Singleton with context as a variable - memory leaks?

Question

I am building a class to handle an app shared preferences. I want to make it singleton accessed from all parts of the project. I can't use the regular getInstance method as I need to pass a context for the class to be functional. I thought of passing a context in the MainActivity.java and than have it constantly there. Will there be memory leaks?

This is my current solution:

public class LocalStorage {

    private Context context;

    private static LocalStorage instance = null;

    protected LocalStorage() {
        // Exists only to defeat instantiation.
    }

    public static LocalStorage getInstance() {
        if(instance == null) {
            instance = new LocalStorage();
        }
        return instance;
    }

    public static LocalStorage getInstance(Context _context) {
        LocalStorage localStorage = getInstance();
        localStorage.context = _context.getApplicationContext();
        return localStorage;
    }

    private SharedPreferences sharedPreferences() {
        return context.getSharedPreferences("mySettings", Context.MODE_PRIVATE);
    }
 ....

Answer 1

You will not create a leak since you are only keeping a reference to the application context by calling getApplicationContext().

If you referenced _context directly and that reference happened to be an Activity or some other Context then yes you would have created a memory leak.

As a side note the implementation of the Singleton here is a bit odd. I would suggest the following to remove the unnecessary extra getInstance() by passing in the Context to the constructor:

public class LocalStorage {
    private static LocalStorage instance = null;

    private Context context;

    private LocalStorage(Context context) {
        this.context = context;
    }

    public synchronized static LocalStorage getInstance(Context context) {
        if(instance == null) {
            instance = new LocalStorage(context.getApplicationContext());
        }

        return instance;
    }

    private SharedPreferences sharedPreferences() {
        return context.getSharedPreferences("mySettings", Context.MODE_PRIVATE);
    }
    ....