多线程编程<四>

 1 /**
 2  * 守护线程daemon['diːmən]
 3  * @author Administrator
 4  *
 5  */
 6 public class DaemonDemo {
 7     public static void main(String[] args) {
 8         MyDaemon dt = new MyDaemon();
 9
10         if (dt.thrd.isDaemon()) {
11             System.out.println("dt is a daemon thread.");
12         }
13         System.out.println("Sleeping in main thread.");
14         try{
15             Thread.sleep(10000);
16         }
17         catch(InterruptedException exc){
18             System.out.println("Main thread interrupted.");
19         }
20
21         System.out.println("\nMain thread ending.");
22     }
23 }
24
25 class MyDaemon implements Runnable{
26     Thread thrd;
27
28     public MyDaemon() {
29         thrd = new Thread(this);
30         thrd.setDaemon(true);//守护线程：当用户线程结束时，守护线程也结束。
31         thrd.start();
32     }
33
34     @Override
35     public void run() {
36
37         try {
38             for(;;) {
39                 System.out.print(".");
40                 Thread.sleep(1000);
41             }
42         } catch (InterruptedException e) {
43             System.out.println("MyDaemon interrupted.");
44         }
45     }
46 }

一个简单的Reminder

 1 import java.util.Calendar;
 2 import java.util.GregorianCalendar;
 3
 4
 5 public class ReminderDemo {
 6     public static void main(String[] args) {
 7         Reminder mt = new Reminder("Call Harry", 2);
 8
 9         Reminder mt2 = new Reminder("Meet with Bill", new GregorianCalendar(2014,4,14,21,14));
10
11         for(int i = 0; i < 20; i++){
12             try {
13                 Thread.sleep(1000);
14             } catch (InterruptedException e) {
15                 System.out.println("Main thread interrupted.");
16             }
17             System.out.print(".");
18         }
19         System.out.println("\nMain thread ending.");
20     }
21 }
22 class Reminder implements Runnable {
23
24     Calendar reminderTime;
25
26     String message;
27
28     public Reminder(String msg, int delay) {
29         message = msg;
30         reminderTime = Calendar.getInstance();
31         reminderTime.add(Calendar.SECOND, delay);
32         System.out.printf("Reminder set for %tD %1$tr\n", reminderTime);
33         Thread dThrd = new Thread(this);
34         dThrd.setDaemon(true);
35         dThrd.start();
36     }
37
38     public Reminder(String msg, Calendar cal) {
39         message = msg;
40
41         reminderTime = cal;
42         System.out.printf("Reminder set for %tD %1$tr\n", reminderTime);//变元索引
43         Thread dThrd = new Thread(this);
44         dThrd.setDaemon(true);
45         dThrd.start();
46     }
47     @Override
48     public void run() {
49         try {
50             for(;;){
51                 Calendar curTime = Calendar.getInstance();
52                 if(curTime.compareTo(reminderTime) >= 0) {
53                     System.out.println("\n" + message + "\n");
54                     break;
55                 }
56                 Thread.sleep(1000);
57             }
58         } catch (InterruptedException e) {
59             System.out.println("Reminder interrupted.");
60         }
61     }
62
63 }