通常通过继承某个类或实现某个接口的方式来编写代码，但是有时候某一些代码只使用一次，就没有必要写专门写一个子类或实现类了，可以采用匿名内部类的写法。最常用的场景是线程方面的应用。

一、不使用匿名内部类

①继承 abstract class Player {  public abstract void play(); }

public class FootBallPlayer extends Player

{  public void play()  {   System.out.println("踢足球");  } }

public class AnonymousInnerClassTest

{  public static void main(String[] args)  {   Player p1 = new FootBallPlayer();   p1.play();  } }

②接口

interface IPlayer {  public void play(); }

public class IPlayFootballImpl implements IPlayer

{  public void play()  {   System.out.println("踢足球");  } }

public class AnonymousInnerClassTest

{  public static void main(String[] args)  {      IPlayer ip1 = new IPlayFootballImpl();   ip1.play();  } }

二、使用匿名内部类

①继承 abstract class Player {  public abstract void play(); }

public class AnonymousInnerClassTest

{  public static void main(String[] args)  {   Player p2 = new Player() {    public void play()    {     System.out.println("打篮球");    }   };   p2.play();  } }

②接口

interface IPlayer {  public void play(); }

public class AnonymousInnerClassTest

{  public static void main(String[] args)  {      IPlayer ip2 = new IPlayer() {    public void play()    {     System.out.println("打篮球");    }   };  } }

三、线程中的应用

实现线程的方法有两种：①继承Thread类 ②实现Runnable接口。给出用匿名类实现的例子：

public class ThreadTest

{  public static void main(String[] args)  {   // 继承Thread类   Thread thread = new Thread() {    @Override    public void run()    {     while (true)     {      try      {       Thread.sleep(1000);       System.out.println(Thread.currentThread().getName());       System.out.println(this.getName());      }      catch (InterruptedException e)      {       System.out.println(e.getMessage());      }     }    }   };   thread.start();

  // 实现Runnable接口

  Thread thread2 = new Thread(new Runnable() {    @Override    public void run()    {     while (true)     {      try      {       Thread.sleep(1000);       System.out.println(Thread.currentThread().getName());      }      catch (InterruptedException e)      {       System.out.println(e.getMessage());      }     }    }   });   thread2.start();  } }