A helper class to show strings from strings.xml in presenters which can be mocked later in tests

StringHelper.java

public final class StringHelper {
    private Context mContext;
    @SuppressLint("StaticFieldLeak")
    private static StringHelper sInstance;

    private StringHelper(Context context) {
        this.mContext = context;
    }

    public static void init(Context context) {
        if (sInstance == null) {
            sInstance = new StringHelper(context.getApplicationContext());
        }
    }

    public static StringHelper getInstance() {
        if (sInstance == null) {
            throw new IllegalStateException("Initialize instance before getting instance");
        }
        return sInstance;
    }

    public String getString(@StringRes int value) {
        return mContext.getString(value);
    }
}