Getting Screen width and height in android studio

I am using this code to get my screen width and height and send my button to a random position on the screen but sometimes my button is completely off-screen. I don't believe that the resolution my code gets me is the true res. Any help would be appreciated.

        DisplayMetrics displayMetrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
    float height = displayMetrics.heightPixels;
    float width = displayMetrics.widthPixels;

    float maxX = width;
    float maxY = height;
    float minX = width/10;
    float minY = height/15;

    Random rand = new Random();

    float finalX = rand.nextFloat() * abs(maxX - minX);
    float finalY = rand.nextFloat() * abs(maxY - minY);

    _height.setText("Current Y: " + String.valueOf(finalY));
    _width.setText("Current X: " + String.valueOf(finalX));
    max_height.setText("Max height: " + String.valueOf(height));
    max_width.setText("Max width: " + String.valueOf(width));
    btnClick.setX(finalX);
    btnClick.setY(finalY);
    btnClick.setVisibility(View.VISIBLE);

Here are 2 pictures displaying my problem. Button slightly on-screen Button completely off-screen