#294 – Make All Constructors Private to Prevent Object Creation

If you want to prevent code external to a class from creating instances of that class, you can make all of the constructors of the class private.

In the following example, we have a single Dog constructor, which is private.

        private Dog(string name, int age)
        {
            Name = name;
            Age = age;
        }

Because the constructor is private, code outside the Dog class cannot create a new instance of a Dog.

But we can have a static method in the Dog class that can create instances.  Because the code is defined inside the Dog class, it has access to the private constructor.

public class Dog
{
        // code omitted

        public static Dog MakeADog()
        {
            // Use private constructor
            Dog nextDog = new Dog(nameList[nextDogIndex], ageList[nextDogIndex]);

            nextDogIndex = (nextDogIndex == (nameList.Length - 1)) ? 0 : nextDogIndex++;

            return nextDog;
        }

Now if we want a new Dog instance, we can call the MakeADog method.

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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

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