如何从另一个类实例调用一个类方法

Question

I'm new to C# , I'm in doubt about how to make this work:

namespace Core {
    public class A{
        private reandonly string _var;
        public A(string var){
            _var=var
        }
        public GetValue() => return _var;
    }
}

using System;
namespace Core.Resources {
    public static class B{
        public static void DoSomething(){
            Console.Writeline($"{A.GetValue()}");
        }
    }
}

public class C{
    static void Main(string args[]){
        A a = new A("name");
        a.Resources.B.DoSomething();
    }
}

A is in main folder, B is in Main/Resources folder, together they make a classlib, Program.cs is using this lib. Is there a way to make this work?

Answer 1

If you write a.Resources you are basically trying to retrieve the member Resources of the class A , which is obviously not defined. Since B is a static class defined in the Core.Resources namespace, all you have to do is to change your code as follows:

public class C
{
    public static void Main(string args[])
    {
        A a = new A("A");
        Core.Resources.B.DoSomething();
    }
}

or, alternatively, if you don't want to reference the namespace every time:

using Core.Resources;

public class C
{
    public static void Main(string args[])
    {
        A a = new A("A");
        B.DoSomething();
    }
}

Note that if yuu explicitly define a public constructor for A that accepts one or more arguments, the default parameterless constructor is no more available... hence you have to pass a string to the A constructor if you don't want to see an error in your console. Alternatively, you have to rewrite your A class so that it implements a default parameterless compiler, for example:

public class A
{
    private reandonly String _var;

    public A() : this(String.Empty) { }

    public A(String var)
    {
        _var = var;
    }
}

EDIT AS PER OP COMMENTS AND QUESTION CHANGES

public class A
{
    private reandonly String _var;

    public String Var
    {
        get { return _var; }
    }

    public A(String var)
    {
        _var = var;
    }
}

public static class B
{
    public static void DoSomething(String text)
    {
        Console.Writeline(text);
    }
}

public class C
{
    public static void Main(string args[])
    {
        A a = new A("name");
        B.DoSomething(a.Var);
    }
}