Develop Reference

Broadcast action for WIFI change

In my application I have to get notified whenever the device connects or disconnects from a WIFI network. For this I have to use a BroadcastReceiver but after reading through different articles and questions here on SO I'm a bit confused which Broadcast action I should use for this. In my opinion I have three choices:
SUPPLICANT_CONNECTION_CHANGE_ACTION
NETWORK_STATE_CHANGED_ACTION
CONNECTIVITY_ACTION
To reduce resources I really only want to get notified whenever the device is CONNECTED to a WIFI network (and it has received an IP address) or when the device has DISCONNECTED from one. I do not care about the other states like CONNECTING etc.
So what do you think is the best Broadcast action I should use for this? And do I have to manully filter the events (because I receieve more then CONNECTED and DISCONNECTED) in onReceive?
EDIT: As I pointed out in a comment below I think SUPPLICANT_CONNECTION_CHANGE_ACTION would be the best choice for me but it is never fired or received by my application. Others have the same problem with this broadcast but a real solution for this is never proposed (in fact other broadcasts are used). Any ideas for this?

You can go for WifiManager.NETWORK_STATE_CHANGED_ACTION works.
Register receiver with WifiManager.NETWORK_STATE_CHANGED_ACTION Action, either in Manifest or Fragment or Activity, which ever suited for you.
Override receiver :
#Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if(action.equals(WifiManager.NETWORK_STATE_CHANGED_ACTION)){
NetworkInfo info = intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);
boolean connected = info.isConnected();
if (connected)
//call your method
}
}

Please try
#Override
protected void onResume() {
super.onResume();
IntentFilter filter = new IntentFilter();
filter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
filter.addAction("android.net.wifi.STATE_CHANGE");
registerReceiver(networkChangeReceiver, filter);
}
#Override
protected void onDestroy() {
unregisterReceiver(networkChangeReceiver);
super.onDestroy();
}
and
BroadcastReceiver networkChangeReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
if (!AppUtils.hasNetworkConnection(context)) {
showSnackBarToast(getNetworkErrorMessage());
}
}
};
I am using this and it is working for me. Hope it will help you out.

Receiver, that was created from IntentService, doesn't work

I have Geofence IntentService. On GEOFENCE_ENTER I create broadcast receiver. But it doesn't get actions.
If I created it in MainActivity - all is good. But I don't need to.
I do not understand what happens when I create the receiver from the service.
public class GeofenceTransitionsIntentService extends IntentService {
...
#Override
protected void onHandleIntent(Intent intent) {
...
if (geofenceTransition == Geofence.GEOFENCE_TRANSITION_ENTER) {
//Create WiFi scan receiver
WiFiScanReceiver wifiScan = new WiFiScanReceiver();
registerReceiver(wifiScan, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
//Scan
WifiManager wm = (WifiManager) getSystemService(Context.WIFI_SERVICE);
Boolean scanStarted = wm.startScan();
}
}

Calling registerReceiver() in onHandleIntent() will not work well. Your receiver will go away microseconds later, after onHandleIntent() returns and the service stops itself.
Either use a manifest-registered receiver, or use a regular Service instead of an IntentService, managing your own background thread and arranging to stopSelf() the service when you are done with it.

IntentService will be destroyed once onHandleIntent() finished.
You should use Service

