java 线程方法join简单用法实例总结

public class JoinTest {
  public static void main(String [] args) throws InterruptedException {
    ThreadJoinTest t1 = new ThreadJoinTest("小明");
    ThreadJoinTest t2 = new ThreadJoinTest("小东");
    t1.start();
    /**join的意思是使得放弃当前线程的执行，并返回对应的线程，例如下面代码的意思就是：
     程序在main线程中调用t1线程的join方法，则main线程放弃cpu控制权，并返回t1线程继续执行直到线程t1执行完毕
     所以结果是t1线程执行完后，才到主线程执行，相当于在main线程中同步t1线程，t1执行完了，main线程才有执行的机会
     */
    t1.join();
    t2.start();
  }
}
class ThreadJoinTest extends Thread{
  public ThreadJoinTest(String name){
    super(name);
  }
  @Override
  public void run(){
    for(int i=0;i<1000;i++){
      System.out.println(this.getName() + ":" + i);
    }
  }
}

public class JoinTest {
  public static void main(String [] args) throws InterruptedException {
    ThreadJoinTest t1 = new ThreadJoinTest("小明");
    ThreadJoinTest t2 = new ThreadJoinTest("小东");
    t1.start();
    /**join方法可以传递参数，join(10)表示main线程会等待t1线程10毫秒，10毫秒过去后，
     * main线程和t1线程之间执行顺序由串行执行变为普通的并行执行
     */
    t1.join(10);
    t2.start();
  }
}
class ThreadJoinTest extends Thread{
  public ThreadJoinTest(String name){
    super(name);
  }
  @Override
  public void run(){
    for(int i=0;i<1000;i++){
      System.out.println(this.getName() + ":" + i);
    }
  }
}

public class JoinTest {
  public static void main(String [] args) throws InterruptedException {
    ThreadJoinTest t1 = new ThreadJoinTest("小明");
    ThreadJoinTest t2 = new ThreadJoinTest("小东");
    /**join方法可以在start方法前调用时，并不能起到同步的作用
     */
    t1.join();
    t1.start();
    //Thread.yield();
    t2.start();
  }
}
class ThreadJoinTest extends Thread{
  public ThreadJoinTest(String name){
    super(name);
  }
  @Override
  public void run(){
    for(int i=0;i<1000;i++){
      System.out.println(this.getName() + ":" + i);
    }
  }
}

public final synchronized void join(long millis)
  throws InterruptedException {
    long base = System.currentTimeMillis();
    long now = 0;
    if (millis < 0) {
      throw new IllegalArgumentException("timeout value is negative");
    }

    if (millis == 0) {
      while (isAlive()) {
        wait(0);
      }
    } else {
      while (isAlive()) {
        long delay = millis - now;
        if (delay <= 0) {
          break;
        }
        wait(delay);
        now = System.currentTimeMillis() - base;
      }
    }
  }