How to I connect to wifi network on Android programmatically?

This example demonstrates how do I connect wifi network in Android programatically.
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
   android:id="@+id/activity_main"
   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"
   tools:context="MainActivity">
   <Switch
      android:id="@+id/switchWifi"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_centerVertical="true" />
   <TextView
      android:id="@+id/textView"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_above="@+id/switchWifi"
      android:layout_centerHorizontal="true"
      android:layout_marginBottom="42dp"
      android:text="WiFi OFF"
      android:textAppearance="?android:attr/textAppearanceLarge" />
</RelativeLayout>
Step 3 − Add the following code to src/MainActivity.java
import android.content.Context;
import android.net.wifi.WifiManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.CompoundButton;
import android.widget.Switch;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
   Switch WiFiButton;
   TextView textview;
   WifiManager wifiManager;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      textview = findViewById(R.id.textView);
      WiFiButton = findViewById(R.id.switchWifi);
      WiFiButton.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
         @Override
         public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            // TODO Auto-generated method stub
            if(isChecked) {
               textview.setText("WII ON");
               EnableWiFi() ;
            } else {
               textview.setText("WII OFF");
               DisableWiFi();
            }
         }
      });
   }
   public void EnableWiFi(){
      wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
      wifiManager.setWifiEnabled(true);
   }
   public void DisableWiFi(){
      wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
      wifiManager.setWifiEnabled(false);
   }
}
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">
   <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
   <uses-permission android:name="android.permission.INTERNET" />
   <uses-permission android:name="android.permission.CHANGE_WIFI_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.