两种方式循环检测条件变化handler和sleep

 1.使用handler循环往外抛消息检测

    public void startDetect(long initialDelay, long period){
            Handler handler = new Handler(Looper.getMainLooper());
            runnable = new Runnable() {
                @Override
                public void run() {
                    if(满足条件) {
                        doTask();
                        return;
                    }
                    handler.postDelayed(runnable, 100);
                }
            };
            handler.post(runnable);
        }

2.java中的方法，一个死循环，然后使用sleep隔一段时间检测一下

public class sleepTask {

    static volatile Boolean isInterrupt = false;

    public static void main(String[] args) {

        TimerTask task = new TimerTask() {
            @Override
            public void run() {
                isInterrupt = true;
            }
        };
        Timer timer = new Timer();
        timer.schedule(task, 1000);

        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                while (true) {
                    if (isInterrupt) {
                        System.out.println("execute task");
                        Thread.currentThread().interrupt();
                        return;
                    } else {
                        try {
                            Thread.sleep(250);
                            System.out.println("waitting ...");
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        };

        Thread thread = new Thread(runnable);
        thread.start();
    }
}