AlarmHelper that helps scheduling repeating non-wakeup inexact alarms. Define how to create the pending intent (e.g. getBroadcast vs getService), the alarm interval, and the first delay.

AlarmHelper.java

package com.example;

import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.SystemClock;
import android.util.Log;

/**
 * Example: schedule about twice a day, and wait at least 10 minutes before the first alarm
 *
 * AlarmHelper myServiceAlarmHelper = new AlarmHelper(context, AlarmManager.INTERVAL_HALF_DAY, 1000 * 60 * 10) {
 *     @Override
 *     protected PendingIntent pendingIntent(Context context, int flags) {
 *         Intent intent = new Intent(context, MyService.class).putExtra("foo", "bar");
 *         return PendingIntent.getService(context, 0, intent, flags);
 *     }
 * };
 * myServiceAlarmHelper.scheduleIfMissing();
 */
public abstract class AlarmHelper {
    private final Context context;
    private final long inexactAlarmIntervalMs;
    private final long firstAlarmMinDelayMs;

    public AlarmHelper(Context context, long inexactAlarmIntervalMs, long firstAlarmMinDelayMs) {
        this.context = context.getApplicationContext();
        this.inexactAlarmIntervalMs = inexactAlarmIntervalMs;
        this.firstAlarmMinDelayMs = firstAlarmMinDelayMs;
    }

    /**
     * Schedule the alarm only if it hasn't been scheduled yet. To be used on every app start, e.g. in the onCreate() method
     * of the Application subclass.
     *
     * Even if this is called after the app stopped or crashed, it won't overwrite the previously-scheduled alarm.
     */
    public void scheduleIfMissing() {
        if (pendingIntent(context, PendingIntent.FLAG_NO_CREATE)) != null) {
            // Assume that finding the intent means the alarm has been scheduled.
            Log.d("AlarmHelper", "Found pending intent, not scheduling the alarm");
        } else {
            Log.d("AlarmHelper", "Didn't find the pending intent, scheduling the alarm");
            scheduleUnconditionally();
        }
    }

    /**
     * Schedule the alarm unconditionally. To be used after boot.
     */
    public void scheduleUnconditionally() {
        Log.d("AlarmHelper", "called");
        PendingIntent pendingIntent = pendingIntent(context, PendingIntent.FLAG_UPDATE_CURRENT);

        // Check approximately every alarm interval, don't wake the device up, wait initially for at least firstAlarmMinDelayMs
        AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
        alarmManager.setInexactRepeating(AlarmManager.ELAPSED_REALTIME,
                                         SystemClock.elapsedRealtime() + firstAlarmMinDelayMs,
                                         inexactAlarmIntervalMs,
                                         pendingIntent);
    }

    protected abstract PendingIntent pendingIntent(Context context, int flags);
}