Subscript and Superscript a String in Android using Kotlin

This example demonstrates how to Subscript and Superscript a String in Android using Kotlin

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:padding="8dp"
   tools:context=".MainActivity">
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="50dp"
      android:text="Tutorials Point"
      android:textAlignment="center"
      android:textColor="@android:color/holo_green_dark"
      android:textSize="32sp"
      android:textStyle="bold" />
   <TextView
      android:id="@+id/textView"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:fontFamily="sans-serif-condensed"
      android:textAlignment="center"
      android:textColor="@android:color/background_dark"
      android:textSize="36sp"
      android:textStyle="bold" />
</RelativeLayout>

Step 3 − Add the following code to src/MainActivity.kt

import android.os.Bundle
import android.text.SpannableStringBuilder
import android.text.Spanned
import android.text.style.RelativeSizeSpan
import android.text.style.SubscriptSpan
import android.text.style.SuperscriptSpan
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
   lateinit var textView: TextView
   private lateinit var strText: String
   lateinit var spannableStringBuilder: SpannableStringBuilder
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      textView = findViewById(R.id.textView)
      strText = "Test text to show SubscriptSpan X2 and SuperscriptSpan Y5 example."
      spannableStringBuilder = SpannableStringBuilder(strText)
      val subscriptSpan = SubscriptSpan()
      val superscriptSpan = SuperscriptSpan()
      spannableStringBuilder.setSpan(subscriptSpan, strText.indexOf("2"),
      strText.indexOf("2") + "2".length,
      Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
      spannableStringBuilder.setSpan(superscriptSpan, strText.indexOf("5"), strText.indexOf("5") +
      "5".length,
      Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
      showSmallSizeText("2")
      showSmallSizeText("5")
      textView.text = spannableStringBuilder
   }
   private fun showSmallSizeText(string: String) {
      val relativeSizeSpan = RelativeSizeSpan(.5f)
      spannableStringBuilder.setSpan(relativeSizeSpan, strText.indexOf(string),
      strText.indexOf(string) + string.length, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
   }
}

Step 4 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="app.com.q11">
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click the Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen