SOS flashlight - How to

Question

I made a flashlight app and now I want to add sos morse code flashing. This is my code for it but it doesen't work quite well, it blinks too fast so I need some kind of a delay, can anyone help?

public void sos(View v) {
    String myString = "111000111";
    Handler handler = new Handler();


    for (int x = 0; x < myString.length(); x++) {
        if (myString.charAt(x) == '1') {
            handler.postDelayed(new Runnable() {
                public void run() {
                    params.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
                    camera.setParameters(params);
                    camera.startPreview();
                }
            }, 300);


            handler.postDelayed(new Runnable() {
                public void run() {
                    params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
                    camera.setParameters(params);
                 }
            }, 300);


            handler.postDelayed(new Runnable() {
                public void run() {
                    params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
                    camera.setParameters(params);
                }
            }, 300);

        }

    }
}

If I understand what the problem is, then each Handler is running after 300 milliseconds. There is not a 300 millisecond delay between each one. If you want to do that, then you need to start another thread at the end of another one — OneCricketeer, Oct 12 '16 at 20:09
can you do it for me? I just started learning this so I'm not really able to do that — Domagoj Lipušić, Oct 12 '16 at 20:11
You could also use `Thread.sleep()`, but that will halt the app's main thread — OneCricketeer, Oct 12 '16 at 20:13
Why are you using handler.postDelayed? I would try somehting simpler like Thread.sleep() — GC_, Oct 12 '16 at 20:17

score 1 · Accepted Answer · answered Oct 12 '16 at 20:20

1

Note: I am not an app programmer, but here is a sample of Thread.sleep(). Good luck.

 for (int x = 0; x < myString.length(); x++) {
    if (myString.charAt(x) == '1') {                
          params.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
          camera.setParameters(params);
          camera.startPreview();
    }     
    Thread.sleep(300);      


    params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
    camera.setParameters(params);


}

answered Oct 12 '16 at 20:20

GC_

448
4
23

This will likely crash the app as sleeping the main thread is bad, but it's as good a start as any. See http://stackoverflow.com/a/3039718/2308683 – OneCricketeer Oct 12 '16 at 20:31

score 0 · Answer 2 · answered Oct 12 '16 at 21:27

Second take on it. Assuming it is true you can't sleep the main thread, try this:

int delay=0;
for (int x = 0; x < myString.length(); x++) {
    if (myString.charAt(x) == '1') {
        handler.postDelayed(new Runnable() {
                public void run() {
                    params.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
                    camera.setParameters(params);
                    camera.startPreview();
                }
            }, (delay+=300));


        handler.postDelayed(new Runnable() {
                public void run() {
                    params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
                    camera.setParameters(params);
                 }
            }, (delay+=300));




        }

    }

SOS flashlight - How to

2 Answers2