Detecting network status change and starting service from broadcast receiver

I have written the following code for detecting the network status from within the BroadcastReceiver. I start a service when the network is available and stop the service when the network is not available.
I have the following class level variable.
private boolean IsNetworkAlreadyConnected = false;
Within onCreate method of the main class I start the service if the internet is available.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (InternetConnectivity.isConnected(MainActivity.this)) {
IsNetworkAlreadyConnected = true;
Intent timerIntent = new Intent(getBaseContext(), InActivityTimer.class);
startService(timerIntent);
}
}
and below is the code for my BroadcastReceiver in the same class,
public class mConnectivityCheckReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (action.equals("android.net.conn.CONNECTIVITY_CHANGE")) {
try {
boolean networkAvailable = InternetConnectivity.isConnected(context);
if (networkAvailable) {
if (!IsNetworkAlreadyConnected) {
Intent timerIntent = new Intent(getBaseContext(), InActivityTimer.class);
startService(timerIntent);
IsNetworkAlreadyConnected = true;
}
else {
Log.d("KC_HomeActivity", "Network was already connected. No need to start service again.");
}
}
else {
Log.d("KC_HomeActivity", "Network Disconnected. Service Stopped.");
IsNetworkAlreadyConnected = false;
Intent timerIntent = new Intent(getBaseContext(), InActivityTimer.class);
stopService(timerIntent);
}
}
catch (Exception e) {
}
}
}
};
When both Mobile data and Wifi are turned on then the service is started from onCreate method and it is not started again in the BroadcastReceiver but when I turn off the Wifi the Android changes the network mode to Mobile Data but for few seconds there is no internet connectivity and the service is stopped and then started again. I don't want to do this. If there is no connectivity only then the service should be stopped. If the network is shifting from Wifi to Mobile Data then the service should not be stopped.
Note: To check the internet connectivity I am using,
NetworkInfo info = InternetConnectivity.getNetworkInfo(context);
return (info != null && info.isConnectedOrConnecting());

Network connections aren't that precise. You should make it relax a bit, or you'll pull your hair out.
I would implement a smoothing function from the broadcasts. When you get a connectivity change notification, set a timeout for like 15 seconds. At that time, check your status and either start, stop, or do nothing. If another broadcast comes in, clear the first and reset for another 15 seconds. That will give the device time to reconnect.

Broadcast Receiver in IntentService (Service has leaked IntentReceiver)

I try to implement an IntentService with a BroadcastReceiver that reacts on the SCAN_RESULTS_AVAILABLE_ACTION.
The IntentService is supposed to compare Lists whenever onReceive is called. I always get the
"Service has leaked IntentReceiver"
error even though I unregister the BroadcastReceiver in onDestroy().
Here is the code:
public class MyClass extends IntentService {
private HashMap<String, List<String>>;
private WifiManager mWifiManager;
private WifiReceiver mWifiReceiver;
public MyClass() {
super("MyClass");
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
mWifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
mWifiReceiver = new WifiReceiver();
registerReceiver(mWifiReceiver, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
mWifiManager.createWifiLock(WifiManager.WIFI_MODE_SCAN_ONLY,"ScanLock");
mWifiManager.setWifiEnabled(true);
return START_NOT_STICKY;
}
#Override
public void onDestroy(){
unregisterReceiver(mWifiReceiver);
mWifiManager.setWifiEnabled(false);
}
#Override
protected void onHandleIntent(Intent intent) {
// TODO Auto-generated method stub
}
class WifiReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
//Here I do my stuff with the scan results
//should be called every 5 seconds
}
}
Where is the problem in the code?
Why do I keep getting this error?
I still have to learn a lot about Android, but I think the IntentService is the right way to go since I do not expect any result from this class. It should just stop when I send a call stopService(). This IntentService is called by another IntentService! Is that a problem?
Thanks for helping.

I try to implement an IntentService with a BroadcastReceiver that reacts on the SCAN_RESULTS_AVAILABLE_ACTION.
This is largely pointless. Your receiver will be registered for a few seconds at most, hopefully.
I still have to learn a lot about Android, but I think the IntentService is the right way to go since I do not expect any result from this class.
That makes no sense whatsoever. You use an IntentService when you have a short bit of work that needs to be performed in a background thread. For example, if you use AlarmManager to check for new email messages every 15 minutes, or you have an activity kick off a large file download, you would use IntentService.
It should just stop when I send a call stopService().
You never call stopService() on an IntentService. The IntentService stops itself once onHandleIntent() returns. This is why your BroadcastReceiver will be removed within seconds -- your onHandleIntent() should only be running for seconds.
This IntentService is called by another IntentService!
This is unlikely to be a good design.

Try registering BroadcastReceiver in OnCreate() instead of OnStartCommand(),
That should fix your problem.

