Have three TextViews with Red, Green and Blue in your activity set onClick listener for all of them and in onClick:
int currentColor=Color.RED;
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.red:
currentColor=Color.RED;
break;
case R.id.green:
currentColor=Color.GREEN;
break;
case R.id.blue:
currentColor=Color.BLUE;
break;
default:
break;
}
}