CODEWITHSUNDEEP
androidmultithreadinggps
Nebril
Nebril

Reputation: 3273

Android multi thread application - sharing state

I am working on Android application that has several threads - one of them is getting data from GPS receiver 1 time per second. I would like other threads to have access to information from the GPS thread.

I already tried doing it with message queues, but it made the code quite messy - all new threads I created had to handle messages in it's own way, so I had to do a lot of new implementation in every thread class.

I would like to be able to simply get the data in this manner:

ApplicationState.getLocation();

so I can use the most recent data. How can I accomplish it? I don't want to create static class with synchronized fields because I don't want to lock the threads for too long because I am doing some online image analysis in other thread.

What approach would be the best here?

Cheers, Nebril

Upvotes: 2

Views: 487

Answers (2)

Chris Horner
Chris Horner

Reputation: 2004

Have you considered using an Event Bus system? Otto, an Apache licensed library from Square is pretty neat.

You could create a location updating class that fires new LocationUpdateEvents. Any objects interested in receiving this update can have a method annotated with @Subscribe. It's sweet method for interprocess communication that doesn't rely on messy listener interfaces.

Another advantage of Otto is that your LocationUpdater class could have a method annotated with @Produce. With this, any object that begins listening for LocationUpdateEvents will receive one immediately with the last location found by your LocationUpdater.

Upvotes: 3

gezdy
gezdy

Reputation: 3322

1)create your application class "MyApp" :

1.1)in the manifest file:

<application
    android:name=".MyApp"
    ....
/>

1.2)create the class:

public class MyApp extends Application {
    public void onCreate() {
          super.onCreate();
    }

    private volatile Location mLastLocation = null;
    public Location getLastLocation(){
        return mLastLocation;
    }
    public void setLastLocation(Location mLastLocation){
        this.mLastLocation = mLastLocation;
    }
}

2)to set the location from any context in your application (services, any activities) in the same process (be careful to have one process. You can have 1 process and multi thread in android) :

((MyApp)context.getApplicationContext()).setLastLocation(location);

3)to get the latest location from any context in your application in the same process:

((MyApp)context.getApplicationContext()).getLastLocation();

NB: you can also use listeners for better performance. Register in a list in MyApp listeners and trigger the listeners from onLocationChanged

Upvotes: 1

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