1. 靜態(tài)單例

using System;
using System.Collections.Generic;

namespace InstanceTest
{
    public class DogManager {
        public static readonly DogManager Instance = new DogManager();

        private DogManager() { }

        public void Eat() {
            Console.WriteLine("吃");
        }
    }
     
    class Program
    {
        static void Main(string[] args)
        {
            DogManager.Instance.Eat();
        }
    }
}

2.延時單例

using System;
using System.Collections.Generic;

namespace InstanceTest
{
    public class DogManager {
        private static DogManager _instance = null;

        private DogManager() { }

        public static DogManager Insance() {
            if (_instance == null) {
                _instance = new DogManager();
            }
            return _instance;
        }

        public void Eat() {
            Console.WriteLine("吃");
        }
    }
     
    class Program
    {
        static void Main(string[] args)
        {
            DogManager.Insance().Eat();
        }
    }
}

注意把構造函數(shù)寫成private，讓他不能通過new獲得。