public class OutClass{ //外部类

        class InnerClass{...}//内部类 

     public static void main(String[] args){ 

        InnerClass in = new OutClass().new InnerClass();//定义内部类成员变量 

} 

}

public class ThreadTest{

        
        public static void main(String[] args) {
                Thread t=new Thread(new ThreadTest().new Print());
                t.start();
                
        }
        
        class Print implements Runnable{
                @Override
                public void run() {
                        while(true){
                        try {
                                Thread.sleep(1000);
                                System.out.println("haha");
                        } catch (InterruptedException e) {
                                // TODO Auto-generated catch block
                                e.printStackTrace();
                        }
                        }
                        
                }
        }
        

}