Ask for overlay permission in API 23 or above

example.java

public class MainActivity extends SplashActivity {

    public static int ACTION_MANAGE_OVERLAY_PERMISSION_REQUEST_CODE = 5469;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        checkPermission();
    }

    @TargetApi(Build.VERSION_CODES.M)
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == ACTION_MANAGE_OVERLAY_PERMISSION_REQUEST_CODE) {
            if (!Settings.canDrawOverlays(this)) {
                // We don't have permission, ask for permission.
                checkPermission();
            }
        }

    }

    public void checkPermission() {
        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:" + getPackageName()));
                startActivityForResult(intent, ACTION_MANAGE_OVERLAY_PERMISSION_REQUEST_CODE);
            }
        }
    }

}