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Keep changes made by BroadcastReceiver

I'm stuck at this point:
private BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
Bundle bundle = intent.getExtras();
String number = bundle.getString("Time");
GameTime.setText("" +number + " hours");
}
};
In another Activity, when a Button is pressed, the MainActivity get's an int.
Whenever I open the Activity, I cannot see the GameTime TextView with the number variable in it.
I know that the OnReceive method works, beacause I had put a toast in it, and I could see the toast after sending the int from the other Activity.
How can I keep the changes made to the TextView while changing Activities?
Thank you.

One way:
Define an interface in your activity & Implement the interface inside your activity and pass its reference to the other class and call that reference whenever you need.
Example:
a) Create an interface
public interface MyBroadcastListener{
public void doSomething(String result);
}
b) Initialize BroadCastReceiver
public class TestNotifAlarm extends BroadcastReceiver {
private MyBroadcastListener listener;
#Override
public void onReceive(Context context, Intent intent) {
listener = (MyBroadcastListener)context;
listener.doSomething("Some Result");
}
}
c) Implement the interface in Activity
public YourActivity extends AppCompatActivity implements MyBroadcastListener{
// Your Activity code
public void updateTheTextView(String t) {
TextView textView = (TextView) findViewById(R.id.textView);
textView.setText(t);
}
#Override
public void doSomething(String result){
updateTheTextView(result); // Calling method from Interface
}
}
Another Way :
a) Put a Receiver inside your Activity class
BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
textView.setText(intent.getStringExtra("extra"));
}
};
b) Register BroadCastReceiver
registerReceiver(broadcastReceiver , new IntentFilter("trigger_broadcust"));
c) Call sendBroadcast
Intent intent = new Intent("trigger_broadcust");
intent.putStringExtra("extra", "data");
sendBroadcast(intent);

How to check internet connectivity using broadcast receiver and Change the intent

I am working on an Android application which requires constant listener of Internet connectivity. I am using Broadcast listener and successfully applied it. But my code only shows the Toast message.
I want to stop the current activity and show a default XML file which says "No Internet Connection". and whenever it connect the Internet, previous activity resumes.
ExampleBradcastReceiver.java
public class ExampleBroadcastReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
if (ConnectivityManager.CONNECTIVITY_ACTION.equals(intent.getAction())) {
boolean noConnectivity = intent.getBooleanExtra(
ConnectivityManager.EXTRA_NO_CONNECTIVITY, false
);
if (noConnectivity) {
Toast.makeText(context, "Disconnected", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(context, "Connected", Toast.LENGTH_SHORT).show();
}
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity {
ExampleBroadcastReceiver exampleBroadcastReceiver = new ExampleBroadcastReceiver();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
protected void onStart() {
super.onStart();
IntentFilter filter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
registerReceiver(exampleBroadcastReceiver, filter);
}
#Override
protected void onStop() {
super.onStop();
unregisterReceiver(exampleBroadcastReceiver);
}
}
In the place of Toast Message, I want to show a default XML file whenever disconnected and resume activity whenever connected.

You can move ExampleBroadcastReceiver to MainActivity as an inner class. And since in Java inner classes have access to their parent classes' methods and fields, you can in onReceive method consider showing/hiding the Internet disconnected view.
public class MainActivity extends AppCompatActivity {
ExampleBroadcastReceiver exampleBroadcastReceiver = new ExampleBroadcastReceiver();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
protected void onStart() {
super.onStart();
IntentFilter filter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
registerReceiver(exampleBroadcastReceiver, filter);
}
#Override
protected void onStop() {
super.onStop();
unregisterReceiver(exampleBroadcastReceiver);
}
private void showInternetDisconnectedView(boolean disconnected){
// show or hide based on 'disconnected'
}
private class ExampleBroadcastReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
if (ConnectivityManager.CONNECTIVITY_ACTION.equals(intent.getAction())) {
boolean noConnectivity = intent.getBooleanExtra(
ConnectivityManager.EXTRA_NO_CONNECTIVITY, false);
showInternetDisconnectedView(noConnectivity);
}
}
}
}

You need to move Broadcast receiver code into Activity and on receiving internet connection events you can stop current in progress activity and make internet failure layout visible there only as it is part of Activity class. If it is required through out the Application, then create Base activity and handle this there to avoid duplicating code on every screen.

