Angular 2 Interview Questions and Answers

Best Use of C# Private Constructors [How To?]

What do we need of private constructor in C#?
1.A private constructor means that the class can't be instantiated from outside the class.
2.Private constructors can be useful when using a factory pattern.
3.You cannot add public constructor without parameters. i.e.



4.If the class ONLY has private constructors, it cannot be instantiated from outside.



5.When you want to prevent the users of your class from instantiating the class directly.
6.A static method can call the private constructor to create a new instance of that class.
7.In this case, you have a static method defined inside the class that internally calls the private constructor. i.e.
class A
{
private A() { }
private static A theA = new A();
public static A getAInstance() { return theA; }
}

8.If you want to create object of class(ClassA) even if we have private constructor(ClassA) then we need to add a public parameterise constructor along with private constructor. i.e.

             namespace ConsoleNamespace
             {
                class ClassA
                {
                    private ClassA()
                    {
                        Console.WriteLine("ClassA::Constructor()");
                    }

                    public ClassA(int a)
                    {
                        Console.WriteLine("ClassA with params::Constructor()");
                    }
                 }
                 class Test
                 {
                    static void Main(string[] args)
                    {
                        ClassA a = new ClassA(10);
                        Console.ReadLine();
                    }
                 }
              }

Constructor Interview Questions and Answers

ANIL SINGH

Hey! I'm Anil Singh. I author this blog. I'm Active Blogger, Programmer. I love learning new technologies, programming, blogging and participating the forum discussions more...
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