CODEWITHSUNDEEP
c#androidsingleton
innomotion media
innomotion media

Reputation: 922

C#, Android: Delete Singleton

I am working on a project with a lot of account management going on. Unfortunately, the guy who set all of this up is on vacation and something here needs to be done, but I cant really seem to understand what exactly is going on here ( I am kind of new to this...)

So basically, as far as I understand: When someone logs into our app, a singleton account is created. There are two classes that matter here:

namespace Accounts
{
    //Generische und Lazy Singleton-Abstraktion
    public abstract class AbstractAccount<T> where T : class
    {
        // Lazy Instanziierung
        private static readonly Lazy<T> _instance = new Lazy<T>(() => CreateSingletonInstance());

        public static T Instance
        {
            get
            {              
              //  throw new System.InvalidOperationException("out");
                return _instance.Value;
            }
        }

        private static T CreateSingletonInstance()
        {
            // Konstruktion des Singleton-Objekts
            return Activator.CreateInstance(typeof(T), true) as T;
        }
    }
}

and:

    class Account : AbstractAccount<Account>
    {
        // öffentliche Felder und Methoden
        public string Username { get; set; }
        public string Password { get; set; }
        public string Email { get; set; }

        public string Description { get; set; }
        public List<string>Friendlist { get; set; }
        public Bitmap ProfilePicutre { get; set; }
        public int Experience { get; set; }
        public int gender { get; set; }
        public DateTime lastLogin { get; set; }
        public DateTime dateCreated { get; set; }
        public string Locality { get; set; }
        public string Country { get; set; }
        public string CountryCode { get; set; }
        public int level { get; set; }


        public void SetCurrentAccount(tblUsers user, DateTime lastLogin)
        {
            this.Username = user.getUsername();
            this.Email = user.getEmail();
            this.Password = user.getPassword();
            this.Description = user.getdescription();
            this.Experience = user.getexperience();
            this.gender = user.getgender();
            this.lastLogin = lastLogin;
            this.dateCreated = user.getDateCreated();
            this.level = CheckLevel(Experience);                     
        }
}

Now here is the issue: When a user is login off and then creating a new account, he or she would still be set up with the properties of the user he just logged out off.

For instance: If he had 1000 xp points, then loggs off and creates a new account, that account would not start at 0 points but at 1000.

I know that his is pretty much (maybe even impossible) for you to handle from another computer but I really need help right here:

    private void logoutClick(object sender, EventArgs e)
    {
        Context mContext = Android.App.Application.Context;
        AppPreferences ap = new AppPreferences(mContext);
        ap.deletePreferences();
        this.FinishAffinity();

        //Remove static variables. Just to be sure!
        SaveAccountInfo.bpLandScapePicFull = null;
        SaveAccountInfo.bpLandScapePicThumb = null;
        SaveAccountInfo.bpProfilePicFull = null;
        SaveAccountInfo.bpProfilePicThumb = null;

        StartActivity(typeof(Activity_AcctCreationLogin));
        Finish();
    }

If the user was now to logout, the singleton needs to be completely destroyed and set up anew when a nother account is beeing created. I tried "Account.Instance.Dispose()" but unfortunately, there was no such method as "dispose" after instance.

Is there any chance you guys could help me out a little? That me tremendous! Thanks so much! :)

Upvotes: 0

Views: 1031

Answers (3)

casiosmu
casiosmu

Reputation: 827

You should youse the Singleton pattern with these 2 methods: 

public static T GetInstance
{
    get
    {   
       if (_instance == null)
         _instance = new Lazy<T>(() => CreateSingletonInstance());
       return _instance.Value;
    }
}
public static void ReleaseInstance   // called on logout
{
    _instance = null;
}

also, as DavidG pointed out you should add a protected constructor.

Upvotes: 1

jbuchan12
jbuchan12

Reputation: 36

Would it be possible for you to implement the IDisposable interface, then write your own dispose method. You could then use this method to clear the data you want cleared. Hope this helps.

Upvotes: 0

tompee
tompee

Reputation: 1408

You can set the value of your instance to a new one.

Create a method in your Account class that does this one upon logout.

 _instance = new Lazy<T>(() => CreateSingletonInstance());

Upvotes: 4

Related Questions