Create service to detect any action from the user

I'm trying to create a service where I want to detect something about user, let's say when user lays the device on a table, the thing is that I have that action detected but I have it on a MainActivty and I want it to put on Service.
The thing is that on my MainActivity() I had my registerAction() and on my onResume() were called and in onPause() I call the unregisterListener() from my sensor, as well I have a HandlerThread where I start it on my onCreate() how do I change it to Service? Would be a problem? I see that there aren't the same methods...
I've created my Service and I've got :
public class MyService extends Service {
public MyService() {
}
#Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
#Override
public void onCreate() {
super.onCreate();
Log.d("CREATE","ONCREATE");
}
#Override
public void onDestroy() {
super.onDestroy();
Log.d("DESTROY","ONDESTROY");
}
}
Also my MainActivity I have put implements SensorEventListener.
A skeleton of my class is :
public class MainActivity extends Activity implements SensorEventListener {
private HandlerThread mSensorThread;
private SensorManager mSensorManager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
mSensorThread = new HandlerThread("sensor_thread");
mSensorThread.start();
}
private void registerSensorListener() {
mSensorManager.registerListener(this, sensor, SensorManager.SENSOR_DELAY_FASTEST, new Handler(mSensorThread.getLooper()));
}
#Override
public void onSensorChanged(SensorEvent event) {
//DO stuff
if (isLayed()) {
runOnUiThread(new Runnable() {
#Override
public void run() {
Log.d("LAY","LAYLAY");
}
});
mSensorManager.unregisterListener(this);
}
}
#Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
private boolean isLayed() {
return stuff;
}
#Override
protected void onResume() {
super.onResume();
registerSensorListener();
}
#Override
protected void onPause() {
super.onPause();
mSensorManager.unregisterListener(this);
}
}
EDIT
I'm using szamani20 code, but I'm having problems with runOnUiThread because I can not call from my Service also, I'm having this issue
java.lang.RuntimeException: Unable to start service com.example.developer.qwe.MyService#d8c613b with null: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Intent.getAction()' on a null object reference

First of all you need to decide whether you want the user to be aware of your running service or not. Take a review on Background Execution Limits in android Oreo:
To improve the user experience, Android 8.0 (API level 26) imposes limitations on what apps can do while running in the background.
So considering your case where it seems there are lots of work to do in many situations, it would be a better approach to use a foreground service. As android document says about foreground services:
A foreground service is a service that the user is actively aware of and is not a candidate for the system to kill when low on memory. A foreground service must provide a notification for the status bar, which is placed under the Ongoing heading. This means that the notification cannot be dismissed unless the service is either stopped or removed from the foreground.
Since you mentioned that you have the action detected I won't enter that part of your code. So you need to create a subclass of Service as you did and use the startService method to get it's onCreate called. One thing you need to notice is that the onCreate method of service is called once you call startService on that service for the first time, no matter how many times you call startService again the onCreate method won't get called and only the onStartCommand get called. We use that fact alongside that you could provide a string action within your intent to properly register and unregister your listener.
In MainActivity.java:
String action = "start"; // Or to unregister listener "stop"!
final Intent intent = new Intent(this, MyService.class);
intent.setAction(action);
startService(intent);
and then in MyService.java:
#Override
public void onCreate() {
super.onCreate();
// Do initialization or whatever here (executed once per service lifecycle)
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
if (intent.getAction().equals("start")) {
// Register your listener or whatever
showForegroundNotification();
}
if (intent.getAction().equals("stop")) {
// Unregister your listener or whatever
stopForeground(true);
stopSelf();
}
return START_STICKY;
}
private void showForegroundNotification() {
Intent myServiceNotificationIntent = new Intent(this, MainActivity.class);
myServiceNotificationIntent.setFlags(
Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
PendingIntent pendingIntent = PendingIntent
.getActivity(this, MY_SERVICE_REQUEST_CODE,
myServiceNotificationIntent, MY_SERVICE_FLAG);
Notification notification = new NotificationCompat.Builder(this)
.setContentTitle(MY_SERVICE_NOTIFICATION_CONTENT_TITLE)
.setTicker(MY_SERVICE_NOTIFICATION_TICKER)
.setContentText(MY_SERVICE_NOTIFICATION_CONTENT_TEXT)
.setSmallIcon(R.drawable.ic_whatever)
.setContentIntent(pendingIntent)
.setOngoing(true)
.build();
startForeground(MY_SERVICE_NOTIFICATION_ID, notification);
}
Finally don't forget to unregister your listener in onDestroy in case of android kill your service (which is very rare):
#Override
public void onDestroy() {
super.onDestroy();
// Unregister your listener
}

You can register SensorManager inside service in OnStartCommand.Also try using startForeground as android os will kill your service when app is killed

How to pause game when user turn off screen

I have problem with one of my games. This is time based puzzle game and I have problem with it. When user press on/off button on Android device game doesn`t stop, but timer goes on and on till game over. When user turn on screen again, he can see game over screen. But I want to make scenario when user press on/off button game will pause.
Any suggestions? I`m pretty new in programming so please explain me very basic method to do this.
Thanks all!
Edit. Timer code
private void initializeProgressBar() {
//initialize progressbar
progress = ApplicationConstants.GAME_TIME;
mProgress = (ProgressBarDetermininate) findViewById(R.id.progressDeterminate);
mProgress.setMax(progress);
mProgress.setProgress(progress );
timer = new Timer();
progressBarUpdateTask = new ProgressBarUpdateTask();
timer.schedule(progressBarUpdateTask, 20, 20);
}
class ProgressBarUpdateTask extends TimerTask {
#Override
public void run() {
runOnUiThread(new Runnable(){
#Override
public void run() {
progress-=1;
if(progress==0)
{
TimeOver();
}
mProgress.setProgress(progress);
}
});
}
#Override
protected void onResume() {
super.onResume();
}
#Override
protected void onPause() {
super.onPause();
this.timer.cancel();
}

Pause your game in onStop() or onPause() (depending on your need) in the Activity context your game is running in.

