Java线程编程中isAlive()和join()的使用详解

  final boolean isAlive( )

  final void join( ) throws InterruptedException

// Using join() to wait for threads to finish.class NewThread implements Runnable {  String name; // name of thread  Thread t;  NewThread(String threadname) {    name = threadname;    t = new Thread(this, name);    System.out.println("New thread: " + t);    t.start(); // Start the thread  }  // This is the entry point for thread.  public void run() {    try {      for(int i = 5; i > 0; i--) {        System.out.println(name + ": " + i);        Thread.sleep(1000);      }    } catch (InterruptedException e) {      System.out.println(name + " interrupted.");    }    System.out.println(name + " exiting.");  }}class DemoJoin {  public static void main(String args[]) {    NewThread ob1 = new NewThread("One");    NewThread ob2 = new NewThread("Two");    NewThread ob3 = new NewThread("Three");    System.out.println("Thread One is alive: "+ ob1.t.isAlive());    System.out.println("Thread Two is alive: "+ ob2.t.isAlive());    System.out.println("Thread Three is alive: "+ ob3.t.isAlive());    // wait for threads to finish    try {      System.out.println("Waiting for threads to finish.");      ob1.t.join();      ob2.t.join();      ob3.t.join();    } catch (InterruptedException e) {      System.out.println("Main thread Interrupted");    }    System.out.println("Thread One is alive: "+ ob1.t.isAlive());    System.out.println("Thread Two is alive: "+ ob2.t.isAlive());    System.out.println("Thread Three is alive: "+ ob3.t.isAlive());    System.out.println("Main thread exiting.");  }}

New thread: Thread[One,5,main]New thread: Thread[Two,5,main]New thread: Thread[Three,5,main]Thread One is alive: trueThread Two is alive: trueThread Three is alive: trueWaiting for threads to finish.One: 5Two: 5Three: 5One: 4Two: 4Three: 4One: 3Two: 3Three: 3One: 2Two: 2Three: 2One: 1Two: 1Three: 1Two exiting.Three exiting.One exiting.Thread One is alive: falseThread Two is alive: falseThread Three is alive: falseMain thread exiting.