button_for_contacts.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item>

        <shape
            android:shape="rectangle">
            <corners
                android:bottomLeftRadius = "20dp"
                android:topLeftRadius = "20dp"
                android:topRightRadius = "20dp"
                android:bottomRightRadius ="20dp"
                android:radius = "10dp"/>
            <solid
                android:color = "#000000" />
        </shape>
    </item>

</selector>