java中两种有趣的匿名种实现

java中两种有趣的匿名类实现

java中的匿名类除了还有两种有趣的用法

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/** * TODO Comment of AnonymousTest *  * @author aotian.zhuw */class EntryInterface {    public void print() {        System.out.println("hello world");    }}public class AnonymousTest {    private EntryInterface a;    public void setA(EntryInterface a) {        this.a = a;    }    public void print() {        a.print();    }    public static void main(String[] args) {        AnonymousTest test = new AnonymousTest();        test.setA(new EntryInterface() {            public void print() {                System.out.println("test success.");            }        });        test.print();    }}

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首先看上面的代码我们在setA中传入的是一个匿名类

编译之后得到三个文件EntryInterface.class?AnonymousTest.class ?AnonymousTest$1.class

反编译AnonymousTest$1.class文件，得到的结果如下

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package cn.zw;import java.io.PrintStream;// Referenced classes of package cn.zw://            EntryInterface, AnonymousTeststatic class AnonymousTest$1 extends EntryInterface{    public void print()    {        System.out.println("test success.");    }    AnonymousTest$1()    {    }}

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结果我们发现，java的编译器自动创建了一个EntryInterface的子类，

名为AnonymousTest$1,且该类覆盖了父类的print()方法。

修改AnonymousTest类

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interface EntryInterface {    public void print();}public class AnonymousTest {    private EntryInterface a;    public void setA(EntryInterface a) {        this.a = a;    }    public void print() {        a.print();    }    public static void main(String[] args) {        AnonymousTest test = new AnonymousTest();        test.setA(new EntryInterface() {            public void print() {                System.out.println("test success.");            }        });        test.print();    }}

??编译之后仍旧得到三个文件EntryInterface.class?AnonymousTest.class ?AnonymousTest$1.class

?反编译AnonymousTest$1.class文件，得到的结果如下

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import java.io.PrintStream;// Referenced classes of package cn.zw://            EntryInterface, AnonymousTeststatic class AnonymousTest$1    implements EntryInterface{    public void print()    {        System.out.println("test success.");    }    AnonymousTest$1()    {    }}

?这次我们发现编译器创建的AnonymousTest$1类实现了EntryInterface接口，很有趣。