How to get programmatically android version number?

This example demonstrates How to get programmatically android version number.
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"?>
<LinearLayout 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:layout_width = "match_parent"
   android:gravity = "center"
   android:layout_height = "match_parent"
   tools:context = ".MainActivity">
   <TextView
      android:id = "@+id/text"
      android:textSize = "30sp"
      android:layout_width = "match_parent"
      android:layout_height = "match_parent" />
</LinearLayout>
In the above code, we have taken text view to show device version number.
Step 3 − Add the following code to src/MainActivity.java
package com.example.myapplication;
import android.Manifest;
import android.app.ProgressDialog;
import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.RequiresApi;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.webkit.CookieManager;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
   TextView textView;
   @RequiresApi(api = Build.VERSION_CODES.P)
   @Override
   protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      textView = findViewById(R.id.text);
      if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_PHONE_STATE) != PackageManager.PERMISSION_GRANTED) {
         ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_PHONE_STATE}, 101);
      }
   }
   @RequiresApi(api = Build.VERSION_CODES.O)
   @Override
   public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
      switch (requestCode) {
         case 101:
         if (grantResults[0] = = PackageManager.PERMISSION_GRANTED) {
            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_PHONE_STATE) != PackageManager.PERMISSION_GRANTED) {
               return;
            }
            textView.setText(""+Build.VERSION.SDK_INT);
         } else {
            //not granted
         }
         break;
         default:
         super.onRequestPermissionsResult(requestCode, permissions, grantResults);
      }
   }
   @RequiresApi(api = Build.VERSION_CODES.O)
   @Override
   protected void onResume() {
      super.onResume();
      if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_PHONE_STATE) != PackageManager.PERMISSION_GRANTED) {
         return;
      }
      textView.setText(""+Build.VERSION.SDK_INT);
   }
}
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 = "com.example.myapplication">
   <uses-permission android:name = "android.permission.INTERNET"/>
   <uses-permission android:name = "android.permission.READ_PHONE_STATE" />
   <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 Run  icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen –
Click here to download the project code