Get application context from non activity singleton class

Update: 06-Mar-18

Use MyApplication instance instead of Context instance. Application instance is a singleton context instance itself.

public class MyApplication extends Application {    private static MyApplication mContext;    @Override    public void onCreate() {        super.onCreate();        mContext = this;    }    public static MyApplication getContext() {        return mContext;    }}

Previous Answer

You can get the the application context like this:

public class MyApplication extends Application {    private static Context mContext;    @Override    public void onCreate() {        super.onCreate();        mContext = getApplicationContext();    }    public static Context getContext() {        return mContext;    }}

Then, you can call the application context from the method MyApplication.getContext()

Don't forget to declare the application in your manifest file:

<application    android:name=".MyApplication"    android:icon="@drawable/icon"    android:label="@string/app_name" >

I'd rather pass a context instance as a parameter to every method in singleton which really needs it

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();    }}