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Scheduling A Periodic Background Job Using Android Work Manager

by Jai KherajaniFebruary 4th, 2021

Too Long; Didn't Read

Here we explain how to use Work Manager in Android to schedule a synchronized periodic background job.

featured image - Scheduling A Periodic Background Job Using Android Work Manager

🎯 Objective

We will perform a very simple task of printing a number in the logs every 15 minutes with the help of Work Manager.

🤔 What is Work Manager?

Work Manager is a simple library for doing any deferrable background work reliably. Here, a background task which doesn't needs to be executed at an exact moment is considered to be deferrable and by reliably I mean that the task should be executed even if the user exits the app or the device restarts.

👨🏽‍💻 Let's code

⚠️ Pre-requisites

1. Create an android project with an Empty activity. Select Launcher Activity and Generate layout file options.

2. Verify you have

google()

in Project level

build.gradle

file. If not please add it. The result should look as below :

allprojects {
    repositories {
        google()

        // If you're using a version of Gradle lower than 4.1, you must instead use:
        // maven {
        //     url 'https://maven.google.com'
        // }
        // An alternative URL is 'https://dl.google.com/dl/android/maven2/'
    }
}

👉🏼 Import library

In Module level

build.gradle

file paste the following the line of code :

implementation "androidx.work:work-runtime:2.5.0"

For latest available version of this library, please refer this page.

👉🏼 Create a Worker class

1. Create a new class

MyWorker

and it should extend

Worker

2. Create a parameterized constructor :

public MyWorker(@NonNull Context context, @NonNull WorkerParameters workerParams) {
        super(context, workerParams);
    }

3. Override and implement the

doWork()

method :

@NonNull
    @Override
    public Result doWork() {
        return null;
    }

4. Create a new static integer variable called count.

5. Inside the

doWork()

, increase value of count and also print the value in log :

count++;
Log.d("MyWorker","worker called - "+count+" time(s)");

💡
doWork()
is the method where we need to perform the actual background task, this method gets executed on a background thread. It is good for doing Synchronous tasks. For asynchronous task I will write another tutorial.

6. Return

Result.success()

We've written our worker class and the final class should look similar to :

public class MyWorker extends Worker {

    private static int count = 0;

    public MyWorker(@NonNull Context context, @NonNull WorkerParameters workerParams) {
        super(context, workerParams);
    }

    @NonNull
    @Override
    public Result doWork() {
        count++;
        Log.d("MyWorker", "worker called - " + count + " time(s)");
        return Result.success();
    }
}

👉🏼 Create UI

activity_main.xml

create a Button inside the

LinearLayout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    tools:context=".MainActivity"
    android:layout_margin="16dp">

    <Button
        android:id="@+id/trigger_job"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="Trigger Job" />

</LinearLayout>

👉🏼 Start worker on button press

1. In

MainActivity

, create a Button type variable and map it to xml button using

findViewById()

Button scheduleJob = findViewById(R.id.trigger_job);

2. Set a new

onClickListener()

on button :

scheduleJob.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

            }
        });

3. Inside the onClickListener(), assuming that we don't want to run this job when battery is low, create Constraints for the job :

Constraints constraints = new Constraints.Builder()
                        .setRequiresBatteryNotLow(true)
                        .build();

💡 Constraints as the name implies are set of conditions that must be satisfied for the job to execute. For more details please refer this link.

4. Create a periodic work request, we need to specify our worker class, time and its unit in which our task will be execute at least once as long as the constraints are satisfied.

PeriodicWorkRequest periodicWorkRequest = new PeriodicWorkRequest.Builder(MyWorker.class, 15, TimeUnit.MINUTES)
                        .setConstraints(constraints)
                        .build();

5. Enqueue this periodic work request. We need to provide a unique name to be used by this worker, whether to replace or keep the pending (uncompleted) request, and

periodicWorkRequest

object that we have created previously. We'll display a toast on the screen to notify user that work has been scheduled.

WorkManager workManager = WorkManager.getInstance(getApplicationContext());
                workManager.enqueueUniquePeriodicWork("Counter", ExistingPeriodicWorkPolicy.KEEP,periodicWorkRequest);
                Toast.makeText(MainActivity.this, "🎉 Scheduled job!", Toast.LENGTH_SHORT).show();

The

MainActivity

class will look similar to this :

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button scheduleJob = findViewById(R.id.trigger_job);
        scheduleJob.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Constraints constraints = new Constraints.Builder()
                        .setRequiresBatteryNotLow(true)
                        .build();

                PeriodicWorkRequest periodicWorkRequest = new PeriodicWorkRequest.Builder(MyWorker.class, 15, TimeUnit.MINUTES)
                        .setConstraints(constraints)
                        .build();

                WorkManager workManager = WorkManager.getInstance(getApplicationContext());
                workManager.enqueueUniquePeriodicWork("Counter", ExistingPeriodicWorkPolicy.KEEP,periodicWorkRequest);
                Toast.makeText(MainActivity.this, "🎉 Scheduled job!", Toast.LENGTH_LONG).show();
            }
        });
    }
}