一定时间后如何关闭窗口/活动

Question

am writing an android application, it allow someone add two numbers and input the answer. but I want this numbers to display for only 5 seconds and then a new number show up, if they input the correct or wrong answer, the timer reset and display new numbers.. i have written the code that does the random numbers and other just the timer am unable to do someone help please

Answer 1

Using a Handler and Runnable should work for you but don't use an Anonymous runnable as they can cause memory leaks. Instead extend runnable into a static class and use removeCallbacks in onDestroy .

Also you can use WeakReference as onDestroy is not guaranteed to be called so a WeakReference will allow GC to free up the memory if your activity gets killed

public class BarActivity extends AppCompatActivity {

    private Handler mHandler;
    private FooRunnable mRunnable;

    private void finishActivityAfterDelay(int milliSeconds) {
        mHandler = new Handler();
        mRunnable = new FooRunnable(this);
        mHandler.postDelayed(mRunnable, 5000); // 5 seconds
    }

    @Override
    protected void onDestroy() {
        mHandler.removeCallbacks(mRunnable);
        super.onDestroy();
    }

    private static class FooRunnable implements Runnable {
        private WeakReference<AppCompatActivity> mWeakActivity;

        public FooRunnable(AppCompatActivity activity) {
            mWeakActivity = new WeakReference<>(activity);
        }

        @Override
        public void run() {
            AppCompatActivity activity = mWeakActivity.get();
            if (activity != null) activity.finish();
        }

    }

}

Answer 2

You can use android.os.Handler class to do so, Like

private Handler handler = new Handler(); // Create Handler

Runnable runnable = new Runnable() {
     @Override
     public void run() {
         // Perform action here...
     }           
};
handler.postDelayed(runnable, 3 * 1000); // action will be performed after 3 seconds.

Answer 3

 CountDownTimer timer = new CountDownTimer(30000/*modify value as per need*/, 1000) {

     public void onTick(long millisUntilFinished) {
        //millisUntilFinised is the remaining time
     }

     public void onFinish() {
        //timer finished .Do what you need to do next here
     }
  };

use timer.start(); where you had to start the timer.