Android: Change the Alpha value of button.

To set the Alpha value

Drawable d = getResources().getDrawable(R.drawable.Imagename);
d.setAlpha(50);
buttonId.setBackgroundDrawable(d);

You can set alpha level 0 to 255

o means transparent and 255 means opaque.

to restore the Original button.

Drawable d = getResources().getDrawable(R.drawable.Imagename);

d.setAlpha(255);

buttonId.setBackgroundDrawable(d);