Creating An Utilities Class?

Question

Hello SO,

I'm very new to OOP and am trying my hardest to keep things strictly class based, while using good coding priciples.

I'm a fair ways into my project now and I have a lot of general use methods I want to put into an utilities class. Is there a best way to create an utilities class?

public class Utilities
{
    int test;

    public Utilites()
    {
    }

    public int sum(int number1, int number2)
    {
        test = number1+number2;
    }
    return test;
}

After creating this Utilities class, do I just create an Utilities object, and run the methods of my choosing? Do I have this Utilities class idea correct?

Answer 1

You should make it a static class, like this:

public static class Utilities {
    public static int Sum(int number1, int number2) {
        return number1 + number2;
    }
}

int three = Utilities.Sum(1, 2);

The class should (usually) not have any fields or properties. (Unless you want to share a single instance of some object across your code, in which case you can make a static read-only property.

Answer 2

Best is to make the functions not reliable to members of a class. Therefore you can make the functions static.

Better is to make the functions an extension method of a type. see here for example

Answer 3

You will be better off using a static class with static methods. Then you won't need to instantiate your utilities class to use it. It will look something like this:

public static Utilites
{
  public static int sum(int number1, int number2)
  {
     test = number1+number2;
     return test;
  }
}

Then you can use it like this:

int result = Utilites.sum(1, 3);

Answer 4

do this.

public static class Utilities
{
    int test;

    public static int sum(int number1, int number2)
    {
        test = number1+number2;
        return test;
    }
}

That way you use it like

int result = Utilities.sum(1, 2);

Answer 5

If you are working with .NET 3.0 or above, you should look into extension methods. They allow you to write a static function that will act against a particular type, like Int32, while seeming to be a menthod on that object. So then you could have: int result = 1.Add(2);.

Try this tutorial out. It might just show you another way. ;)

http://www.switchonthecode.com/tutorials/csharp-tutorial-extension-methods

Answer 6

While new to OOP and trying to get a handle on best practices, it may be a good idea to try to avoid utility classes. You could redesign your class like

public class Sum
{
    private int _result;

    public int Result {
       get {
           return _result;
       }
    }

    public Sum(int startNum) {
        _results = startNum;
    }

    public void Add(int num) {
        _result += num;
    }
}

And is called like:

Sum sum = new Sum(1);
sum.add(2);
int result = sum.Result;

It'll be good practice until further experience with OOP can help you examine the trade-offs of using an utility class vs pure OOP principles.