javaschedule参数_Java之Timer的schedule方法period参数分析

下面为一段标准的Timer用法private void runTimer(){

Log.d("bloguan", "run:" &＃43; Thread.currentThread().getId());

new Timer().schedule(new TimerTask() {

&＃64;Override

public void run() {

Log.d("bloguan", "begin:" &＃43; Thread.currentThread().getId());

Log.d("bloguan", "end:" &＃43; Thread.currentThread().getId());

}

},1000, 5000);

}

执行结果11-06 11:25:04.105 2385-2385/com.bloguan.demo D/bloguan: run:1

11-06 11:25:05.106 2385-2410/com.bloguan.demo D/bloguan: begin:139

11-06 11:25:05.106 2385-2410/com.bloguan.demo D/bloguan: end:139

11-06 11:25:10.108 2385-2410/com.bloguan.demo D/bloguan: begin:139

11-06 11:25:10.108 2385-2410/com.bloguan.demo D/bloguan: end:139

分析&＃xff1a;Timer延时1秒执行&＃xff0c;每5秒循环一次&＃xff0c;TimerTask的run运行在子线程

那么&＃xff0c;有个疑问&＃xff0c;如果run里面执行耗时操作&＃xff0c;每5秒的循环周期还准吗&＃xff1f;

试一下&＃xff0c;我们在run中加一个2秒“耗时操作”private void runTimer(){

Log.d("bloguan", "run:" &＃43; Thread.currentThread().getId());

new Timer().schedule(new TimerTask() {

&＃64;Override

public void run() {

Log.d("bloguan", "begin:" &＃43; Thread.currentThread().getId());

try {

Thread.sleep(2000);

} catch (InterruptedException e) {

e.printStackTrace();

}

Log.d("bloguan", "end:" &＃43; Thread.currentThread().getId());

}

},1000, 5000);

}

执行结果11-06 11:30:27.947 2496-2496/com.bloguan.demo D/bloguan: run:1

11-06 11:30:28.948 2496-2514/com.bloguan.demo D/bloguan: begin:143

11-06 11:30:30.956 2496-2514/com.bloguan.demo D/bloguan: end:143

11-06 11:30:33.949 2496-2514/com.bloguan.demo D/bloguan: begin:143

11-06 11:30:35.949 2496-2514/com.bloguan.demo D/bloguan: end:143

11-06 11:30:38.951 2496-2514/com.bloguan.demo D/bloguan: begin:143

11-06 11:30:40.952 2496-2514/com.bloguan.demo D/bloguan: end:143

分析&＃xff1a;定时器仍然每5秒触发一次&＃xff0c;run里面的2秒耗时操作不会叠加到5秒这个周期上

如果耗时操作大于period这个周期呢&＃xff1f;

把上面代码中的sleep改为6秒Thread.sleep(6000);

执行结果11-06 11:43:22.544 2586-2586/com.bloguan.demo D/bloguan: run:1

11-06 11:43:23.546 2586-2604/com.bloguan.demo D/bloguan: begin:147

11-06 11:43:29.546 2586-2604/com.bloguan.demo D/bloguan: end:147

11-06 11:43:29.546 2586-2604/com.bloguan.demo D/bloguan: begin:147

11-06 11:43:35.593 2586-2604/com.bloguan.demo D/bloguan: end:147

11-06 11:43:35.593 2586-2604/com.bloguan.demo D/bloguan: begin:147

分析&＃xff1a;Timer的周期先到&＃xff0c;但run没执行完&＃xff0c;会等到执行完成后再次循环

结论&＃xff1a;

1、TimerTask的run运行在子线程&＃xff0c;非UI线程

2、如果TimerTask的run中有耗时操作

当耗时操作小于period周期时&＃xff0c;仍以period时间为准进行周期循环

当耗时操作大于period周期时&＃xff0c;等run执行完后&＃xff0c;立即进行下一次