Radio buttons are used when we want to choose only one item from the list of items.
android: orientation: Can be horizontal or vertical
setOnCheckedChangeListener (): It records a callback to be called when the radio button is checked changed in this group.
and following the example of syntax applied to the layout (xml).
<RadioButton
android:id="@+id/radioButton1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Radio Button 1 "
android:textSize="18sp"/>Source: Master Android (App)
