Sync.java

class Callme {
  void call(String message) {
    try {
      Thread.sleep(1000);
    } catch(InterruptedException e) {
      System.out.println("Interrupted. Message is " + message);
    }

    System.out.print("[" + message);
    System.out.println("]");
  }
}

class Caller implements Runnable {
  Thread t;
  private String message;
  private Callme target;

  Caller(Callme target, String message) {
    this.target = target;
    this.message = message;

    t = new Thread(this);
    t.start();
  }

  Caller(Callme target, String message, int priority) {
    this.target = target;
    this.message = message;

    t = new Thread(this);
    t.setPriority(priority);
    System.out.println(t.getPriority());
    t.start();
  }

  public void run() {
    target.call(message);
  }
}

class Sync {
  public static void main(String args[]) {
    Callme target = new Callme();
    Caller ob1 = new Caller(target, "Hello", 1);
    Caller ob2 = new Caller(target, "Synchronized", 2);
    Caller ob3 = new Caller(target, "World", 3);

    try {
      ob1.t.join();
      ob2.t.join();
      ob3.t.join();
    } catch(InterruptedException e) {
      System.out.println("Interrupted");
    }
  }
}

// 输出：
// localhost:java angelawang$ java Sync
// 1
// 2
// 3
// [World[Synchronized]
// [Hello]
// ]
// localhost:java angelawang$ java Sync
// 1
// 2
// 3
// [Hello[World]
// [Synchronized]
// ]
// localhost:java angelawang$ java Sync
// 1
// 2
// 3
// [Synchronized[World]
// [Hello]
// ]