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onReceive() function of a broadcastreceiver is not called, Kotlin, Android

I am trying to establish a basic alarm service. The code for set up the alarm looks like this. I have 15 minutes interval just to see if anything happens.
val alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
val intent = Intent(this, AlarmReceiver::class.java)
val pendingIntent = PendingIntent.getActivity(
applicationContext,
0,
intent,
PendingIntent.FLAG_IMMUTABLE)
val calendar = Calendar.getInstance()
calendar.set(Calendar.HOUR_OF_DAY, 20)
calendar.set(Calendar.MINUTE, 40)
calendar.set(Calendar.SECOND, 0)
alarmManager.setRepeating(AlarmManager.RTC, calendar.timeInMillis, AlarmManager.INTERVAL_FIFTEEN_MINUTES, pendingIntent)
I registered the receiver in the manifest file:
<application>
...
<receiver
android:name=".AlarmReceiver"
android:enabled="true"
android:exported="false" />
</application>
in addition i defined a permission, too in the manifest file
<uses-permission android:name="android.permission.SCHEDULE_EXACT_ALARM" />
The onReceive function of the AlarmReceiver class is not called.
I have a println line included. It does not print out anything.
I have no idea what I can do to make the alarm working.
Any hints are welcome.
thank you in advance
br,
Peter

Use PendingIntent.getBroadcast() when creating the PendingIntent instead of PendingIntent.getActivity()

Daily notification cannot start after installing

I'm developing an android application that have daily notification. I have a solution but not enough. My code working after restarting the phone. Users will not restart their devices unless they are required. My notifications will not appear until this time. How can I solve?
BootReceiver.java
public class BootReceiver extends BroadcastReceiver {
private AlarmManager alarmManager;
private PendingIntent pendingIntent;
#Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context, "Device Booted", Toast.LENGTH_SHORT).show();
Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(System.currentTimeMillis());
calendar.set(Calendar.HOUR_OF_DAY, 19);
calendar.set(Calendar.MINUTE, 20);
calendar.set(Calendar.SECOND, 0);
alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
Intent alarmIntent = new Intent(context, AlarmReceiver.class);
pendingIntent = PendingIntent.getBroadcast(context, 1, alarmIntent, 0);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
alarmManager.setExact(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);
}
}
}
Manifest.xml
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<receiver
android:name=".AlarmReceiver" />
<receiver
android:name=".BootReceiver">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED"/>
</intent-filter>
</receiver>
AlarmReceiver.java -> just notification builder

Alarm Manager Android

private void startAlarm() {
AlarmManager alarmMgr;
PendingIntent alarmIntent;
alarmMgr = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(MainActivity.this, AlarmReceiver.class);
alarmIntent = PendingIntent.getBroadcast(MainActivity.this, 0, intent, 0);
Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(System.currentTimeMillis());
calendar.set(Calendar.HOUR_OF_DAY, 23);
calendar.set(Calendar.MINUTE, 52);
alarmMgr.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(),
1000 * 60 * 20, alarmIntent);
}
startAlarm() method is in the MainActivity class.
The following code should display a toast (declared in onReceive() method of the AlarmReceiver class) at 23:52 and every 20 minutes thereafter
AlarmReceiver extends BroadcastReceiver.
The code compiles without errors but for some reason it is not displaying the toast.
NOTE : The code worked fine with ELAPSED_REALTIME_WAKEUP. I am having problem with RTC_WAKEUP only. So everything else has to be correct. There is something wrong inside the startAlarm() method only.

I have tried your code with some modification as below .
private void startAlarm() {
AlarmManager alarmMgr;
PendingIntent alarmIntent;
alarmMgr = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(MainActivity.this, AlarmReceiver.class);
alarmIntent = PendingIntent.getBroadcast(MainActivity.this, 0, intent, 0);
Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(System.currentTimeMillis());
calendar.set(Calendar.HOUR_OF_DAY, 0);
calendar.set(Calendar.MINUTE, 2);
alarmMgr.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(),
1000 * 20, alarmIntent);
}
This code works fine with AlarmManager.RTC_WAKEUP. If it does not work for you, please reboot your device after installing it. After reboot completed, start your app. Then it should fire the alarm and every 20 sec interval the alarm fires repeatedly.
You can also check the difference between RTC_WAKEUP and ELAPSED_REALTIME_WAKEUP. From android docs, elapsedRealtime means, Returns milliseconds since boot, including time spent in sleep and RTC means, time in System.currentTimeMillis() (wall clock time in UTC).

Looks like You need to set an action to the intent:
Intent intent = new Intent(MainActivity.this, AlarmReceiver.class);
intent.setAction("YourPackageName.YourAction");
alarmIntent = PendingIntent.getBroadcast(MainActivity.this, 0, intent, 0);
And in the manifest:
<receiver android:name=".AlarmReciever">
<intent-filter>
<action android:name="YourPackageName.YourAction" />
</intent-filter>
</receiver>
This should fix the issue. You must have a unique action in the intent for use it with broadcast receiver.

how to start B class at every specific time on android?

