C# how can I preserve data between class instances?

Question

Apologies for the vague title, but I am not really sure how else to explain it.

Given Class A, B and C.

If Class A contains a List, how can I preserve the da

Answer 1

Use static as defined here: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/static

Then you will be able to access the class properties instead of instance properties.

Answer 2

You have multiple options to implement this. As said in other answer you can use Static property/field in Class A for accessing list.

Second option is to use Dependency injection. Create constructors of class B and class C so that they must be initialized by passing in instance of A. e.g.

class A
{
  public List<object> AList {get;set;}
}

class B
{
  private A localInstance;
  public B(A instance)
  {
    localInstance = instance;
  }

  public void SomeMethod()
  {
     // access to list from instance of A
     var a = localInstance.AList
  }
}

// Similar implementation for class c