打印100怎么办？

Question

我想在下面的程序中打印100作为输出.

我得到0作为答案.

    class s extends Thread{
    int j=0; 
        public void run() { 
            try{Thread.sleep(5000);} 
            catch(Exception e){} 
            j=100; 
        } 
        public static void main(String args[]) 
        { 
            s t1=new s(); 
            t1.start(); 
            System.out.println(t1.j); 
        } 

}

Answer 1

你需要等待Thread到finish..I添加一个电话加入你,这将阻止和等待Thread,以观察前值完成j:

class s extends Thread{
    int j=0; 
    public void run() { 
        try{ Thread.sleep(5000); } catch( Exception e ){} 
        j = 100; 
    } 

    public static void main(String args[]) throws InterruptedException { 
        s t1=new s(); 
        t1.start(); 
        t1.join() ; // Wait for t1 to finish
        System.out.println(t1.j); 
    } 
}

Answer 2

你加入了t1到main.因此,父级thread(main())将等待子线程完成.