Android change color of shape Instance

Question

I have three buttons with same ripple shape.

when I enter activity I change color of single buttons shape.

RippleDrawable bg = (RippleDrawable) button.getBackground(); GradientDrawable gradient = (GradientDrawable) bg.findDrawableByLayerId(R.id.ripple_color); gradient.setColor(Color.Black);

but when I reenter activity all buttons have this new color. How to change only this instance of shape instead of modifying shape itself

Answer 1

From the Drawable documentation:

By default, all drawables instances loaded from the same resource share a common state; if you modify the state of one instance, all the other instances will receive the same modification.

So your problem is here:

GradientDrawable gradient = (GradientDrawable) bg.findDrawableByLayerId(R.id.ripple_color);
gradient.setColor(Color.Black);

To avoid the issue mentioned in the documentation, simply call mutate() on the drawable before changing its state.

GradientDrawable gradient =
        (GradientDrawable) bg.findDrawableByLayerId(R.id.ripple_color).mutate();
gradient.setColor(Color.Black);