How do I pass element of static array to non static method?

Question

I have a static array and I need to pass an arbitrary element of it to a non-static method.

How do I do that?

public class MyClass
{
    public static int[] staticArray = { 3, 11, 43, 683, 2731 };

    public void SomeMethod(int value)
    {
        //...stuff...
    }

    public static void staticMethod()
    {
         SomeMethod(staticArray[2]);    //error here
    }
}

When I try something like that I get the error An object reference is required for the non-static field, method, or property.

The above code compile (if you replace ...stuff... with // ...stuff.... — Albin Sunnanbo
– Albin Sunnanbo, Commented Mar 2, 2013 at 14:51
Your code works fine for me in LinqPad. You must have simplified your test too much. — Kirk Woll
– Kirk Woll, Commented Mar 2, 2013 at 14:51
That code compiled perfectly fine.. paste the rest of it.. the error must be somewhere else in ...stuff.... or somewhere... — Matt
– Matt, Commented Mar 2, 2013 at 14:51
Runs fine for me used a breakpoint and 43 was in value as expected. — Daniel Imms
– Daniel Imms, Commented Mar 2, 2013 at 14:53

Bort · Accepted Answer · 2013-03-02 15:15:29Z

6

Your code as it is is fine, however 'An object reference is required for the non-static field, method, or property' occurs when you try to call instance method, or access a non-static field/property on something other than an instance of a class, say from a static method. For example:

class MyClass
{
    private int imNotStatic;

    public static void Bar()
    {
        // This will give you your 'An object reference is required` compile 
        // error, since you are trying to call the instance method SomeMethod
        // from a static method, as there is no 'this' to call SomeMethod on.
        SomeMethod(5);

        // This will also give you that error, as you are calling SomeMethod as
        // if it were a static method.
        MyClass.SomeMethod(42);

        // Again, same error, there is no 'this' to read imNotStatic from.
        imNotStatic = -1;
    }

    public void SomeMethod(int x)
    {
        // Stuff
    }
}

Ensure that you are not doing one of the above. Are you sure you are calling SomeMethod from a constructor?

edited Mar 2, 2013 at 15:15

answered Mar 2, 2013 at 15:01

Bort

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6 Comments

davecove Over a year ago

I appear to be doing exactly that... plz see my edited original post. So, how can I do what I need without the error? Dave

Bort Over a year ago

You can't, SomeMethod would need to be static for you to call it from a static method. Please refresh on the difference between static and instance methods, and hopefully that should give you insight into the correct way to solve your actual problem.

Bort Over a year ago

However, note that from within SomeMethod, you would have access to staticArray, which means instead of // stuff you could write int value = staticArray[2];

davecove Over a year ago

but if I can't call SomeMethod from staticMethod I can't get to int value = staticArray[2]; when another form calls staticMethod. The aim here is to allow other forms in the app to use MyClass.staticMethod(); to run SomeMethod which does stuff to MyClass via non-static props/methods.

Bort Over a year ago

That aim implies a misunderstanding of how static and instances differ. Say in your program you had MyClass a; MyClass b; When you call MyClass.staticMethod(); what instance would it call SomeMethod on? a, b? From within a static method there is no instance of MyClass to call non-static props/methods on

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