blocks|key|742872|text|在代码中，您没有创建接口的实例。相反，代码定义了一个实现接口的匿名类，并实例化该类。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|742873|该守则大致相当于：|742874|public+final+class+Document+{

++++private+final+class+AnonymousContentVisitor+implements+ContentVisitor+{

++++++++public+void+onStartDocument()+{
++++++++++++throw+new+IllegalStateException();
++++++++}

++++++++public+void+onEndDocument()+{
++++++++++++out.endDocument();
++++++++}

++++++++public+void+onEndTag()+{
++++++++++++out.endTag();
++++++++++++inscopeNamespace.popContext();
++++++++++++activeNamespaces+=+null;
++++++++}
++++}

++++private+final+ContentVisitor+visitor+=+new+AnonymousContentVisitor();
}|code-block|syntax|javascript|742875|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

In the code, you're not creating an instance of the interface. Rather, the code defines an anonymous class that implements the interface, and instantiates that class.

The code is roughly equivalent to:

<pre><code>public final class Document {

 private final class AnonymousContentVisitor implements ContentVisitor {

 public void onStartDocument() {
 throw new IllegalStateException();
 }

 public void onEndDocument() {
 out.endDocument();
 }

 public void onEndTag() {
 out.endTag();
 inscopeNamespace.popContext();
 activeNamespaces = null;
 }
 }

 private final ContentVisitor visitor = new AnonymousContentVisitor();
}
</code></pre>

blocks|key|362846|text|它称为anonymous类型/类，它实现了该接口。看看教程-+本地和匿名内部类。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|362847|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/tutorial/java/javaOO/innerclasses.html^0|3|9|V|8|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@$9|Q|A|R|1|S]]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

It is called <code>anonymous</code> type/class which implements that interface. Take a look at tutorial - <a href="http://docs.oracle.com/javase/tutorial/java/javaOO/innerclasses.html" rel="nofollow">Local and Anonymous Inner Classes</a>.

blocks|key|362858|text|该声明实际上创建了一个新的匿名类，该类实现了ContentVisitor接口，然后实现了该给定作用域的实例，并且非常有效。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|362859|entityMap^0|M|E|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

That declaration actually creates a new anonymous class which implements the <code>ContentVisitor</code> interface and then its instance for that given scope and is perfectly valid.

blocks|key|362875|text|在java+http://www.java2s.com/Code/Java/Class/Anonymous-class.htm中有一种叫做匿名类的东西|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|362876|entityMap|0|LINK|mutability|MUTABLE|url|http://www.java2s.com/Code/Java/Class/Anonymous-class.htm^0|6|1L|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

There's something called anonymous class in java <a href="http://www.java2s.com/Code/Java/Class/Anonymous-class.htm" rel="nofollow">http://www.java2s.com/Code/Java/Class/Anonymous-class.htm</a>

blocks|key|362883|text|请注意大括号打开的位置--您正在声明一个实现ContentVisitor和所有必需方法的内部对象(称为ContentVisitor)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|362884|entityMap^0|M|E|1F|E|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

Do notice where the braces open - you are declaring an inner object (called <code>anonymous class</code>) that implements <code>ContentVisitor</code> and all required methods on the spot!

blocks|key|262722|text|它是内联接口implementation.Here，其思想是让编译器生成一个实现接口的匿名类。然后，对于接口中定义的每个方法，您可以(可选)提供一个具有合适签名的方法，该签名将用作接口方法的实现。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|262723|这是一种新的Oxygene语法，添加到语言中，允许Oxygene程序员以与Java程序员一样的方式处理这些基于接口的事件。|262724|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

It is inline interface implementation.Here the idea is to have the compiler generate an anonymous class that implements the interface. Then for each method defined in the interface you can (optionally) provide a method with a suitable signature that will be used as the implementation of the interface's method.

It is the new Oxygene syntax, added to the language to allow Oxygene programmers to work with these interface-based events in much the same way as Java programmers do.

blocks|key|743151|text|是有效的。这叫匿名课。看这里|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|743152|我们已经看到了定义和实例化匿名类的语法示例。我们可以更正式地将这种语法表述为：
新类名(参数列表){类体}
或者：
新接口-name+()+{类-body}|blockquote|743153|entityMap|0|LINK|mutability|MUTABLE|url|http://docstore.mik.ua/orelly/java-ent/jnut/ch03_12.htm^0|B|3|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@$A|P|B|Q|1|R]]|C|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|C|$]]|$1|G|3|-4|5|6|7|T|8|@]|9|@]|C|$]]]|H|$I|$5|J|K|L|C|$M|N]]]]

It's valid. It's called Anonymous class. <a href="http://docstore.mik.ua/orelly/java-ent/jnut/ch03_12.htm">See here</a>

<blockquote>
 We've already seen examples of the syntax for defining and instantiating an anonymous class. We can express that syntax more formally as:

<pre><code>new class-name ( [ argument-list ] ) { class-body }
</code></pre>
 
 or:

<pre><code>new interface-name () { class-body }
</code></pre>
</blockquote>

blocks|key|262815|text|实际上，您已经以匿名的方式提供了这个接口的实现。这是相当普遍的，当然也是可能的。有关更多信息，请查看这里。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|262816|entityMap|0|LINK|mutability|MUTABLE|url|http://docstore.mik.ua/orelly/java-ent/jnut/ch03_12.htm^0|1E|2|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

You actually have just provided the implementation of this interface in an anonymous way. This is quite common and of course possible. Have a look <a href="http://docstore.mik.ua/orelly/java-ent/jnut/ch03_12.htm" rel="nofollow">here</a> for more information.

blocks|key|262854|text|由于问题仍然存在，Java+8引入了lambda。我必须提一提。Lambda与AIC相比有几个优点。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|262855|可读性/引入函数式编程。|unordered-list-item|262856|在一些案例性能中。|offset|length|262857|但lambda和AIC的范围不同。您不能创建Lambda实例并获得对lambda本身的引用。|262858|entityMap|0|LINK|mutability|MUTABLE|url|http://youtu.be/6UX8ChrIMrM^0|0|0|3|2|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$]]|$1|E|3|F|5|D|7|U|8|@]|9|@$G|V|H|W|1|X]]|A|$]]|$1|I|3|J|5|6|7|Y|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

Since the question is still actual and Java 8 brought in lambda. I must mention it. Lambda comparing with AIC has a couple of advantages.
<ul>
<li>readability / introduce functional programming.</li>
<li>in some <a href="http://youtu.be/6UX8ChrIMrM" rel="nofollow noreferrer">cases</a> performance.</li>
</ul>
But lambda and AIC have different scope. You can't create an instance of Lambda and obtain a reference to lambda itself.

I was reading some sourcecode from Java libraries, and I am confused here;

This code is from Document.java in jaxb library, and ContentVisitor is an Interface in same package, how can we create an instance of Interface with a new keyword? isn't that illegal?

<pre><code>public final class Document {
.
.
 private final ContentVisitor visitor = new ContentVisitor() {
 public void onStartDocument() {

 throw new IllegalStateException();
 }

 public void onEndDocument() {
 out.endDocument();
 }

 public void onEndTag() {
 out.endTag();
 inscopeNamespace.popContext();
 activeNamespaces = null;
 }
}
</code></pre>

Java: Interface with new keyword how is that possible?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在阅读Java库中的一些源代码，在这里我感到很困惑；这段代码来自jaxb库中的Document.java，而ContentVisitor是同一个包中的接口，我们如何使用新关键字创建接口实例？这不违法吗？public final class Document {.. private final ContentVisi...

问Java:使用新关键字的接口怎么可能？
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