Problem in understanding broadcast receiver

I have an app in which I'm trying to detect WHEN the Internet connection appears and when it disappears.
At the moment, when it appears, I'm starting a new thread (different from the UI) which connects my app to a remote server.
For that I'm hardly trying to implement a broadcast receiver which LISTENS for connectivity, but I'm having problems in understanding the concept.
In my onCreate() I have somethig like:
onCreate()
{
cThread = new Thread(new ClientThread(syncToken));
cThread.start();
}
When there is connection to the Internet I'm sending data through the socket, when there is not I'm storing the data in a database. And when the Internet appears I'm restarting my thread to reconnect and send the old data (which hasn't been sent because of network crashing) and the new one.
Let's say I would implement something like this:
DoRefreshBroadcastReceiver refreshBroadcastReceiver;
...
onResume() {
// register the refreshing complete broadcast receiver
IntentFilter intentFilter = new IntentFilter(DO_REFRESH);
refreshBroadcastReceiver = new doRefreshBroadcastReceiver();
registerReceiver(refreshBroadcastReceiver, intentFilter);
}
public class DoRefreshBroadcastReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
// call method to run fetch code...
}
}
Does this mean that when the Internet connection is detected my onReceive() gets called? And I could start my thread there?
What is the concept of using an intent? Because I really don't get it. How to use it, and what its purpose?
THE IDEA: I don't really know how to use this intent in this case or how to use it in my app!
Would this thing detect the connection to the Internet even when I'm not in this activity?
EDIT:
Here is how my onReceive looks like:
onCreate()
{
cThread = new Thread(new ClientThread(syncToken));
// cThread.start();
connIntentFilter = new IntentFilter(
"android.net.conn.CONNECTIVITY_CHANGE");
connListener = new MyConnectivityListener();
}
public void onReceive(Context context, Intent intent)
{
mNetworkInfo = (NetworkInfo) intent
.getParcelableExtra(ConnectivityManager.EXTRA_NETWORK_INFO);
if (mNetworkInfo != null && mNetworkInfo.isConnected())
{
/*
* if(mNetworkInfo.getType()==ConnectivityManager.TYPE_WIFI);
*
*
* else
*/
cThread.start();
}
else {
System.out.println("There is no internet connection!");
try {
cThread.stop();
}
catch (Exception e) {
e.printStackTrace();
}
}
}
mNetworkInfo != null && mNetworkInfo.isConnected()
Does this mean it's connected or should I verify for a certain type of connection on the emulator?
*I think that I should start my thread directly in onReceive(). As soon as my app starts it detects the Internet connection and BroadcastReceiver gets fired, doesn't it?

Try something like this...
public class MyActivity extends Activity {
private MyConnectivityListener connListener = null;
private IntentFiler connIntentFilter = null;
private Boolean connIntentFilterIsRegistered = false;
#Override
protected void onCreate(...) {
...
connIntentFilter = new IntentFilter("android.net.conn.CONNECTIVITY_CHANGE");
connListener = new MyConnectivityListener();
}
#Override
protected void onResume() {
...
if (!connIntentFilterIsRegistered) {
registerReceiver(connListener, connIntentFilter);
connIntentFilterIsRegistered = true;
}
}
#Override
protected void onPause() {
...
if (connIntentFilterIsRegistered) {
unregisterReceiver(connListener);
connIntentFilterIsRegistered = false;
}
}
protected class MyConnectivityListener extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
// The NetworkInfo for the affected network is sent
// as an extra; it should be consulted to see what
// kind of connectivity event occurred.
}
}
}
A BroadcastReceiver is effectively a 'listener' which listens for events either sent by the system or, in some cases, by your own application components.
In this case, the system broadcasts android.net.conn.CONNECTIVITY_CHANGE whenever there is a connection change (connected/disconnected). By registering your BroadcastReceiver to 'listen' for that event, you can get the extra included in the Intent from your BroadcastReceiver's onReceive(...) method and do whatever you need to do accordingly. The extra is a `NetworkInfo object which will contain information about the particular network and whether it is connected or not.