Java的守护线程

我会带着你远行 2021-09-29 12:50 331阅读 0赞

**一 点睛**

针对守护线程，只要有一个用户线程在执行，这个进程就不会结束。

当线程中只剩下守护线程时，JVM会自动退出，反之，如果还有其他任何用户线程存在，JVM都不会退出。

**二 代码**

public class ThreadDaemon
    {
       public static void main( String args[] )
       {
          ThreadTest t = new ThreadTest();
          Thread tt = new Thread( t );
          tt.setDaemon( true ); // 设置后台运行
          tt.start( );
          try
          {  // 睡眠1毫秒，避免可能出现的没有输出的现象
             Thread.sleep( 1 );
          }
          catch( InterruptedException e )
          {
             e.printStackTrace();
          }
       }
    }
    
    class ThreadTest implements Runnable
    {
       public void run()
       {
          for( int i = 0; true; ++i )
          {
             System.out.println( i + "  " + Thread.currentThread().getName()
                   + " is running." );
          }
       }
    }

**三 运行**

0  Thread-0 is running.
    1  Thread-0 is running.
    2  Thread-0 is running.
    3  Thread-0 is running.
    4  Thread-0 is running.
    5  Thread-0 is running.
    6  Thread-0 is running.
    7  Thread-0 is running.
    8  Thread-0 is running.
    9  Thread-0 is running.
    10  Thread-0 is running.
    11  Thread-0 is running.
    12  Thread-0 is running.
    13  Thread-0 is running.
    14  Thread-0 is running.
    15  Thread-0 is running.
    16  Thread-0 is running.
    17  Thread-0 is running.
    18  Thread-0 is running.
    19  Thread-0 is running.
    20  Thread-0 is running.
    21  Thread-0 is running.
    22  Thread-0 is running.
    23  Thread-0 is running.
    24  Thread-0 is running.
    25  Thread-0 is running.
    26  Thread-0 is running.
    27  Thread-0 is running.
    28  Thread-0 is running.