Instantiation With Private Constructor in C# - Singleton Pattern

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Instantiation With Private Constructor in C# - Singleton Pattern

Shervan360 1,681

Hello,

From what I understood, If we use a private constructor in our class, We cannot instantiate from the class. ( We cannot use a new keyword to instantiate)

In the below example, I use instance = new Language(); in the getter and I don't have any error.

 public class Language
    {
        private Language() { }
        private static Language instance;
        public static Language Instance
        {
            get
            {
                if (instance == null)
                    instance = new Language();
                return instance;
            }
        }
    }

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Answer 1

Karen Payne MVP 35,606 Volunteer Moderator

Here is how to use a private constructor.

public sealed class Singleton
{
    private static readonly Lazy<Singleton> Lazy = new(() => new Singleton());
    public static Singleton Instance => Lazy.Value;
    public DateTime DateTime { get; set; }

    private Singleton()
    {
        DateTime = DateTime.Now;
    }
}

Then to call Singleton.Instance.DateTime the constructor is only called the first time.

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Answer 2

P a u l 10,766

private means it's only accessible from the current class and your Instance getter is within the Language class. If you tried to instantiate Language from outside of the class you'd get an error.

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Instantiation With Private Constructor in C# - Singleton Pattern

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