7|Z|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

<pre><code>Queue&lt;String&gt; qe=new LinkedList&lt;String&gt;();

qe.add("b");
qe.add("a");
qe.add("c");
</code></pre>

Since <a href="http://download.oracle.com/javase/6/docs/api/java/util/Queue.html" rel="noreferrer"><code>Queue</code></a> is an interface, you can't create an instance of it as you illustrated

blocks|key|1044504|text|Queue是一个接口；您不能显式构造一个队列。您必须实例化它的一个实现类。类似于：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1044505|Queue+linkedList+=+new+LinkedList();|code-block|syntax|javascript|1044506|Here's+a+link+to+the+Java+tutorial+on+this+subject.|offset|length|1044507|entityMap|0|LINK|mutability|MUTABLE|url|http://download.oracle.com/javase/tutorial/java/concepts/interface.html^0|0|0|0|1F|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

Queue is an interface; you can't explicitly construct a Queue. You'll have to instantiate one of its implementing classes. Something like:

<pre><code>Queue linkedList = new LinkedList();
</code></pre>

<a href="http://download.oracle.com/javase/tutorial/java/concepts/interface.html" rel="nofollow noreferrer">Here's a link to the Java tutorial on this subject.</a>

blocks|key|829682|text|队列是java中的一个接口，你不能这样做。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|829683|相反，您有两个选择：|829684|option1：|829685|Queue<Integer>+Q+=+new+LinkedList<>();|code-block|syntax|javascript|829686|option2：|829687|Queue<Integer>+Q+=+new+ArrayDeque<>();|829688|我推荐使用option2，因为它比其他的快一点|829689|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|U|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|V|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|H|7|X|8|@]|9|@]|A|$I|J]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

Queue is an interface in java, you can not do that.

Instead you have two options:

option1:

<pre><code>Queue&lt;Integer&gt; Q = new LinkedList&lt;&gt;();
</code></pre>

option2:

<pre><code>Queue&lt;Integer&gt; Q = new ArrayDeque&lt;&gt;();
</code></pre>

I recommend using option2 as it is bit faster than the other

blocks|key|829755|text|Queue+in+Java被定义为一个接口，许多现成的实现都是作为JDK版本的一部分出现的。这里有：LinkedList，优先级队列，ArrayBlockingQueue，ConcurrentLinkedQueue，链接传输队列，Synchronous+Queue等。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|829756|因此您可以创建这些类中任何一个，并将其保存为队列引用。例如|829757|import+java.util.LinkedList;
import+java.util.Queue;

public+class+QueueExample+{

+public+static+void+main+(String[]+args)+{
++Queue+que+=+new+LinkedList();
++que.add("first");
++que.offer("second");
++que.offer("third");
++System.out.println("Queue+Print::+"+%2B+que);
++
++String+head+=+que.element();
++System.out.println("Head+element::+"+%2B+head);
++
++String+element1+=+que.poll();
++System.out.println("Removed+Element::+"+%2B+element1);
++
++System.out.println("Queue+Print+after+poll::+"+%2B+que);
++String+element2+=+que.remove();
++System.out.println("Removed+Element::+"+%2B+element2);
++
++System.out.println("Queue+Print+after+remove::+"+%2B+que);++
+}
}|code-block|syntax|javascript|829758|您还可以实现自己的自定义队列实现Queue接口。|829759|entityMap|0|LINK|mutability|MUTABLE|url|https://web.archive.org/web/20180508024116/http://singletonjava.blogspot.com:80/2016/03/java-queue-example.html|1|https://docs.oracle.com/javase/7/docs/api/java/util/LinkedList.html|2|https://web.archive.org/web/20170830095206/http://singletonjava.blogspot.com/2016/02/java-synchronousqueue-synchronous-queue.html^0|0|D|0|1E|A|1|37|H|2|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@$A|Z|B|10|1|11]|$A|12|B|13|1|14]|$A|15|B|16|1|17]]|C|$]]|$1|D|3|E|5|6|7|18|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|19|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|1A|8|@]|9|@]|C|$]]|$1|M|3|-4|5|6|7|1B|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]|U|$5|P|Q|R|C|$S|V]]|W|$5|P|Q|R|C|$S|X]]]]

<a href="https://web.archive.org/web/20180508024116/http://singletonjava.blogspot.com:80/2016/03/java-queue-example.html" rel="nofollow noreferrer">Queue in Java</a> is defined as an interface and many ready-to-use implementation is present as part of JDK release.
Here are some:
<a href="https://docs.oracle.com/javase/7/docs/api/java/util/LinkedList.html" rel="nofollow noreferrer">LinkedList</a>, Priority Queue, ArrayBlockingQueue, ConcurrentLinkedQueue, Linked Transfer Queue, <a href="https://web.archive.org/web/20170830095206/http://singletonjava.blogspot.com/2016/02/java-synchronousqueue-synchronous-queue.html" rel="nofollow noreferrer">Synchronous Queue</a> etc.
SO You can create any of these class and hold it as Queue reference. for example
<pre><code>import java.util.LinkedList;
import java.util.Queue;

public class QueueExample {

 public static void main (String[] args) {
 Queue que = new LinkedList();
 que.add(&quot;first&quot;);
 que.offer(&quot;second&quot;);
 que.offer(&quot;third&quot;);
 System.out.println(&quot;Queue Print:: &quot; + que);
 
 String head = que.element();
 System.out.println(&quot;Head element:: &quot; + head);
 
 String element1 = que.poll();
 System.out.println(&quot;Removed Element:: &quot; + element1);
 
 System.out.println(&quot;Queue Print after poll:: &quot; + que);
 String element2 = que.remove();
 System.out.println(&quot;Removed Element:: &quot; + element2);
 
 System.out.println(&quot;Queue Print after remove:: &quot; + que); 
 }
}
</code></pre>
You can also implement your own custom Queue implementing Queue interface.

blocks|key|1044543|text|Queue是java中的一个接口，你不能这样做。尝试：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1044544|Queue<Integer>+Q+=+new+LinkedList<Integer>();|code-block|syntax|javascript|1044545|entityMap^0|0|5|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

<code>Queue</code> is an interface in java, you could not do that.
try:

<pre><code>Queue&lt;Integer&gt; Q = new LinkedList&lt;Integer&gt;();
</code></pre>

When I try:
<pre><code>Queue&lt;Integer&gt; q = new Queue&lt;Integer&gt;();
</code></pre>
The compiler is giving me an error. Any help?
Also, if I want to initialize a queue do I have to implement the methods of the queue?

How do I instantiate a Queue object in java?

编译器

当我尝试的时候：Queue<Integer> q = new Queue<Integer>();编译器给了我一个错误。有什么帮助吗？另外，如果我想初始化一个队列，我必须实现队列的方法吗？

问如何在java中实例化队列对象？
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回答 6

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