how to Underline the selected radio button in android?

I have radio buttons. I want when the selected radio button to be underlined.

<RadioGroup
            android:weightSum="3"
            android:orientation="horizontal"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <RadioButton
                android:padding="20dp"
                android:layout_weight="1"
                android:text="Collections"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:button="@null"
                android:background="@drawable/radio_button_background"/>

            <RadioButton

                android:layout_weight="1"
                android:text="Inspections"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:button="@null"
                android:background="@drawable/radio_button_background"/>

            <RadioButton
                android:layout_weight="1"
                android:text="Enforcements"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:button="@null"
                android:background="@drawable/radio_button_background"/>

        </RadioGroup>

here is the radio_button_background background I have created.

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_checked="true">
        <shape android:shape="line">
            <stroke
                android:width="4dp"
                android:color="#0000FF"
                android:gravity="bottom"
                android:dashWidth="0dp"
                android:dashGap="1000dp"/>
        </shape>
    </item>
    <item>
        <shape android:shape="line">
            <solid android:color="@android:color/transparent"/>
        </shape>
    </item>
</selector>

I want when I select the radio button, the active one is underlined. like below image

1. Give ids to your radion group and radio buttons

   <RadioGroup
        android:id="@+id/radio_group"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:weightSum="3">
   
        <RadioButton
            android:id="@+id/rb_collections"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@drawable/te"
            android:button="@null"
            android:text="Collections"
            android:textAlignment="center" />
   
        <RadioButton
            android:id="@+id/rb_inspections"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:button="@null"
            android:text="Inspections"
            android:textAlignment="center" />
   
        <RadioButton
            android:id="@+id/rb_enforcements"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:button="@null"
            android:text="Enforcements"
            android:textAlignment="center" />
   </RadioGroup>
   

2. Create a background with the bottom line that you need for selected button

   <?xml version="1.0" encoding="utf-8"?>
   <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:left="-40dp"
        android:right="-40dp"
        android:top="-40dp">
        <shape android:shape="rectangle">
            <stroke
                android:width="2dp"
                android:color="@android:color/holo_blue_dark" />
        </shape>
    </item>
   </layer-list>
   

3. When ever the state of radio group changes, you set the background to selected radio button

   val rb = findViewById<RadioGroup>(R.id.radio_group)
   val rbCollections = findViewById<RadioButton>(R.id.rb_collections)
   val rbInspections = findViewById<RadioButton>(R.id.rb_inspections)
   val rbEnforcements = findViewById<RadioButton>(R.id.rb_enforcements)
   rb.setOnCheckedChangeListener { group, checkedId ->
        // remove background of every button 
        rbCollections.setBackgroundResource(0)
        rbInspections.setBackgroundResource(0)
        rbEnforcements.setBackgroundResource(0)
   
        // set background of button which is checked
        when(checkedId){
            R.id.rb_collections -> rbCollections.setBackgroundResource(R.drawable.bg)
            R.id.rb_inspections -> rbInspections.setBackgroundResource(R.drawable.bg)
            R.id.rb_enforcements -> rbEnforcements.setBackgroundResource(R.drawable.bg)
        }
   }