This document provides instructions on how to use the WifiManager in Android to control WiFi settings and scan for available networks. It explains how to get the WifiManager instance, start a scan, register a broadcast receiver to detect when scanning is complete, and retrieve the list of scanned networks. It also demonstrates how to check and change the active WiFi state. The code examples show implementing these features to build a simple app with buttons to scan and enable/disable WiFi and display the results.

1. Develop on Android
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Lesson : The Wifi manager

2. The Wifi manager
• In this lesson, you will learn to use the Wifi manager.
• For this, you will use the Wifi manager WifiManager.

3. The Wifi manager
• Use getSystemService() to access to the Wifi manager.
WifiManager wifiManager = (WifiManager)getSystemService(Context.WIFI_SERVICE);
• To start the scan of networks, call the method startScan().
wifiManager.startScan();
• To control the status active or inactive, use the methods isWifiEnabled() and
setWifiEnabled().
if (wifiManager.isWifiEnabled()) {
wifiManager.setWifiEnabled(false);
} else {
wifiManager.setWifiEnabled(true);
}

4. The Wifi manager
• To get notified when the search is finished, register a BroadcastReceiver.
Receiver receiver = new Receiver();
registerReceiver(receiver,new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
registerReceiver(receiver,new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));

5. The Wifi manager
• This receiver receives the status in the action
(SCAN_RESULTS_AVAILABLE_ACTION). Then the SSIDs can be rad with the
method getScanResults() of the WifiManager.
public class Receiver extends BroadcastReceiver {
public void onReceive(Context context, Intent intent) {
if(intent.getAction().equals(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)){
List<ScanResult> results = wifiManager.getScanResults();
for(int i=0;i<results.size();i++){
String ssid = results.get(i).SSID;
}
}
}
}

6. Layout main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button
android:id="@+id/btnScan"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Scan" />
<Button
android:id="@+id/btnActivate"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Activate / disactivate" />
<EditText
android:id="@+id/et_status"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10" />

7. Layout main.xml
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="SSID" />
<EditText
android:id="@+id/et_ssid"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:ems="10" />
</LinearLayout>

8. File Main.java
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button btnScan = (Button)findViewById (R.id.btnScan);
btnScan.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
wifiManager.startScan();
}
});
Button btnEnable = (Button)this.findViewById(R.id.btnActivate);
btnEnable.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
if(wifiManager.isWifiEnabled()) {
wifiManager.setWifiEnabled(false);
et_ssid.setText("Disabled");
} else {
wifiManager.setWifiEnabled(true);
et_ssid.setText("Enabled");
}
}
});

9. File Main.java
et_ssid = (TextView)findViewById (R.id.et_ssid);
et_status = (TextView)findViewById (R.id.et_status);
wifiManager = (WifiManager)getSystemService(Context.WIFI_SERVICE);
Receiver receiver = new Receiver();
registerReceiver(receiver,new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
registerReceiver(receiver,new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
}
public class Receiver extends BroadcastReceiver {
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals (WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)) {
List<ScanResult> results = wifiManager.getScanResults();
String ssid = "";
for (int i = 0; i < results.size(); i++) {
ssid += results.get(i).SSID + ", ";
}
et_ssid.setText(ssid);
}
}
}
}

10. Project AndroidManifest.xml
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>
<uses-permission android:name="android.permission.WAKE_LOCK"/>

11. Test on your mobile
System_Wifi

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