I have the following code where I want to listen to Volume down key press and do something in the same as in the constraintLayout onClickListener:

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        supportActionBar?.hide();
        textureView = findViewById(R.id.view_finder);
        constraintLayout = findViewById<ConstraintLayout>(R.id.screen)
        imgCap = findViewById<ImageView>(R.id.imgCapture)

        if (allPermissionsGranted()) {
            Log.i("PermissionsGranted", "Starting Camera...")
            startCamera()
        } else {
            ActivityCompat.requestPermissions(this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS);
        }
    }
    private fun startCamera() {
         constraintLayout.setOnClickListener { _: View? -> 
              // do something
         }
    
        // do the same thing as ClickListener above if volume down key is pressed
    }

I have tried to hack this by overriding onKeyDown but haven't figured out a solution.

CodePudding user response：

Try this:

@Override
public boolean dispatchKeyEvent(KeyEvent event) {
    int keyCode = event.getKeyCode();
    switch (keyCode) {
        case KeyEvent.KEYCODE_VOLUME_UP:
            //Volume up
            
            return true;
        case KeyEvent.KEYCODE_VOLUME_DOWN:
            //Volume down
            
            return true;
        default:
            return super.dispatchKeyEvent(event);
    }
}

And if you want to do the same what on click you can do:

constraintLayout.performClick();