Get application context from non activity singleton class

Question

In my android project, I have ImageAdapter class in which I pass app context for some further needs.

public class ImageAdapter extends BaseAdapter {
    priv         


        

Answer 1

APPROACH #1:

Since you specify that ImageAdapter is a singleton, one simple answer is to create that singleton from a class that has access to app context:

public class MyApplication extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        ImageAdapter.createIt(this);
    }
}

public class ImageAdapter extends BaseAdapter {
    private static ImageAdapter it;
    // Get the singleton.
    public static ImageAdapter getIt() {
        return it;
    }
    // Call this once, to create the singleton.
    public static void createIt(Context context) {
        it = new ImageAdapter(context);
    }

    private final Context c;
    private ImageAdapter(Context context) {
        c = context;
    }
}

---

APPROACH #2:

If it were not a singleton, then I would use the accepted answer. In that case, remove the local variable from ImageAdapter, because context can always be obtained from MyApplication. Expanding on the accepted answer, if you want a local method as a convenience, define ImageAdapter.getContext(). Complete solution:

public class MyApplication extends Application {
    private static Context appContext;
    public static Context getContext() {
        return appContext;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        appContext = this;
    }
}

public class ImageAdapter extends BaseAdapter {
    public ImageAdapter() {
    }

    // [Optional] Call this whenever you want the app context.
    private Context getContext() {
        return MyApplication.getContext();
    }
}