<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:color="#ffff0000" android:state_pressed="true"/>
    <item android:color="#ff0000ff" android:state_focused="true"/>
    <item android:color="#ff000000" />
</selector>

<Button
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="Click"
    android:textColor="@color/btn"/>