Java Timer timer

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Timer

1. Overview timer

• Timer, you can set the thread execution at a time something or a certain time, every specified time interval repeatedly to do something;

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2. Timer class

• Timer class can implement thread scheduling tasks for the future and is performed in the background thread, you can schedule a task to perform, or repeated periodically;
• java.util.Timer,详见: Class Hours ;

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3. Constructor

Construction method	Explanation
Timer()	Constructs a timer

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4. Members method

return value	Method name	Explanation
void	schedule(TimerTask task, long delay)	Schedule tasks specified execution after a specified delay
void	schedule(TimerTask task, long delay, long period)	Start after a specified delay, re-execute the tasks specified fixed delay execution
void	schedule(TimerTask task, Date time)	Schedules the specified task execution at a specified time
void	schedule(TimerTask task, Date firstTime, long period)	Starting at the specified time, to perform the specified task for repeated fixed-delay execution

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5. Java Examples

import java.text.SimpleDateFormat;
import java.util.*;

public class Test {
    public static void main(String[] args) {
        //1.设置一个定时器，2秒后启动，只执行一次
        Timer t = new Timer();
        t.schedule(new TimerTask() {
            @Override
            public void run() {
                for (int i = 10; i >= 0; i--) {
                    System.out.println("倒数：" + i);
                    try {
                        Thread.sleep(1000);
                    } catch (Exception e) {
                    }
                }
                System.out.println("嘭......嘭......");
                //任务执行完毕，终止计时器
                t.cancel();
            }
        }, 2000);

        //2.设置一个定时器，5秒后开始执行，每一秒执行一次
        Timer t2 = new Timer();
        t2.schedule(new TimerTask() {
            @Override
            public void run() {
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                System.out.println(sdf.format(new Date()));
            }
        }, 5000, 1000);

        //3.设置一个定时器，在2030年01月01日零时开始执行，每隔24小时执行一次
        Timer t3 = new Timer();
        Calendar c = new GregorianCalendar(2030, 1 - 1, 1, 0, 0, 0);
        Date d = c.getTime();

        t3.schedule(new TimerTask() {
            @Override
            public void run() {
                System.out.println("搜索全盘......");
            }
        }, d, 1000 * 3600 * 24);
    }
}
/*
部分输出
倒数：10
倒数：9
倒数：8
倒数：7
2020-03-08 20:50:12
2020-03-08 20:50:13
倒数：6
2020-03-08 20:50:14
倒数：5
2020-03-08 20:50:15
倒数：4
2020-03-08 20:50:16
倒数：3
2020-03-08 20:50:17
倒数：2
2020-03-08 20:50:18
倒数：1
2020-03-08 20:50:19
倒数：0
2020-03-08 20:50:20
嘭......嘭......
2020-03-08 20:50:21
2020-03-08 20:50:22
...
 */