Java 다중 스레드에서 join 방법에 대한 사용 실례 분석

코드 먼저 올리기
새 Thread 코드는 다음과 같습니다.

package com.thread.test;
public class MyThread extends Thread {
  private String name;
  public MyThread(String name) {
    this.name = name;
  }
  @Override
  public void run() {
    for (int i = 0; i < 100; i++) {
      System.out.println(name+"["+i+"]");
    }
    super.run();
  }
}

다음에 새 테스트 클래스를 만듭니다. 코드는 다음과 같습니다.

package com.thread.test;
/*
 * 0-50 ,50-100 A , A 
 */
public class ThreadDemo{
  public static void main(String[] args) {
    MyThread t = new MyThread("A");
    t.start();
    for (int i = 0; i < 100; i++) {
      if (i>50) {
        try {
          t.join();
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }
      System.out.println(" "+"["+i+"]");
    }
  }
}

다음은 Java Platform SE8 API에서 Thread의 Join 방법에 대한 설명입니다.

public final void join(long millis)
        throws InterruptedExceptionWaits at most millis milliseconds for this thread to die. A timeout of 0 means to wait forever. 
This implementation uses a loop of this.wait calls conditioned on this.isAlive. As a thread terminates the this.notifyAll method is invoked. It is recommended that applications not use wait, notify, or notifyAll on Thread instances.
Parameters: 
millis - the time to wait in milliseconds 
Throws: 
IllegalArgumentException - if the value of millis is negative 
InterruptedException - if any thread has interrupted the current thread. The interrupted status of the current thread is cleared when this exception is thrown.

코드 먼저 올리기
새 Thread 코드는 다음과 같습니다.

package com.thread.test;
public class MyThread extends Thread {
  private String name;
  public MyThread(String name) {
    this.name = name;
  }
  @Override
  public void run() {
    for (int i = 0; i < 100; i++) {
      System.out.println(name+"["+i+"]");
    }
    super.run();
  }
}

다음에 새 테스트 클래스를 만듭니다. 코드는 다음과 같습니다.

package com.thread.test;
/*
 * 0-50 ,50-100 A , A 
 */
public class ThreadDemo{
  public static void main(String[] args) {
    MyThread t = new MyThread("A");
    t.start();
    for (int i = 0; i < 100; i++) {
      if (i>50) {
        try {
          t.join();
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }
      System.out.println(" "+"["+i+"]");
    }
  }
}

다음은 Java Platform SE8 API에서 Thread의 Join 방법에 대한 설명입니다.

public final void join(long millis)
        throws InterruptedExceptionWaits at most millis milliseconds for this thread to die. A timeout of 0 means to wait forever. 
This implementation uses a loop of this.wait calls conditioned on this.isAlive. As a thread terminates the this.notifyAll method is invoked. It is recommended that applications not use wait, notify, or notifyAll on Thread instances.
Parameters: 
millis - the time to wait in milliseconds 
Throws: 
IllegalArgumentException - if the value of millis is negative 
InterruptedException - if any thread has interrupted the current thread. The interrupted status of the current thread is cleared when this exception is thrown.

내 자신의 이해는 Join 방법을 사용하는 라인에 강제로 들어갈 것이고, 다른 라인은 이 라인이 완전히 실행된 후에야 들어올 것이다.