Unit 7 Pathway 1 Activity 5: Practice: Build Water Me app¶

Before you begin¶

Introduction¶

  • In this unit, you learned about WorkManager, which is a Jetpack library for deferrable background work. This background work is guaranteed to run even if you close its source app.

  • While learning about WorkManager, you learned how to define work in a Worker class, how to create a WorkRequest for the Worker, and how to enqueue and schedule work.

  • In this practice set, you take the concepts you learned and enhance the Water Me! app.

  • The solution code is available at the end. To make the most of this learning experience, try to implement and troubleshoot as much as you can before looking at the provided solution code. It is during this hands-on time that you learn the most.

Prerequisites¶

  • Android Basics with Compose coursework through the Advanced WorkManager and Testing codelab

What you’ll need¶

  • A computer with internet access and Android Studio

What you’ll build¶

  • In this practice set, you take the concepts you learned and enhance the Water Me! app.

  • The app currently displays a list of plants in a scrolling list. When you tap on a plant, the app lets you set a reminder to water the plant.

    ../_images/unit7-pathway1-activity5-section1-fb69d6519999f217_1440.png
    ../_images/unit7-pathway1-activity5-section1-d6b68d1e9f1026c5_1440.png

  • While you can select a reminder timeframe, the reminder notification doesn’t display.

  • Your job is to implement the background work for the reminder notification to display.

  • After you complete your code, the app can then display a reminder notification after a selected time duration elapses.

    ../_images/unit7-pathway1-activity5-section1-a8f9bceed83af5a9_1440.png

Get the starter code¶

Schedule notification using WorkManager¶

  • The functionality for the Water Me! app is mostly implemented except for the ability to schedule the reminder notification.

  • The code to make a notification is in the WaterReminderWorker.kt file, which is in the worker package. The WaterReminderWorker class extends the CoroutineWorker class, and the code to make the notification is inside its doWork() method.

  • This code is already complete, no changes needed.

    override suspend fun doWork(): Result {

    val plantName = inputData.getString(nameKey)

    makePlantReminderNotification(
        applicationContext.resources.getString(R.string.time_to_water, plantName),
        applicationContext
    )

    return Result.success()
}

    Important

    Enable notifications on the app (long-press the app icon, App info, allow notifications), otherwise the notifications will not appear.

  • Your task is to create a OneTimeWorkRequest that calls this method with the correct parameters from the WorkManagerWaterRepository.

Create work requests¶

  • To schedule the notification, you need to implement the scheduleReminder() method in the WorkManagerWaterRepository.kt file.

    // Add this to class WorkManagerWaterRepository
override fun scheduleReminder(duration: Long, unit: TimeUnit, plantName: String) {

}

  • Create a variable called data with Data.Builder. The data needs to consist of a single string value where WaterReminderWorker.nameKey is the key and the plantName passed into scheduleReminder() is the value.

    solulu
    override fun scheduleReminder(duration: Long, unit: TimeUnit, plantName: String) {

    val data = Data.Builder()
    data.putString(WaterReminderWorker.nameKey, plantName)

}

  • Create a one-time work request with the WaterReminderWorker class. Use the duration and unit passed into the scheduleReminder() function and set the input data to the data variable you create.

    solulu
    override fun scheduleReminder(duration: Long, unit: TimeUnit, plantName: String) {

    val data = Data.Builder()
    data.putString(WaterReminderWorker.nameKey, plantName)

    val workRequestBuilder = OneTimeWorkRequestBuilder<WaterReminderWorker>()
        .setInitialDelay(duration, unit)
        .setInputData(data.build())
        .build()

}

  • Call the workManager’s enqueueUniqueWork() method. Pass in:

    • the plant name concatenated with the duration

    • ExistingWorkPolicy.REPLACE

    • the workRequestBuilder object

    solulu
    override fun scheduleReminder(duration: Long, unit: TimeUnit, plantName: String) {

    val data = Data.Builder()
    data.putString(WaterReminderWorker.nameKey, plantName)

    val workRequestBuilder = OneTimeWorkRequestBuilder<WaterReminderWorker>()
        .setInitialDelay(duration, unit)
        .setInputData(data.build())
        .build()

    workManager.enqueueUniqueWork(
        plantName + duration,
        ExistingWorkPolicy.REPLACE,
        workRequestBuilder
    )

}

    Note

    Passing in the plant name, concatenated with the duration, lets you set multiple reminders per plant. You can schedule one reminder in 5 seconds for a Peony and another reminder in 1 day for a Peony. If you only pass in the plant name, when you schedule the second reminder for a Peony, it replaces the previously scheduled reminder for the Peony.

  • Your app should now work as expected.

Solution code¶