The problem

android.graphics.Rect.intersect(Rect r) and android.graphics.Rect.intersect(int, int, int, int) do not always modify the rectangle to the intersected result. If the rectangles do not intersect, no change is made and the original rectangle is not modified. These methods return false to indicate that this has happened.

If you don’t check the return value of these methods, you may end up drawing the wrong rectangle.

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("RectIntersectReturnValueIgnored") to the enclosing element.