How to hook into the Power button in Android?

Question

On an Android device, where the only buttons are the volume buttons and a power button, I want to make the app react to presses on the power button (long and short). How is

Answer 1

Sharing a method to listen for Power button long press. Works with API 23+ permissions:

1. Asking for system permission to draw overlay (This is not a normal or vulnerable permission). This is not a user permission, so You should really know, what you are doing, by asking for it.

   public class MainActivity extends AppCompatActivity {
   
       public final static int REQUEST_CODE = 10101;
   
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
           if (checkDrawOverlayPermission()) {
               startService(new Intent(this, PowerButtonService.class));
           }
       }
   
       public boolean checkDrawOverlayPermission() {
           if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
               return true;
           }
           if (!Settings.canDrawOverlays(this)) {
               /** if not construct intent to request permission */
               Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION,
                   Uri.parse("package:" + getPackageName()));
           /** request permission via start activity for result */
               startActivityForResult(intent, REQUEST_CODE);
               return false;
           } else {
               return true;
           }
       }
   
       @Override
       @TargetApi(Build.VERSION_CODES.M)
       protected void onActivityResult(int requestCode, int resultCode, Intent data) {
           if (requestCode == REQUEST_CODE) {
               if (Settings.canDrawOverlays(this)) {
                   startService(new Intent(this, PowerButtonService.class));
               }
           }
       }
   }
   

2. Starting a service and adds a special view to WindowManager

3. Waiting for an action inside View's onCloseSystemDialogs method.

   public class PowerButtonService extends Service {
   
       public PowerButtonService() {
   
       }
   
       @Override
       public void onCreate() {
           super.onCreate();
           LinearLayout mLinear = new LinearLayout(getApplicationContext()) {
   
               //home or recent button
               public void onCloseSystemDialogs(String reason) {
                   if ("globalactions".equals(reason)) {
                       Log.i("Key", "Long press on power button");
                   } else if ("homekey".equals(reason)) {
                       //home key pressed
                   } else if ("recentapss".equals(reason)) {
                       // recent apps button clicked
                   }
               }
   
               @Override
               public boolean dispatchKeyEvent(KeyEvent event) {
                   if (event.getKeyCode() == KeyEvent.KEYCODE_BACK
                       || event.getKeyCode() == KeyEvent.KEYCODE_VOLUME_UP
                       || event.getKeyCode() == KeyEvent.KEYCODE_VOLUME_DOWN
                       || event.getKeyCode() == KeyEvent.KEYCODE_CAMERA
                       || event.getKeyCode() == KeyEvent.KEYCODE_POWER) {
                       Log.i("Key", "keycode " + event.getKeyCode());
                   }
                   return super.dispatchKeyEvent(event);
               }
           };
   
           mLinear.setFocusable(true);
   
           View mView = LayoutInflater.from(this).inflate(R.layout.service_layout, mLinear);
           WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);
   
           //params
           WindowManager.LayoutParams params = new WindowManager.LayoutParams(
               100,
               100,
               WindowManager.LayoutParams.TYPE_SYSTEM_ALERT,
               WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
                       | WindowManager.LayoutParams.FLAG_FULLSCREEN
                       | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN
                       | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON,
               PixelFormat.TRANSLUCENT);
           params.gravity = Gravity.LEFT | Gravity.CENTER_VERTICAL;
           wm.addView(mView, params);
       }
   
       @Override
       public IBinder onBind(Intent intent) {
           return null;
       }
   }
   

Manifest:

service_layout: