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How to fix : System services not available to Activities before onCreate()?

I am making an android app that can send notifications even if the app is closed. So I added a NotificationService to call when the app is destroyed. But I get an error: System services not available to Activities before onCreate() when I force the app to stop.
This is the MainActivity.java:
public class MainActivity extends AppCompatActivity {
private Button button1;
private Button button2;
private Button button3;
private Button button4;
private static final String CHANNEL_ID = "telus";
private static final String CHANNEL_NAME = "telus app";
private static final String CHANNEL_DESC = "telus app notification";
private int count = 1;
Timer timer;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button1=(Button) findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
openActivity_web();
}
});
button2=(Button) findViewById(R.id.button2);
button2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
openActivationPage();
}
});
button3=(Button) findViewById(R.id.button3);
button3.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
openMysql();
}
});
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O){
NotificationChannel channel = new NotificationChannel(CHANNEL_ID, CHANNEL_NAME, NotificationManager.IMPORTANCE_DEFAULT);
channel.setDescription(CHANNEL_DESC);
NotificationManager manager = getSystemService(NotificationManager.class);
manager.createNotificationChannel(channel);
}
findViewById(R.id.button4).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
displayNotification();
}
});
class sendnotif extends TimerTask {
public void run() {
displayNotification();
}
}
Timer timer = new Timer();
timer.schedule(new sendnotif(), 0, 5000);
}
public void displayNotification(){
NotificationCompat.Builder mBuilder =
new NotificationCompat.Builder(this, CHANNEL_ID)
.setSmallIcon(R.drawable.ic_alarm)
.setContentTitle("Titre de la notification")
.setContentText("C'est le text de la notification")
.setPriority(NotificationCompat.PRIORITY_DEFAULT)
;
NotificationManagerCompat mNotifMgr = NotificationManagerCompat.from(this);
mNotifMgr.notify( 1, mBuilder.build());
}
public void openActivity_web(){
Intent intent = new Intent(this, WebPage.class);
startActivity(intent);
}
public void openActivationPage(){
Intent intent = new Intent(this, ActivationPage.class);
startActivity(intent);
}
public void openMysql(){
Intent intent = new Intent(this, mysql_display.class);
startActivity(intent);
}
protected void onDestroy(){
super.onDestroy();
startService(new Intent(this, NotificationService.class));
}
}
and this is the NotificationService.java:
public class NotificationService extends Service {
Timer timer;
TimerTask timerTask;
String TAG = "Timers";
int Your_X_SECS = 5;
#Override
public IBinder onBind(Intent arg0) {
return null;
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.e(TAG, "onStartCommand");
super.onStartCommand(intent, flags, startId);
startTimer();
return START_STICKY;
}
#Override
public void onCreate() {
Log.e(TAG, "onCreate");
}
#Override
public void onDestroy() {
Log.e(TAG, "onDestroy");
stoptimertask();
super.onDestroy();
}
//we are going to use a handler to be able to run in our TimerTask
final Handler handler = new Handler();
public void startTimer() {
//set a new Timer
timer = new Timer();
//initialize the TimerTask's job
initializeTimerTask();
//schedule the timer, after the first 5000ms the TimerTask will run every 10000ms
timer.schedule(timerTask, 5000, Your_X_SECS * 1000); //
//timer.schedule(timerTask, 5000,1000); //
}
public void stoptimertask() {
//stop the timer, if it's not already null
if (timer != null) {
timer.cancel();
timer = null;
}
}
public void initializeTimerTask() {
timerTask = new TimerTask() {
public void run() {
//use a handler to run a toast that shows the current timestamp
handler.post(new Runnable() {
public void run() {
MainActivity notif = new MainActivity();
notif.displayNotification();
}
});
}
};
}
}
This is the error log when I try to manually stop the app:
2019 - 07 - 16 20: 10: 23.079 23334 - 23334 / com.example.testapp E / AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.testapp, PID: 23334
java.lang.IllegalStateException: System services not available to Activities before onCreate()
at android.app.Activity.getSystemService(Activity.java: 5581)
at androidx.core.app.NotificationManagerCompat. < init > (NotificationManagerCompat.java: 158)
at androidx.core.app.NotificationManagerCompat.from(NotificationManagerCompat.java: 153)
at com.example.testapp.MainActivity.displayNotification(MainActivity.java: 103)
at com.example.testapp.NotificationService$1$1.run(NotificationService.java: 89)
at android.os.Handler.handleCallback(Handler.java: 751)
at android.os.Handler.dispatchMessage(Handler.java: 95)
at android.os.Looper.loop(Looper.java: 154)
at android.app.ActivityThread.main(ActivityThread.java: 6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java: 866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java: 756)
Thank you for your help.

How I can create a Background service in android?

I need to create a service that allow my application to work also when I close it, I’ve tried with STICKY_SERVICE but it doesn’t work... if anyone can decribe me how I can do this please answer this question.
It works with android 7.1 and it doesn’t with other versions
Here is my code...
public class SensorService extends Service {
public int counter=0;
public SensorService(Context applicationContext) {
super();
Log.i("HERE", "here I am!");
}
public SensorService() {
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
super.onStartCommand(intent, flags, startId);
startTimer();
return START_STICKY;
}
#Override
public void onDestroy() {
super.onDestroy();
Log.i("EXIT", "ondestroy!");
stoptimertask();
Intent broadcastIntent = new Intent("RestartSensor");
sendBroadcast(broadcastIntent);
}
private Timer timer;
private TimerTask timerTask;
long oldTime=0;
public void startTimer() {
//set a new Timer
timer = new Timer();
//initialize the TimerTask's job
initializeTimerTask();
//schedule the timer, to wake up every 1 second
timer.schedule(timerTask, 1000, 1000); //
}
/**
* it sets the timer to print the counter every x seconds
*/
public void initializeTimerTask() {
timerTask = new TimerTask() {
public void run() {
Log.i("in timer", "in timer ++++ "+ (counter++));
}
};
}
/**
* not needed
*/
public void stoptimertask() {
//stop the timer, if it's not already null
if (timer != null) {
timer.cancel();
timer = null;
}
}
#Nullable
#Override
public IBinder onBind(Intent intent) {
return null;
}
}
This is my service Restarter...
public class SensorRestarterBroadcastReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
Log.i(SensorRestarterBroadcastReceiver.class.getSimpleName(), "Service Stops");
context.startService(new Intent(context, SensorService.class));
}
}
And the mainClass
public class MainActivity extends AppCompatActivity {
Intent mServiceIntent;
private SensorService mSensorService;
Context ctx;
public Context getCtx() {
return ctx;
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ctx = this;
setContentView(R.layout.activity_main);
mSensorService = new SensorService(getCtx());
mServiceIntent = new Intent(getCtx(), mSensorService.getClass());
if (!isMyServiceRunning(mSensorService.getClass())) {
startService(mServiceIntent);
}
}
private boolean isMyServiceRunning(Class<?> serviceClass) {
ActivityManager manager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
if (serviceClass.getName().equals(service.service.getClassName())) {
Log.i ("isMyServiceRunning?", true+"");
return true;
}
}
Log.i ("isMyServiceRunning?", false+"");
return false;
}
#Override
protected void onDestroy() {
stopService(mServiceIntent);
Log.i("MAINACT", "onDestroy!");
super.onDestroy();
}
}
This restartthe service correctly but after 3/4 seconds it die.
I've added this to my manifest
<service
android:name=".SensorService"
android:enabled="true" >
</service>
<receiver
android:name=".SensorRestarterBroadcastReceiver"
android:enabled="true"
android:exported="true"
android:label="RestartServiceWhenStopped">
<intent-filter>
<action android:name="RestartSensor"/>
</intent-filter>
</receiver>

Add the following code to your sensor service and edit as per your need. You need to bind the sticky service to a notification to keep the service alive and start in the foreground.
#Override
public void onCreate() {
super.onCreate();
Intent notifIntent = new Intent(this, SensorService.class);
PendingIntent pi = PendingIntent.getActivity(this, 0, notifIntent, 0);
Notification notification = new NotificationCompat.Builder(this)
.setSmallIcon(R.drawable.smslogo_100x100)
.setColor(ContextCompat.getColor(this, R.color.colorAccent))
.setContentTitle(getResources().getString(R.string.app_name))
.setContentText("Running")
.setContentIntent(pi)
.build();
startForeground(101010, notification);
}
This will rectify the issue you are facing and the service will run forever.

Passing the string value to background service

Please guide me in this. Appreciate all your help.
My background service is toasting ABC
//-------------------String displayingText = "ABC";-----------------
And I have two strings, ABC and DEF declared in mainactivity.java
How do I pass the value displayingText from main activity to this service.
How do I change the displayingText to DEF after the toast ABC finished.
MyService.Java
public class MyService extends Service {
public static final long INTERVAL=3000;//variable to execute services every 5 second
private Handler mHandler=new Handler(); // run on another Thread to avoid crash
private Timer mTimer=null; // timer handling
//the get intent dont work. where or how should i put it?
Intent myIntent = getIntent();
if (myIntent !=null && myIntent.getExtras()!=null)
String value = myIntent.getExtras().getString(PassToService);
#Nullable
#Override
public IBinder onBind(Intent intent) {
throw new UnsupportedOperationException("unsupported Operation");
}
#Override
public void onCreate() {
// cancel if service is already existed
if(mTimer!=null)
mTimer.cancel();
else
mTimer=new Timer(); // recreate new timer
mTimer.scheduleAtFixedRate(new TimeDisplayTimerTask(),0,INTERVAL);// schedule task
}
#Override
public void onTaskRemoved(Intent rootIntent) {
stopSelf();///its will stop service
super.onTaskRemoved(rootIntent);
}
#Override
public void onDestroy() {
Toast.makeText(this, "In Destroy", Toast.LENGTH_SHORT).show();//display toast when method called
mTimer.cancel();//cancel the timer
super.onDestroy();
}
//inner class of TimeDisplayTimerTask
private class TimeDisplayTimerTask extends TimerTask {
#Override
public void run() {
// run on another thread
mHandler.post(new Runnable() {
#Override
public void run() {
// display toast at every 10 second
//String displayingText = "ABC";
String displayingText = myIntent.getStringExtra("PassToService");
final Toast Notify = Toast.makeText(getApplicationContext(), displayingText, Toast.LENGTH_SHORT);
Notify.setGravity(Gravity.CENTER, 0, 0);
Notify.show();
Handler cancelToast = new Handler();
cancelToast.postDelayed(new Runnable() {
#Override
public void run() {
Notify.cancel();
}
}, 1000);
}
});
}
}
}

You can do it by passing value from activity to service-
startService(new Intent(YourActivity.Service.class).putExtra("key","value"));

Android java.lang.RuntimeException: Error receiving broadcast Intent

As soon as my application starts I get a crash and I can't figure out why. I have a Service that is used as a timer to count the number of seconds since the timer started, this then gets passed back to my MainActivity.
MainActivity.java:
public class MainActivity extends AppCompatActivity {
private static final String TAG = "BroadcastTest";
private Intent intent;
private Chronometer timer;
private Button start;
private Button stop;
private EditText hourlyRate;
private TextView money;
private long timeWhenStopped = 0;
private double moneyEarned;
private double secondsRate;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
timer = (Chronometer) findViewById(R.id.chronometer);
start = (Button) findViewById(R.id.start);
stop = (Button) findViewById(R.id.stop);
hourlyRate = (EditText) findViewById(R.id.hourlyRate);
money = (TextView) findViewById(R.id.money);
intent = new Intent(this, Timer.class);
start.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startService(new Intent(MainActivity.this, Timer.class));
timer.setBase(SystemClock.elapsedRealtime() + timeWhenStopped);
timer.start();
}
});
stop.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
timeWhenStopped = timer.getBase() - SystemClock.elapsedRealtime();
timer.stop();
}
});
timer.setOnChronometerTickListener(new Chronometer.OnChronometerTickListener()
{
#Override
public void onChronometerTick(Chronometer chronometer){
long timeElapsed = SystemClock.elapsedRealtime() - timer.getBase();
int seconds = (int) timeElapsed / 1000;
double hrlyRate = Double.parseDouble(hourlyRate.getText().toString());
secondsRate = (hrlyRate / 60) / 60;
moneyEarned = secondsRate * seconds;
double displayMoney = Math.round(moneyEarned * 100.0)/100.0;
Log.d("hours",Long.toString(seconds));
money.setText("$"+Double.toString(displayMoney));
}
});
}
private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
updateUI(intent);
}
};
#Override
public void onResume() {
super.onResume();
startService(intent);
registerReceiver(broadcastReceiver, new IntentFilter(Timer.BROADCAST_ACTION));
}
#Override
public void onPause() {
super.onPause();
unregisterReceiver(broadcastReceiver);
stopService(intent);
}
private void updateUI(Intent intent) {
String counter = intent.getStringExtra("counter");
Log.d("SERVICE_SECONDS", counter);
}
}
Timer.java:
public class Timer extends Service {
private static final String TAG = "BroadcastService";
public static final String BROADCAST_ACTION = "b.calvin.com.dirtymoney";
private final Handler handler = new Handler();
Intent intent;
int counter = 0;
private Runnable sendUpdatesToUI = new Runnable() {
public void run() {
countSeconds();
handler.postDelayed(this, 1000); // 1 second
}
};
#Override
public void onCreate()
{
super.onCreate();
intent = new Intent(BROADCAST_ACTION);
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
handler.removeCallbacks(sendUpdatesToUI);
handler.postDelayed(sendUpdatesToUI, 0); // 1 second
Toast.makeText(this, "service starting", Toast.LENGTH_SHORT).show();
return START_STICKY;
}
#Override
public IBinder onBind(Intent intent) {
return null;
}
private void countSeconds() {
Log.d(TAG, Integer.toString(++counter));
sendBroadcast(intent);
}
}
Error:
FATAL EXCEPTION: main
Process: b.calvin.com.dirtymoney, PID: 3348
java.lang.RuntimeException: Error receiving broadcast Intent { act=b.calvin.com.dirtymoney flg=0x10 } in b.calvin.com.dirtymoney.MainActivity$4#bf337ff
at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:891)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: println needs a message
at android.util.Log.println_native(Native Method)
at android.util.Log.d(Log.java:139)
at b.calvin.com.dirtymoney.MainActivity.updateUI(MainActivity.java:113)
at b.calvin.com.dirtymoney.MainActivity.access$600(MainActivity.java:20)
at b.calvin.com.dirtymoney.MainActivity$4.onReceive(MainActivity.java:93)
at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:881)
at android.os.Handler.handleCallback(Handler.java:739) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:148) 
at android.app.ActivityThread.main(ActivityThread.java:5417) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

