在助手类中使用静态方法与非静态方法

Question

I have a helper class that takes some object, processes it and returns back some instance of the other class or even the List of the objects. What would be the best way: to make this helper method static or non-static? The thing is that my app can create lots of the Car objects and I was thinking whether it could have a negative effect when each of them use the static helper?

Answer 1

Most helper or utility classes use static methods. You should only use non-static methods if you want to create multiple instances of your helper class, but since you just need a simple input -> function -> output, I would make the methods static.

Answer 2

Probably this is something that can be solved without deciding the helper object's life-cycle where you require it.

You should try to leverage dependency injection approach:

public class X
{
   public X(IHelper helper)
   {
        Helper = helper;
   }

   private IHelper Helper { get; }

   public void DoStuff() 
   {
        var result = Helper.DoOtherStuff(input);
   }
}

That is, X don't know whether Helper is always the same instance or if it's a transient object. This makes the code cleaner and more test-friendly, because you can mock the helper with a fake IHelper implementation to be sure that you're just testing X .

Answer 3

Use static class with static methods, No instance, no derivation and only static methods in the class.

public static class HelperClass
{
   public static void HelperMethod()
   {
       // do something
   } 
}