How to underline text in textview

 <?xml version="1.0" encoding="utf-8"?>
 <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity3">

    <androidx.appcompat.widget.AppCompatTextView
        android:id="@+id/txtcandidrootsolution"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Welcome To Candidroot Solutions"
        android:textSize="20sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
 </androidx.constraintlayout.widget.ConstraintLayout>

 import android.annotation.SuppressLint
 import android.os.Bundle
 import android.text.SpannableString
 import android.text.style.UnderlineSpan
 import android.widget.TextView
 import androidx.appcompat.app.AppCompatActivity

 class MainActivity3 : AppCompatActivity() {
    @SuppressLint("MissingInflatedId")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main4)
        val mTextView = findViewById<TextView>(R.id.txtcandidrootsolution)
        val mString = "Welcome To Candidroot Solutions"
        val mSpannableString = SpannableString(mString)
        mSpannableString.setSpan(UnderlineSpan(), 0, mSpannableString.length, 0)
        mTextView.text = mSpannableString
    }
 }