Is a “concrete function” over “generic function” a good implementation?

Question

I want to know others opinion about this approach that I use in a lot of projects, for example, I can show the last time that I use it:

public class DataStorageService {
    private enum Keys {
        USER_NAME("userName"), USER_ID("userId"), TELEPHONE("telephone"), EMAIL("email");

        private final String key;

        Keys(String key){
            this.key = key;
        }

        public String getKey(){
            return key;
        }

    }

    private SharedPreferences sharedPreferences;

    public DataStorageService(Context context){
        sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
    }

    public void clearUserData(){
        setTelephone("");
        setUserEmail("");
        setUserName("");
    }

    public String getUserId(){
        return getString(Keys.USER_ID, "");
    }

    public void setUserId(String userName){
        putString(Keys.USER_ID, userName);
    }

    public String getUserName(){
        return getString(Keys.USER_NAME, "");
    }

    public void setUserName(String userName){
        putString(Keys.USER_NAME, userName);
    }

    public String getUserEmail(){
        return getString(Keys.EMAIL, "");
    }

    public void setUserEmail(String email){
        putString(Keys.EMAIL, email);
    }

    public String getTelephone(){
        return getString(Keys.TELEPHONE, "");
    }

    public void setTelephone(String telephone){
        putString(Keys.TELEPHONE, telephone);
    }

    private String getString(Keys key, String defaultValue){
        return getSharedPreferences().getString(key.getKey(), defaultValue);
    }

    private void putString(Keys key, String value){
        SharedPreferences.Editor editor = getSharedPreferences().edit();
        editor.putString(key.getKey(), value);
        editor.apply();
    }

    private Boolean getBoolean(Keys key, Boolean defaultValue){
        return getSharedPreferences().getBoolean(key.getKey(), defaultValue);
    }

    private void putBoolean(Keys key, Boolean value){
        SharedPreferences.Editor editor = getSharedPreferences().edit();
        editor.putBoolean(key.getKey(), value);
        editor.apply();
    }

    private SharedPreferences getSharedPreferences(){
        return  sharedPreferences;
    }

}

How you can see, I have a "generic method" (putBoolen, getBoolean, putString, getString) to get a data of SharedPreferences, these methods are private because I do not want to be able the possibility of access to SharedPreferences (with this class). Then I create a new class for get access to concretes cases how telephone, userId, etc...

Is this approach a good approach os is better to put only the putBolean, getBoolean etc...?

With another example:

public class ActivityOpenerService {

    private Context context;

    public ActivityOpenerService(Context context){
        setContext(context);
    }

    private Context getContext(){
        return context;
    }

    public void launchAboutActivity(){
        launch(AboutActivity.class);
    }

    public void launchAssistanceFinishedActivity(){
        launch(AssistanceFinishedActivity.class);
    }

    public void launchLoginActivity(){
        launch(LoginActivity.class);
    }

    public void launchRegisterActivity(){
        launch(RegisterActivity.class);
    }

    public void launchProfileActivity(){
        launch(ProfileActivity.class);
    }

    private void launch(Class<? extends Activity> activityToLaunch){
        Intent intent = new Intent(getContext(), activityToLaunch);
        getContext().startActivity(intent);
    }

    public void setContext(Context context){
        this.context = context;
    }

}

Here you can see the same approach, here my "generic function" is launch, and I created another function for concrete cases.

The question is, what do you think about that, is a good approach, or is better call the generic functions in other places instead of concrete functions.

Answer 1

Short answer: yes, it is a good approach in most cases. It has a well-known name, it is called creating abstractions, and it is one of the fundamental basics of program design.

In this case, a class like DataStorageService provides functions with meaningful, specific names for certain actions, hiding away the implementation in terms of functions with unspecific names like putString or getString. This leads to a clear, easy-to-grasp API for a user of that class.