Q:

Have a job run at certain time of day, everyday with Evernote's android-job

Is their a pattern for having Evernote's android-job run a job at between 1AM and 2AM everyday?
I was thinking it might make sense to do something like having in my Application.onCreate and at the end of my Job.onRunJob
// use the current time to see how long it will be until 1AM
long timeUntil1Am = getTimeUntil1Am(currentUnixTimeStamp);

new JobRequest.Builder(DemoSyncJob.TAG)
            .setExecutionWindow(timeUntil1Am, timeUntil1Am + 3600_000L)
            .setBackoffCriteria(5_000L, JobRequest.BackoffPolicy.EXPONENTIAL)
            .setRequiresCharging(true)
            .setRequiresDeviceIdle(false)
            .setRequiredNetworkType(JobRequest.NetworkType.CONNECTED)
            .setRequirementsEnforced(true)
            .setPersisted(true)
            .setUpdateCurrent(true)
            .build()
            .schedule();

which would run the job the first time at ~1AM from the application on create and then use the onRunJob to daisy chain the next run time.
I think this would work, but I am concerned that the job would be scheduled multiple times because a new job is created every time the Application is built. If I knew the job was already scheduled I could avoid this, but not sure if that is possible.
So my question is using this daisy chain a reasonable pattern and how do I avoid running the job more than once per day?

A:

I used something similar to the pattern in the FAQ mentioned by @CommonsWare
To make this easier i created a wrapper class to get a daily execution window
Class to get start and endtime relative to current time
class DailyExecutionWindow {
    final long startMs;
    final long endMs;

    /**
     * Holds the start end time in ms for a job.
     * Will wrap around to next day if currentHour < targetHour.
     * If the current time is exactly now it will be forced to 60 seconds in the future.
     *
     * @param currentHour - current currentHour
     * @param currentMinute - current currentMinute
     * @param targetHour - currentHour we want to start
     * @param targetMinute - currentMinute we want to start
     * @param windowLengthInMinutes - number of minutes for the execution window
     */
    DailyExecutionWindow(int currentHour, int currentMinute, long targetHour, long targetMinute, long windowLengthInMinutes) {
        long hourOffset;
        long minuteOffset;

        if (targetHour == currentHour && targetMinute < currentMinute) {
            hourOffset = TimeUnit.HOURS.toMillis(23);
        } else if (targetHour - currentHour == 1) { // if we are less then an hour ahead, but into the next hour
            // move forward to 0 minute of next hour
            hourOffset = TimeUnit.MINUTES.toMillis(60 - currentMinute);
            currentMinute = 0;
        } else if (targetHour >= currentHour) {
            hourOffset = TimeUnit.HOURS.toMillis(targetHour - currentHour);
        } else {
            hourOffset = TimeUnit.HOURS.toMillis((24 + targetHour) - currentHour);
        }

        if (targetMinute >= currentMinute) {
            minuteOffset = TimeUnit.MINUTES.toMillis(targetMinute - currentMinute);
        } else {
            minuteOffset = TimeUnit.MINUTES.toMillis((60 + targetMinute) - currentMinute);
        }

        this.startMs = Math.max(hourOffset + minuteOffset, 60000);
        this.endMs = this.startMs + TimeUnit.MINUTES.toMillis(windowLengthInMinutes);

    }
}

My chaining Job implementation
public class UpdateFeedsJob extends Job {

    public static final String TAG = UpdateFeedsJob.class.getName();
    private static final long TARGET_HOUR = 2L;
    private static final long TARGET_MINUTE = 15;
    private static final long WINDOW_LENGTH = 60;
    private static final int WAKE_LOCK_AWAIT_TIME_SECONDS = 60;

    // called in <MyApplication extends Application>.onCreate()
    public static void schedule() {
        schedule(true);
    }

    private static void schedule(boolean updateCurrent) {
        Calendar calendar = Calendar.getInstance();
        int hour = calendar.get(Calendar.HOUR_OF_DAY);
        int minute = calendar.get(Calendar.MINUTE);

        DailyExecutionWindow executionWindow =
                new DailyExecutionWindow(hour, minute, TARGET_HOUR, TARGET_MINUTE, WINDOW_LENGTH);

        new JobRequest.Builder(UpdateFeedsJob.TAG)
                .setExecutionWindow(executionWindow.startMs, executionWindow.endMs)
                .setPersisted(true)
                .setUpdateCurrent(updateCurrent)
                .build()
                .schedule();
    }

    @NonNull
    @Override
    protected Result onRunJob(Params params) {
        try {
            // ... do work
            return Result.SUCCESS;
        } finally {
            schedule(false);
        }
        return Result.FAILURE;
    }
}

You can see a working example in my Podcast Player Application on github

