Object reference not set to an instance of an object [duplicate]

This question already has answers here: What is a NullReferenceException, and how do I fix it? (27 answers) Closed 8 years ago.

I had this working yesterday but I must of changed something now ListActiveLogins.ActiveLogins is null, what did i do?

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        new ListLogin(2);
        Console.WriteLine(ListLogin.LoginList.Length);
        Console.WriteLine(ListLogin.loginC);
        new ListActiveLogins(2);
        Console.WriteLine(ListActiveLogins.ActiveLogins.Length);
    }
}

public class ListLogin
{
    public static int loginC;
    public static 开发者_JAVA百科string[,] LoginList;
    public ListLogin(int loginCount)
    {
        LoginList = new string[loginCount, 3];
        loginC = loginCount;
    }
    public int LoginCount
    {
        get { return loginC; }
    }
    public string this[int row, int col]
    {
        get
        {
            return LoginList[row, col];
        }
        set
        {
            LoginList[row, col] = value;
        }
    }
}

public class ListActiveLogins
{
    public static Process[] ActiveLogins;
    public ListActiveLogins(int loginCount)
    {
        Process[] ActiveLogins = new Process[loginCount];
    }
    public Process this[int i]
    {
        get
        {
            return ActiveLogins[i];
        }
        set
        {
            ActiveLogins[i] = value;
        }
    }
}

---

You're making a separate local variable in the constructor.

---

The problem is that you declared a local variable in your ListActiveLogins constructor.

This should fix it.

public class ListActiveLogins
{
    public static Process[] ActiveLogins;
    public ListActiveLogins(int loginCount)
    {
        ActiveLogins = new Process[loginCount];
    }

---

Process[] ActiveLogins = new Process[loginCount];

is being re-declared as a local variable. Change it to:

ActiveLogins = new Process[loginCount];