如何守护Java项目中的线程

//完成文件输出的守护线程任务import java.io.*; class TestRunnable implements Runnable{   public void run(){         try{          Thread.sleep(1000);//守护线程阻塞1秒后运行          File f=new File("daemon.txt");          FileOutputStream os=new FileOutputStream(f,true);          os.write("daemon".getBytes());       }         catch(IOException e1){      e1.printStackTrace();         }         catch(InterruptedException e2){          e2.printStackTrace();       }   } } public class TestDemo2{   public static void main(String[] args) throws InterruptedException   {     Runnable tr=new TestRunnable();     Thread thread=new Thread(tr);         thread.setDaemon(true); //设置守护线程     thread.start(); //开始执行分进程   } }