Java中的匿名内部类

忘是亡心i 2021-09-25 15:46 383阅读 0赞

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();  
\}  
\}