How to create Android Device Network Listener based on on/off network?

This example demonstrates how do I create Android Device Network Listener based on on/off network.

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:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   android:padding="16sp"
   tools:context=".MainActivity">
<TextView
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="30dp"
   android:text="Android Device Network Listener based on on/off network"
   android:textSize="24sp"
   android:textStyle="bold" />
<Button
   android:layout_marginTop="30dp"
   android:onClick="SwitchWIFION"
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:text="Switch on Wifi"/>
<Button
   android:layout_marginTop="10dp"
   android:onClick="SwitchWIFIOFF"
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:text="Switch on Wifi"/<
</LinearLayout>

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

import androidx.appcompat.app.AppCompatActivity;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
import java.util.Objects;
public class MainActivity extends AppCompatActivity {
   WifiManager wifiManager;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      wifiManager = (WifiManager) getApplicationContext().getSystemService(WIFI_SERVICE);
      ConnectivityManager connectivityManager = (ConnectivityManager)
      getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
      NetworkInfo activeNetInfo =
      Objects.requireNonNull(connectivityManager).getActiveNetworkInfo();
      NetworkInfo mobNetInfo =
      connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
      if (activeNetInfo != null) {
         Toast.makeText(getApplicationContext(), "Active Network Type : " +
         activeNetInfo.getTypeName(), Toast.LENGTH_SHORT).show();
      }
      if (mobNetInfo != null) {
         Toast.makeText(getApplicationContext(), "Mobile Network Type : " +
         mobNetInfo.getTypeName(), Toast.LENGTH_SHORT).show();
      }
   }
   public void SwitchWIFION(View view) {
      Objects.requireNonNull(wifiManager).setWifiEnabled(true);
      Toast.makeText(getApplicationContext(), "WIFI SWITCHED ON",
      Toast.LENGTH_SHORT).show();
   }
   public void SwitchWIFIOFF(View view) {
      Objects.requireNonNull(wifiManager).setWifiEnabled(false);
      Toast.makeText(getApplicationContext(), "WIFI SWITCHED OFF",
      Toast.LENGTH_SHORT).show();
   }
}

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.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">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
   <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
</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 the 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 −