Seems like you forgot to put your counter variable into the Intent, so you're passing null to Log.d() as the message, resulting in a NullPointerException.
Something like this should work:
private void countSeconds() {
Log.d(TAG, Integer.toString(++counter));
Intent counterIntent = new Intent(BROADCAST_ACTION);
counterIntent.putExtra("counter", counter);
sendBroadcast(counterIntent);
}
Also, counter is an int, so you should call getIntExtra() instead of getStringExtra():
private void updateUI(Intent intent) {
int counter = intent.getIntExtra("counter");
Log.d("SERVICE_SECONDS", Integer.toString(counter));
}

Error notification when i close my app

i am doing an application that will notify the user after 2 weeks. but i set the timer in 2 mins so i could test if my application will notify the user. my problem is when i turn on the notification and close my app. i will get an error in 2 minutes no notification but when my app is running the notification is working fine. In the logcat my error is in Bundle showData = i.getExtras(); i think the problem is when i closed my app, the Bundle passData is getting null?
PhoneInformation.java
case R.id.bTurnOn:
Bundle passData = new Bundle();
Intent intent = new Intent(PhoneInformation.this,NotificationService.class);
passData.putInt("keyid", rowId);
intent.putExtras(passData);
startService(intent);
break;
NotificationService.java
public class NotificationService extends Service{
int rowId;
private Timer timer = new Timer();
#Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}
#Override
public void onCreate() {
// TODO Auto-generated method stub
super.onCreate();
Toast.makeText(this, "OnCreate()", Toast.LENGTH_SHORT).show();
}
#Override
public void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
Toast.makeText(this, "OnDestroy()", Toast.LENGTH_SHORT).show();
}
#Override
#Deprecated
public void onStart(final Intent i, int startId) {
// TODO Auto-generated method stub
super.onStart(i, startId);
final Handler handler = new Handler();
Timer timer;
TimerTask timertask = new TimerTask() {
#Override
public void run() {
handler.post(new Runnable() {
#SuppressWarnings("deprecation")
public void run() {
Bundle showData = i.getExtras();
rowId = showData.getInt("keyid");
Bundle passData = new Bundle();
NotificationManager nm = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
Intent notificationIntent = new Intent(NotificationService.this,SMSPhoneMessage.class);
passData.putInt("keyid", rowId);
notificationIntent.putExtras(passData);
PendingIntent pendingIntent = PendingIntent.getActivity(NotificationService.this, 0, notificationIntent, Intent.FLAG_ACTIVITY_NEW_TASK);
Notification notification = new Notification(R.drawable.ic_launcher, "New Message", System.currentTimeMillis());
notification.setLatestEventInfo(NotificationService.this, "New Message", "Please come to me immediately", pendingIntent);
nm.notify(123, notification);
}
});
}
};
timer = new Timer();
timer.schedule(timertask, 10000);
}
}