private final static int REQUEST_CODE = 101;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_overlay);

        ButterKnife.bind(this);


        checkDrawOverlayPermission();
    }

    private void checkDrawOverlayPermission() {

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (!Settings.canDrawOverlays(this)) {

                Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION, Uri.parse("package:" + this.getPackageName()));

                startActivityForResult(intent, REQUEST_CODE);
                finish();
            }
        }
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (resultCode == REQUEST_CODE) {

            Toast.makeText(this, "Ok", Toast.LENGTH_SHORT).show();

            Intent intent = new Intent(getApplicationContext(), MainActivity.class);
            startActivity(intent);
        }
    }