浅谈java线程join方法使用方法

public class ThreadTest {
  //private static final Long count = 10000L;
  public static void main(String[] args){
    long base = System.currentTimeMillis();
    try {
      ThreadJoin t1 = new ThreadJoin("线程1");
      ThreadJoin t2 = new ThreadJoin("线程2");
      //t1.join();
      t1.start();
      t1.join();
      t2.start();

    } catch (Exception e) {
      e.printStackTrace();
    }
    long time = System.currentTimeMillis() - base;
    System.out.println("执行时间："+time);
  }
  
}
class ThreadJoin extends Thread{
  private static final Long count = 10L;

  public ThreadJoin(String name){
    super(name);
  }

  @Override
  public void run() {
    //super.run();
    for(int i = 1; i <= count; i ++){
      System.out.println(this.getName()+":"+i);
    }
  }
}

public class ThreadTest {
  //private static final Long count = 10000L;
  public static void main(String[] args){
    long base = System.currentTimeMillis();
    try {
      ThreadJoin t1 = new ThreadJoin("线程1");
      ThreadJoin t2 = new ThreadJoin("线程2");
      //t1.join();
      t1.start();
      t1.join();
      t2.start();

    } catch (Exception e) {
      e.printStackTrace();
    }
    long time = System.currentTimeMillis() - base;
    System.out.println("执行时间："+time);
  }
  
}
class ThreadJoin extends Thread{
  private static final Long count = 10L;

  public ThreadJoin(String name){
    super(name);
  }

  @Override
  public void run() {
    //super.run();
    for(int i = 1; i <= count; i ++){
      System.out.println(this.getName()+":"+i);
    }
  }
}

/**
   * Waits for this thread to die.
   *
   * <p> An invocation of this method behaves in exactly the same
   * way as the invocation
   *
   * <blockquote>
   * {@linkplain #join(long) join}{@code (0)}
   * </blockquote>
   *
   * @throws InterruptedException
   *     if any thread has interrupted the current thread. The
   *     <i>interrupted status</i> of the current thread is
   *     cleared when this exception is thrown.
   */
  public final void join() throws InterruptedException {
    join(0);
  }

public final synchronized void join(long millis)
  throws InterruptedException {
    long base = System.currentTimeMillis();
    long now = 0;
 //执行时间必须为正数
    if (millis < 0) {
      throw new IllegalArgumentException("timeout value is negative");
    }
 //执行时间为0或者缺省情况
    if (millis == 0) {
      while (isAlive()) {//表示线程还没执行好
        wait(0);//调用线程的wait方法
      }
    } else {//执行时间大于0的情况
      while (isAlive()) {
        long delay = millis - now;//循环计算延期时间
        if (delay <= 0) {
          break;
        }
        wait(delay);//同样调用线程的wait方法
        now = System.currentTimeMillis() - base;
      }
    }
  }