It’s actually fairly easy to set the underline color of an EditText programmatically (just one line of code).
To set the color:
editText.getBackground().setColorFilter(color, PorterDuff.Mode.SRC_IN);
To remove the color:
editText.getBackground().clearColorFilter();
Note: when the EditText has focus on, the color you set won’t take effect, instead, it has a focus color.
API Reference: