Using a list from another method in a static class

Question

So I have a static class with a list declared as one of it's members, and I populate the list in a function lets say it's called PopulateList(). Is it possible to modify the list in another function without:

1) Calling it as a parameter 2) Instantiating it in a constructer (Trying to keep the class static. I'm working off of a template so I can't really change the structure of the classes)

Without somehow instantiating though, I will obviously receive null exceptions, so I was wondering if there is a 3rd way to do this.

       public Static class MyClass{

             static public List<String> m_SuiteFileNameList2=null;


        public static bool Function1(inp){
              //m_SuiteFileNameList2 stuff
         }

        public static void Function2(){
             //m_SuiteFileNameList2 other stuff
          }
       }

Code would be a little better than only words, please could you add a bit code? — cuongle, Jul 16 '13 at 15:53
Please show some code. It's unclear why you can't initialize the member directly. — Daniel Hilgarth, Jul 16 '13 at 15:54
why not just check if the list is instantiated when running your function, then instantiate it if it isn't already? — James, Jul 16 '13 at 15:57

RoadieRich · Answer 1 · 2013-07-16T16:09:58.587

2

You can either use a static constructor, or static initialization. It will allow you to keep your class static, but will ensure that the list is always defined:

static class MyClass
{
    static MyClass()
    {
        MyList = new List<Whatever>();
    }

    // etc
}

or

static class MyClass
{
    public static List<Whatever> MyList = new List<Whatever>();
}

Another option is to add a null check to every usage of the list:

public static void MyMethod()
{
    if (MyList == null)
    {
        MyList = new List<Whatever>();
    }
    //etc
}

edited Jul 16 '13 at 16:09

answered Jul 16 '13 at 15:55

RoadieRich

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I'm still having some trouble with the Static Constructor. It says the list is a field but is used like a type. Also I get an invalid '{' in class struct or interface – user1819301 Jul 16 '13 at 16:09
@user1819301 I missed some parentheses from the first example. – RoadieRich Jul 16 '13 at 16:10
Thanks RoadieRich. That's the answer I was looking for. – user1819301 Jul 16 '13 at 16:15

score 1 · Answer 2 · edited May 23 '17 at 12:23

I would call a function called 'Initialize' which is static and takes care of your static members.

Though I would recommend against static members if possible.

Why?

They can lead to head aches (yes, that hurts)
Their behaviour in memory allocation is different (How is memory allocated for a static variable?)

code snippet

public static class YourClass
{
    public static List<string> YourList;

    public static void InitializeList()
    {
        YourList = new List<string>();
        YourList.Add("hello");
        YourList.Add("how");
        YourList.Add("are");
        YourList.Add("you?");
    }
}

Call your Initialize-Function from outside:

 YourClass.InitializeList();

EDIT: Given your code , you can also do it this way:

  public Static class MyClass{

             static public List<String> m_SuiteFileNameList2=null;


        public static bool Function1(inp){
             if(m_SuiteFileNameList2 == null)
             { m_SuiteFileNameList2 = new List<String>();}
              //m_SuiteFileNameList2 stuff
         }

        public static void Function2(){
             if(m_SuiteFileNameList2 == null)
             { m_SuiteFileNameList2 = new List<String>();}
             //m_SuiteFileNameList2 other stuff
          }
       }

I disagree with point 2 `They use memory even though you don't use the class (they live as long the project lives)` This is false unless you Use it atleast `Once` — Sriram Sakthivel, Jul 16 '13 at 16:04

Using a list from another method in a static class

2 Answers2