<?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="16dp"
 tools:context=".MainActivity">
 <TextView
   android:id="@+id/textView"
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:layout_centerInParent="true"
   android:textAlignment="center"
   android:textSize="24sp"
   android:textStyle="bold" />
</RelativeLayout>

import androidx.appcompat.app.AppCompatActivity;
import android.os.Build;
import android.os.Bundle;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
 TextView textView;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);
   textView = findViewById(R.id.textView);
   double release = Double.parseDouble(Build.VERSION.RELEASE.replaceAll("(\\d+[.]\\d+)(.*)","$1"));
   String codeName ="Unsupported";
   if (release >= 4.1 && release < 4.4) codeName ="Jelly Bean";
   else if (release < 5) codeName ="Kit Kat";
   else if (release < 6) codeName ="Lollipop";
   else if (release < 7) codeName ="Marshmallow";
   else if (release < 8) codeName ="Nougat";
   else if (release < 9) codeName ="Oreo";
   textView.setText(codeName +" Version" + release +", API LEVEL:" + Build.VERSION.SDK_INT);
 }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="app.com.sample">
 <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">
   
    <intent-filter>
     
      <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
   </activity>
 </application>
</manifest>