Java中的匿名内部类

2021-09-25 03:41:15

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();
}
}

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