java - 如果线程自身调用 join() 会发生什么

Question

从我在这里读到的Thread join on itself ;

当 join 方法被调用时，它应该永远等待

我目前正在准备 ocajp 8 认证，为此经历了转储，当我得到这个问题时，我认为主要的应该永远等待

     public class startinginconstructor extends Thread
    {
        private int x=2;
        startinginconstructor()
        {   
            start();
        }
        public static void main(String[] args) throws Exception
        {
        new startinginconstructor().makeitso(); 
        }
        public void makeitso() throws Exception
        {
            x=x-1;
            System.out.println(Thread.currentThread().getName()+" about to call join ");
            join();
            System.out.println(Thread.currentThread().getName()+" makeitso completed "); 

           //  above line shouldn't be executed (method shouldn't be completed as well )since it joined on itself..?

        }
        public void run()
        {
    System.out.println(Thread.currentThread().getName()+" run started ");
        x*=2;
    System.out.println(Thread.currentThread().getName()+" run about to complete ");  
        }
    }

程序以下列输出结束

main about to call join
Thread-0 run started
Thread-0 run about to complete
main makeitso completed

我是不是错误地理解了线程永远等待的含义，还是我遗漏了什么

note: I know starting thread from constructor is not a recommended practice.. this is exact question in the dumps so i just pasted it (* not pretty much exact actually,i have placed println statements to see flow of the program)

Answer 1

在您的示例中没有加入自身的线程。

示例中的 main() 线程创建了一个新线程，然后它加入了新线程。

不要将 Thread(即 java 对象)与 thread(代码的执行)混淆。您的所有方法都属于同一个 Thread 对象，但它们在两个不同的线程中运行。