How to create a job with WorkManager when device is plugged in?

Question

I want to create a job that will be triggered when the device is plugged in, just like broadcast receiver for ACTION_POWER_CONNECTED.

Here is the worker class:

public class ChargerWorker extends Worker {

/* Constants */
    private static final String TAG = "ChargerWorker";
    private static final long TRIGGER_AGE = TimeUnit.MINUTES.toMillis(30);       // At least 30 min old.

    @NonNull
    @Override
    public Result doWork() {
        Log.e(TAG, "Power connection worker of Indoor/Outdoor lib.");
        IndoorOutdoorLogger.v(TAG, "Power connection worker of Indoor/Outdoor lib.");
        Context context = getApplicationContext();

        if (Conditions.isBatteryChargingOnAC(context)) {
            IndoorOutdoorLogger.d(context, TAG, "Power plugged and connected to AC.");
            Log.e(TAG, "Power plugged and connected to AC.");

            if (WiFiConnection.isWifiConnected(context) && WiFiConnection.isCurrentNetworkIndoorRecognized(context)) {
                // In this case an "upgrade" to the confidence level is possible.
                // Only run when the last known detection is old enough.
                DetectionResult latestResult = DetectionResult.loadFromCache(context);
                if (!latestResult.isTimestampValid(TRIGGER_AGE)) {
                    IndoorOutdoorLogger.d(context, TAG, "AC power while connected to a recognized WiFi network, and last detection is old enough, starting detection.");
                    IndoorOutdoorClient client = new IndoorOutdoorClient(context, null);
                    client.startShortDetection(Trigger.POWER);
                }
            }
        }
        return Result.SUCCESS;
    } }

This is how I initialize the work in my onCreate() method:

Constraints constraints = new Constraints.Builder().setRequiresCharging(true).build();
        OneTimeWorkRequest simpleReuquest = new OneTimeWorkRequest.Builder(ChargerWorker.class)
                .setConstraints(constraints)
                .build();
        WorkManager.getInstance().enqueue(simpleReuquest);

When I connect the device to the adapter for the first time, everything works as it should. However when I disconnect the device, and try again, I never reach the doWork function again. Instead I see the following message in the logcat:

E/WorkerWrapper: Status for 031e39f1-bc10-4a35-9341-11453fc0ca21 is SUCCEEDED; not doing any work.

Is it because I use OneTimeWorkRequest? If so how can I schedule it to run every time the device is connected to a power source?

Answer 1

This is because you use OnTimeWorkRequest, from its name you can infer that the request is valid for one time only. Once triggered, it won't be called again, not unless you euqueue it again.
Problem is WorkManager doesn't support any other requests or constraints that are relevant to your need. Take a look at this question.

If you really want to use this Pattern of WorkManger and Requests, i can give you an idea, that relies on the fact that people tend to charge their phone for more than few minutes every time.

You can use a 2 types of WorkRequests combined:

• OneTimeWorkRequest that is the actual logic of your algorithm. Set the constraints to be only when charging.
  Once triggered, this worker will enqueue a PeriodicWorkRequest without any constraints and "The minimum repeat interval that can be defined is 15 minutes"

• PeriodicWorkRequest that that will be triggered every 15 minutes and periodically check if the phone is still charging.
  The first time the worker detect that the device is unplugged, it enqueues the OneTimeWorkRequest from above and cancels itself.

This way you won't detect rapid changes of device power states, but it's the best possible in Android Oreo (and above) since apps that target the API level 26 or higher can no longer register broadcast receivers for implicit broadcasts in their manifest

To check whether your device is plugged or not:

You can even detect what kind of charging it is, use this code:

IntentFilter ifilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
Intent batteryStatus = context.registerReceiver(null, ifilter);

// Are we charging / charged?
int status = batteryStatus.getIntExtra(BatteryManager.EXTRA_STATUS, -1);
boolean isCharging = status == BatteryManager.BATTERY_STATUS_CHARGING ||
                 status == BatteryManager.BATTERY_STATUS_FULL;

// How are we charging?
int chargePlug = batteryStatus.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1);
boolean usbCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_USB;
boolean acCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_AC;

taken right from android developer guide

To cancel a WorkRequest:

First, build it with a tag:

OneTimeWorkRequest.Builder(MyWorker.class)
            .setConstraints(myConstraints)
            .addTag(tag)
            .build();

and then do WorkManager.getInstance().cancelAllWorkByTag(tag)

Another option is to enqueue a unique work:

WorkManager.getInstance().enqueueUniquePeriodicWork(
            uniqueWorkName, ExistingPeriodicWorkPolicy.REPLACE, periodicWork);

and then cancel it with WorkManager.getInstance().cancelUniqueWork(workName)

Answer 2

You Should to use PeriodicWorkRequest that let your Work manager work many time on Time you Choose Fays Minutes Hours as you want