AutoSizeOfGroupTextView

activity.kt

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.os.Handler
import android.util.TypedValue
import android.widget.TextView
import androidx.core.widget.TextViewCompat
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        setSimilarSize(listOf(
            text1,
            text2,
            text3
        ))

    }

    private fun setSimilarSize(list: List<TextView>) {
        val maxLengthIndex = getMaxLengthIndex(list)

        list[maxLengthIndex].post {
            val textSize = list[maxLengthIndex].textSize.toInt()
            for (item in list){
                TextViewCompat.setAutoSizeTextTypeUniformWithConfiguration(
                    item,
                    textSize,
                    textSize+1,
                    1,
                    TypedValue.COMPLEX_UNIT_DIP
                )
            }
        }

    }

    private fun getMaxLengthIndex(list: List<TextView>): Int {
        var maxLength = list[0].length()
        var maxIndex = 0
        for ((i, item) in list.withIndex()){
            if (item.length() >= maxLength){
                maxLength = item.length()
                maxIndex = i
            }
        }
        return maxIndex
    }
}

activity.xml

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

    <LinearLayout
            android:orientation="horizontal"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            android:gravity="center">
        <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="20000000000000000000!"
                app:autoSizeMaxTextSize="18dp"
                app:autoSizeMinTextSize="6dp"
                app:autoSizeStepGranularity="1dp"
                app:autoSizeTextType="uniform"
                android:gravity="center"
                android:lines="1"
                android:id="@+id/text1"
                android:layout_weight="1"/>
        <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="55555555!"
                app:autoSizeMaxTextSize="18dp"
                app:autoSizeMinTextSize="6dp"
                app:autoSizeStepGranularity="1dp"
                app:autoSizeTextType="uniform"
                android:lines="1"
                android:gravity="center"
                android:id="@+id/text2"
                android:visibility="gone"
                android:layout_weight="1"/>
        <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="9999999999!!!"
                app:autoSizeMaxTextSize="18dp"
                app:autoSizeMinTextSize="6dp"
                app:autoSizeStepGranularity="1dp"
                app:autoSizeTextType="uniform"
                android:lines="1"
                android:gravity="center"
                android:layout_weight="1" android:id="@+id/text3"/>
    </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>