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Forked from Aeonitis/MainActivity.java
Created August 13, 2020 01:02
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Android - Check Network State in your app, Notifying you when an app is online/offline
/**
* This would be the activity which registers the receiver class via it's interface
*/
public class MainActivity implements NetworkStateReceiver.NetworkStateReceiverListener {
private NetworkStateReceiver networkStateReceiver; // Receiver that detects network state changes
@Override
protected void onCreate(Bundle savedInstanceState) {
/***/
startNetworkBroadcastReceiver(this);
}
@Override
protected void onPause() {
/***/
unregisterNetworkBroadcastReceiver(this);
super.onPause();
}
@Override
protected void onResume() {
/***/
registerNetworkBroadcastReceiver(this);
super.onResume();
}
@Override
public void networkAvailable() {
Log.i(TAG, "networkAvailable()");
//Proceed with online actions in activity (e.g. hide offline UI from user, start services, etc...)
}
@Override
public void networkUnavailable() {
Log.i(TAG, "networkUnavailable()");
//Proceed with offline actions in activity (e.g. sInform user they are offline, stop services, etc...)
}
public void startNetworkBroadcastReceiver(Context currentContext) {
networkStateReceiver = new NetworkStateReceiver();
networkStateReceiver.addListener((NetworkStateReceiver.NetworkStateReceiverListener) currentContext);
registerNetworkBroadcastReceiver(currentContext);
}
/**
* Register the NetworkStateReceiver with your activity
* @param currentContext
*/
public void registerNetworkBroadcastReceiver(Context currentContext) {
currentContext.registerReceiver(networkStateReceiver, new IntentFilter(android.net.ConnectivityManager.CONNECTIVITY_ACTION));
}
/**
Unregister the NetworkStateReceiver with your activity
* @param currentContext
*/
public void unregisterNetworkBroadcastReceiver(Context currentContext) {
currentContext.unregisterReceiver(networkStateReceiver);
}
}
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.util.Log;
import java.util.ArrayList;
import java.util.List;
/**
* NetworkStateReceiver defines a BroadcastReceiver which allows us to register for system (i.e. network status) or application events.
* All registered receivers for an event are notified by the Android runtime once this event happens.
* Source: http://stackoverflow.com/questions/6169059/android-event-for-internet-connectivity-state-change
*/
public class NetworkStateReceiver extends BroadcastReceiver {
protected List<NetworkStateReceiverListener> listeners;
protected Boolean connected;
private String TAG = "NetworkStateReceiver";
public NetworkStateReceiver() {
listeners = new ArrayList<>();
connected = null;
}
/**
* Called when the BroadcastReceiver is receiving an Intent broadcast (event for which the broadcast receiver has registered occurs).
* During this time you can use the other methods on BroadcastReceiver to view/modify the current result values.
* NOTE: When it runs on the main thread you should never perform long-running operations in it (there is a timeout of 10 seconds that the system allows before considering the receiver to be blocked and a candidate to be killed).
* NOTE: You cannot launch a popup dialog in your implementation of onReceive().
* @param context Object to access additional information or to start services or activities
* @param intent Object with action used to register your receiver. This object contains additional information (e.g. extras)
*/
public void onReceive(Context context, Intent intent) {
Log.i(TAG, "Intent broadcast received");
if(intent == null || intent.getExtras() == null)
return;
// Retrieve a ConnectivityManager for handling management of network connections
ConnectivityManager manager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
// Details about the currently active default data network. When connected, this network is the default route for outgoing connections
NetworkInfo networkInfo = manager.getActiveNetworkInfo();
/**
* NOTE: getActiveNetworkInfo() may return null when there is no default network e.g. Airplane Mode
*/
if(networkInfo != null && networkInfo.getState() == NetworkInfo.State.CONNECTED) {
connected = true;
} else if(intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY, Boolean.FALSE)) { //Boolean that indicates whether there is a complete lack of connectivity
connected = false;
}
notifyStateToAll();
} //After the onReceive() of the receiver class has finished, the Android system is allowed to recycle the receiver
/**
* Notify the state to all needed methods
*/
private void notifyStateToAll() {
Log.i(TAG, "Notifying state to " + listeners.size() + " listener(s)");
for(NetworkStateReceiverListener eachNetworkStateReceiverListener : listeners)
notifyState(eachNetworkStateReceiverListener);
}
/**
* Notify the network state, triggering interface functions based on the current state
* @param networkStateReceiverListener Object which implements the NetworkStateReceiverListener interface
*/
private void notifyState(NetworkStateReceiverListener networkStateReceiverListener) {
if(connected == null || networkStateReceiverListener == null)
return;
if(connected == true) {
// Triggering function on the interface towards network availability
networkStateReceiverListener.networkAvailable();
} else {
// Triggering function on the interface towards network being unavailable
networkStateReceiverListener.networkUnavailable();
}
}
/**
* Adds a listener to the list so that it will receive connection state change updates
* @param networkStateReceiverListener Object which implements the NetworkStateReceiverListener interface
*/
public void addListener(NetworkStateReceiverListener networkStateReceiverListener) {
Log.i(TAG, "addListener() - listeners.add(networkStateReceiverListener) + notifyState(networkStateReceiverListener);");
listeners.add(networkStateReceiverListener);
notifyState(networkStateReceiverListener);
}
/**
* Removes listener (when no longer necessary) from the list so that it will no longer receive connection state change updates
* @param networkStateReceiverListener Object which implements the NetworkStateReceiverListener interface
*/
public void removeListener(NetworkStateReceiverListener networkStateReceiverListener) {
listeners.remove(networkStateReceiverListener);
}
/**
* Inner Interface (i.e. to encapsulate behavior in a generic and re-usable way) which handles connection state changes for classes which registered this receiver (Outer class NetworkStateReceiver)
* This interface implements the 'Strategy Pattern', where an execution strategy is evaluated and applied internally at runtime
*/
public interface NetworkStateReceiverListener {
/**
* When the connection state is changed and there is a connection, this method is called
*/
void networkAvailable();
/**
* Connection state is changed and there is not a connection, this method is called
*/
void networkUnavailable();
}
}
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