Use this drawable to generate a border with round corners

border-round-corner.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="@null" />
    <stroke
        android:width="1dp"
        android:color="@color/colorPrimary" />
    <padding
        android:bottom="1dp"
        android:left="1dp"
        android:right="1dp"
        android:top="1dp" />
    <corners android:radius="8dp" />
</shape>