AlarmManager not canceling

Question

Hello I am new to android and I am trying to make an app that will check battery status when device is charging . if battery level is more than defined in setting than it will show a notification and will also ring .

I am now just testing it and showing notification after every 30 second after device is plugged in . according my logic alarm manger will set when device is plugged in and will cancel pending of alarm manager when device is plugged out.

But it is not working, notification is also showing after disconnecting device . I don't know why it is happening . I have tried to cancel pending but it is not working.

please help me what is going on here.

CustomReceiver

public class CustomReceiver extends BroadcastReceiver {

    AlarmManager alarmManager;
    PendingIntent p;

    @Override
    public void onReceive(Context context, Intent intent) {
        String intentAction = intent.getAction();
        if (intentAction != null) {
            if (intentAction.equals(Intent.ACTION_POWER_CONNECTED)) {
                toast("Power Connected", context);
                setBatteryAlarm(context);
            }
            if (intentAction.equals(Intent.ACTION_POWER_DISCONNECTED)) {
                toast("Power Disconneted", context);
                cancelAlarm();
            }
        }
    }


    public void toast(String msg, Context context) {
        Toast.makeText(context, msg, Toast.LENGTH_SHORT).show();
    }

    private void setBatteryAlarm(Context context) {
        Intent notifyIntent = new Intent(context, BatteryCheckingReciever.class);
        p = PendingIntent.getBroadcast(context, 0, notifyIntent, PendingIntent.FLAG_UPDATE_CURRENT);

        long repeatInterval = 30000;
        long triggerTime = SystemClock.elapsedRealtime() + repeatInterval;

        alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
        alarmManager.setInexactRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, triggerTime, repeatInterval, p);
    }

    private void cancelAlarm() {
        Log.e("kiran", "canceling alarm");
        if (alarmManager != null) {
            alarmManager.cancel(p);
            alarmManager = null;
        }
    }
}

BroadCast reciever for notification

public class BatteryCheckingReciever extends BroadcastReceiver {

    NotificationManager notificationManager;
    int NOTIFICATION_ID = 0;
    String PRIMARY_CHANNEL = "battery_is_full";

    @Override
    public void onReceive(Context context, Intent intent) {

        showNotificaiton(context);
    }

    private void showNotificaiton(Context context) {
        notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);

        NotificationCompat.Builder builder = new NotificationCompat.Builder(context, PRIMARY_CHANNEL)
                .setSmallIcon(R.drawable.ic_battery_full)
                .setContentTitle(context.getString(R.string.battery_full))
                .setContentText(context.getString(R.string.battery_full_text))
                .setPriority(NotificationCompat.PRIORITY_HIGH)
                .setAutoCancel(true)
                .setDefaults(NotificationCompat.DEFAULT_ALL);

        notificationManager.notify(NOTIFICATION_ID, builder.build());
    }
}

manifest file

<application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <receiver
            android:name=".BatteryCheckingReciever"
            android:enabled="true"
            android:exported="true"></receiver>
        <receiver
            android:name=".CustomReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.ACTION_POWER_CONNECTED" />
                <action android:name="android.intent.action.ACTION_POWER_DISCONNECTED" />
            </intent-filter>
        </receiver>

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <action android:name="android.intent.action.VIEW" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

sorry for bad English .

Answer 1

it is because your reference for alarm manager and pending intent change. Most probably your alarm manager becomes null but because you are making null check you dont have error. You need to reference same objects again

Change your code like this:

  private void cancelAlarm() {

 alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
Intent notifyIntent = new Intent(context, BatteryCheckingReciever.class);
 p = PendingIntent.getBroadcast(context, 0, notifyIntent, PendingIntent.FLAG_UPDATE_CURRENT);


        if (alarmManager != null) {
       Log.e("kiran", "canceling alarm");
            alarmManager.cancel(p);
            alarmManager = null;
        }
    }

https://stackoverflow.com/a/4350149/11982611