I am assuming you are using android's activity...
#Override
protected void onResume() {
super.onResume();
// Resume the timer or show a button for the user to press when ready
// !!! Also check if timer exits because onResume is called before onCreate!!!
}
#Override
protected void onPause() {
super.onPause();
// Pause the timer
}

When you press screen off or Power button onPause method of the application will be called and when you again press Power button, applications onResume method will be called, you should pause timer in onPause and resume it in onResume.

One way to do this is to detect the user presence, here's an example
At beginning of your game start the LockService
startService(new Intent(getApplicationContext(), LockService.class));
LockService.java
public class LockService extends Service {
#Override
public IBinder onBind(Intent intent) {
return null;
}
#Override
public void onCreate() {
super.onCreate();
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
final IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);
filter.addAction(Intent.ACTION_SCREEN_OFF);
filter.addAction(Intent.ACTION_USER_PRESENT);
final BroadcastReceiver mReceiver = new ScreenReceiver();
registerReceiver(mReceiver, filter);
return super.onStartCommand(intent, flags, startId);
}
public class LocalBinder extends Binder {
LockService getService() {
return LockService.this;
}
}
}
Then finally the BroadcastReceiver where you can stop your game.
ScreenReceiver.java
public class ScreenReceiver extends BroadcastReceiver {
public static boolean wasScreenOn = true;
#Override
public void onReceive(final Context context, final Intent intent) {
Log.e("LOB","onReceive");
if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF)) {
// do whatever you need to do here
wasScreenOn = false;
/* PAUSE THE GAME HERE*/
Log.e("LOB","wasScreenOn"+wasScreenOn);
} else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {
// and do whatever you need to do here
wasScreenOn = true;
}else if(intent.getAction().equals(Intent.ACTION_USER_PRESENT)){
}
}
}
As correctly mentioned in other answers, you can also use the onPause() method
#Override
protected void onPause() {
super.onPause();
// stop the game
}

Wifi Broadcast android inside android intent

I'm learning android and I'm stuck here:
The app which I'm writing scans for Wifi signals in background periodically. I am using android intent service for the same. The problem is, application never executes onReceive() method of BroadCastReceiver
Intent Code:
public class BackgroundIntent extends IntentService {
// Default Constructor
public BackgroundIntent() {
super("BackgroundIntent");
// TODO Auto-generated constructor stub
}
WifiManager mainWifi;
BroadcastReceiver receiverWifi;
private final Handler handler = new Handler();
#TargetApi(Build.VERSION_CODES.GINGERBREAD)
#Override
protected void onHandleIntent(Intent intent) {
// TODO Auto-generated method stub
// Get mainWifi
mainWifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
if (mainWifi.isWifiEnabled() == false) {
mainWifi.setWifiEnabled(true);
}
receiverWifi = new WifiReceiver();
doInback();
}
// Basically a thread which calls itself after 5000milli sec
public void doInback() {
handler.postDelayed(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
mainWifi.startScan();
Log.i("Inside ", "doInBack");
// Call itself CODE GOES HERE :D
doInback();
}
}, 5000);
}
public class WifiReceiver extends BroadcastReceiver {
#TargetApi(Build.VERSION_CODES.GINGERBREAD)
public void onReceive(Context c, Intent intent) {
// CODE NEVER GOES HERE :(
List<ScanResult> wifiList;
wifiList = mainWifi.getScanResults();
Log.i("Inside receiver", "yes");
}
}
}
MainActivity code which invokes android intent service
public class MainActivity extends Activity {
TextView texty;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Intent is called here
Intent myIntent = new Intent(MainActivity.this, BackgroundIntent.class);
startService(myIntent);
texty = (TextView) findViewById(R.id.textView1);
}
public boolean onMenuItemSelected(int featureId, MenuItem item) {
return super.onMenuItemSelected(featureId, item);
}
}
Any idea what may be the cause? Is this wrong way to implement background wifi signal scan.
The same when I implement in Main Activity runs fine, so I'm guessing AndroidManifest.xml is correctly written..

Edit: I might've misinterpreted your goal here, If your just wondering why your onReceive() isn't firing, your activity has to register the receiver. Something like the following:
receiverWifi = new WifiReceiver();
registerReceiver(receiverWifi, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
doInback();
Check out this link

So the issue was with the functions which I was using.
I was using onHandleIntent(intent) which is the wrong function. Right one is onStartCommand(intent, flags, startId) for service.
My bad sorry..