Question

I’ve created an Started Service from an activity. I’m curious about: what happens if the activity gets destroyed? Does the service still run? (I think it runs!)

Then when the activity is re-created, is there any way to communicate with that service? I just need to know whether the service is still running, if running, then I want to pass a reference of the activity to the service.

Answer 1

Okay, a comment isn’t big enough. Here’s some code I use to start a service. Following the start service is a function I use to determine if the service is running. The class DownloadDatabase extends IntentService. The service downloads a 70 megabyte SQLite database that was created externally to Android.

 Intent intentService = new Intent(this, DownloadDatabase.class);
 startService(intentService);

The following function checks to see if the service is already running. It is coded as a function because I call it from other routines that do other verifications if is not running.

private boolean isMyServiceRunning() {
    ActivityManager manager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
    for (RunningServiceInfo service : manager
            .getRunningServices(Integer.MAX_VALUE)) {
        if ("com.hodsonssoftwarellc.nutritionexplorer.DownloadDatabase"
                .equals(service.service.getClassName())) {
            return true;
        }
    }
    return false;
}

You will also need the following permission in your manifest:

 uses-permission android:name="android.permission.GET_TASKS"

What is happening in the isMyServiceRunning function is as follows:

1. The Activity Manager is acquired.
2. A list of tasks that are currently running is retrieved and used as the argument in the special case for loop.
3. As each task is retrieved from the list, the task name is compared to my fully qualified class name for the download service.
4. If a match is found, the function returns true. Otherwise it returns false.

So, in answer to your question, yes, you can check to see if it running from your task that starts it. Even if you exit the task and start it again. You can also check if is running from a different activity or app.

Note: This code was written for 2.x compatibility. If you are doing a download in version 3 or higher, use the download manager instead of writing your own download service.