java - 使线程在 Java 中以特定顺序启动

Question

我想制作一个简单的线程程序，只需使用 sleep() 方法即可按 1、2、3 的顺序启动 3 个线程，然后按 3、2、1 的顺序停止。但是，每次线程都以不同的顺序启动。

class Thread1 extends Thread{   
  public void run(){        
     System.out.println("Thread 1 running...");
     try {
        this.sleep(5000);
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
     System.out.println("Thread 1 has terminated");
  }
} 

class Thread2 extends Thread {
  public void run(){
     System.out.println("Thread 2 running...");
     try {
        this.sleep(2000);
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
     System.out.println("Thread 2 has terminated");
  }
}

class Thread3 extends Thread {
  public void run(){
     System.out.println("Thread 3 running...");
     try {
        this.sleep(1000);
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
     System.out.println("Thread 3 has terminated");
  }
}

public static void main(String[] args) throws InterruptedException {     
    Thread tr1 = new Thread1();
    Thread tr2 = new Thread2();
    Thread tr3 = new Thread3();
    tr1.start();
    tr2.start();
    tr3.start();        
}

当前输出:

Thread 1 running...
Thread 3 running...
Thread 2 running...
Thread 3 has terminated
Thread 2 has terminated
Thread 1 has terminated

期望的输出:

Thread 1 running...
Thread 2 running...
Thread 3 running...
Thread 3 has terminated
Thread 2 has terminated
Thread 1 has terminated

Answer 1

您的线程以正确的顺序启动，但输出可能是错误的，因为输出消息是同时到达的。您应该将消息传送到主线程中:

public static void main(String[] args) throws InterruptedException {     
    Thread tr1 = new Thread1();
    Thread tr2 = new Thread2();
    Thread tr3 = new Thread3();
    tr1.start();
    System.out.println("Thread 1 started");
    tr2.start();
    System.out.println("Thread 2 started");
    tr3.start();      
    System.out.println("Thread 3 started");  
}