I want use String start = "16:00"; in specific time, start another activity.
I must use String start = "16:00"
MainActivity.class
String start = "16:00";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setAlarmTime(this);
}
private void setAlarmTime(Context context) {
String[] strStart = start.split(":") // delete ":"
Calendar cal_start = Calendar.getInstance();
cal_start.set(Calendar.HOUR_OF_DAY, Integer.parseInt(strStart[0])); // hour
cal_start.set(Calendar.MINUTE, Integer.parseInt(strStart[1])); //minute
AlarmManager alarm = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(this, AlarmActivity.class);
PendingIntent pIntent = PendingIntent.getActivity(context, 0, intent, 0);
alarm.set(AlarmManager.RTC, cal_start.getTimeInMillis(), pIntent);
}
I want while the app is running, current time 4 o'clock , start AlarmActivity.class .
But it does not work.
How to every specific time start another activity on android?
#update
private void setAlarmTime(Context context) {
String[] strStart = start.split(":");
Calendar cal_start = Calendar.getInstance();
cal_start.set(Calendar.HOUR_OF_DAY, Integer.parseInt(strStart[0]));
cal_start.set(Calendar.MINUTE, Integer.parseInt(strStart[1]));
AlarmManager alarm = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(this, AlarmReceiver.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, 0);
alarm.set(AlarmManager.RTC_WAKEUP, cal_start.getTimeInMillis(), pendingIntent);
this source not work.
not work alarmManager.

Please consider to use AlarmManager.RTC_WAKEUP if you need to wake up the device even if it goes off.
alarm.set(AlarmManager.RTC_WAKEUP, cal_start.getTimeInMillis(), pIntent);
AlarmManager.RTC will NOT wake the device up.
Reference: https://developer.android.com/reference/android/app/AlarmManager.html#RTC
Btw, you do not need to pass the context reference to method:
PendingIntent pIntent = PendingIntent.getActivity(this /*can use this as it is a context already */ , 0, intent, 0);
Update:
Please also set the second and millisecond of the cal_start; otherwise it will be the values that you get the calendar instance.
cal_start.set(Calendar.SECOND, 0);
cal_start.set(Calendar.MILLISECOND, 0);
Update 2:
It works in my side, you may try to add
<uses-permission android:name="android.permission.WAKE_LOCK" />
in Manifests.
Btw, if you want this alarm repeat every day
AlarmManager alarm = (AlarmManager) getSystemService(ALARM_SERVICE);
alarm.setRepeating(AlarmManager.RTC_WAKEUP, cal_start.getTimeInMillis(), AlarmManager.INTERVAL_DAY, pIntent);

Add this permission in your manifest
<uses-permission android:name="android.permission.WAKE_LOCK" />
register your receiver class in the application tag in the manifest file
<receiver android:name=".AlarmActivity" />
Resister your alarm that will trigger AlarmActivity at a specific time in your case its 16:00
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.HOUR_OF_DAY, 16);
calendar.set(Calendar.MINUTE, 0);
calendar.set(Calendar.SECOND, 0);
Intent intent = new Intent(getApplicationContext(), AlarmActivity.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(getApplicationContext(), 100, intent, PendingIntent.FLAG_UPDATE_CURRENT);
AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), AlarmManager.INTERVAL_DAY, pendingIntent);
Make sure your register class extend BroadcastReceiver like this
class AlarmActivity extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
// Do whatever you want
// you can generate notifications here
// or can start your application activity you want
}
}

AlarmManager set method not working when called from boot receiver

I have looked everywhere for this solution most of the replies ask to set alarm in boot receiver.
i have implemented a boot receiver and started a service and set a alarm using set method.
Service is started fine but alarm is not setting.
please help i am stuck on that.
i can post some also if you want but boot receiver is working fine as i am also starting service in that
public class MyReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
SharedPreferences sharedPref = context.getSharedPreferences(
Util.SHARED_PREF_NAME, Context.MODE_PRIVATE);
long curTime = System.currentTimeMillis();
long endTime = sharedPref.getLong(Util.END_TIME, -1);
long startTime = sharedPref.getLong(Util.START_TIME, -1);
if (curTime < endTime && startTime >= curTime) {
Intent intent1 = new Intent(context, HUD.class);
PendingIntent pintent = PendingIntent.getService(context, 1987,
intent1, PendingIntent.FLAG_CANCEL_CURRENT);
AlarmManager alarm = (AlarmManager) context
.getSystemService(Context.ALARM_SERVICE);
alarm.setRepeating(AlarmManager.RTC_WAKEUP, endTime, 100, pintent);
Log.e("alaram set", endTime + " " + curTime);
}
Intent service = new Intent(context, HUD.class);
context.startService(service);
}
}
MyReceiver.java
<receiver
android:name=".MyReceiver"
android:enabled="true"
android:exported="true" >
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
</intent-filter>
</receiver>
Manifest.xml
Service started successfully after boot
but alarm.setRepeating(AlarmManager.RTC_WAKEUP, endTime, 100, pintent);
alarm is not working.
I think i clear my question.
Plz help

Intent intent1 = new Intent(context, HUD.class);
PendingIntent pintent = PendingIntent.getService(context, 1987,
intent1, PendingIntent.FLAG_CANCEL_CURRENT);
AlarmManager alarm = (AlarmManager) context
.getSystemService(Context.ALARM_SERVICE);
Calendar cal = Calendar.getInstance();
cal.add(Calendar.SECOND, 30);
alarm.setInexactRepeating(AlarmManager.RTC_WAKEUP,
cal.getTimeInMillis(), 100, pending);
Try your setInexactRepeating instead of setRepeating that is more performance optimized method.