Positioning widgets added to layout using addView

I want to position the stopButton to top-right. It shows on top-left. How do I achieve that?

Here's the code:

private WindowManager wm;
private WindowManager.LayoutParams params1;
LinearLayout layout;
Button stopButton;
TextView text;

@Override
public void onCreate() {
    super.onCreate();
    /**getWindow().addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED);
     getWindow().addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);**/
    text = (TextView) findViewById(R.id.texttest);
    layout = new LinearLayout(this);
    stopButton = new Button(this);
    ViewGroup.LayoutParams buttonParams = new ViewGroup.LayoutParams(
            ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
    stopButton.setBackgroundDrawable(getResources().getDrawable(R.drawable.cancel));
    stopButton.setLayoutParams(buttonParams);
    layout.addView(stopButton);

    LinearLayout.LayoutParams mLinearLayout = new LinearLayout.LayoutParams(
            LinearLayout.LayoutParams.MATCH_PARENT,
            LinearLayout.LayoutParams.MATCH_PARENT);
    layout.setBackgroundColor(Color.argb(66, 255, 0, 0));
    layout.setLayoutParams(mLinearLayout);
    wm = (WindowManager) this.getSystemService(Context.WINDOW_SERVICE);
    params1 = new WindowManager.LayoutParams(
            200, 150, WindowManager.LayoutParams.TYPE_SYSTEM_ALERT |
            WindowManager.LayoutParams.TYPE_PHONE,
            WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL |
                    WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
            PixelFormat.TRANSPARENT);

    params1.x = 0;
    params1.y = 0;
    params1.gravity = Gravity.CENTER | Gravity.TOP;
    params1.format = PixelFormat.TRANSPARENT;
    wm.addView(layout, params1);

Also, I'm using this in a Service class. Is it possible that I write all of elements I want to add to LinearLayout (for example, stopButton) within XML? If I can do that, how do I add it to the LinearLayout?