public class SingleTon

{

    private static SingleTon singleTon = null;//声明并初始化为null

    public SingleTon()

    {  

    }  

    /// <summary>

    /// 创建SingleTon对象

    /// </summary>

    /// <returns></returns>

    public static SingleTon GetInstance()

    {

        if (singleTon == null)

        {

            singleTon = new SingleTon();

        }

        return singleTon;

    }  

    /// <summary>

    /// 调用测试方法

    /// </summary>

    public void Print()

    {

        Console.WriteLine("打印吧");

    }

}  

class Program

{

    static void Main(string[] args)

    {

        //单例模式

        SingleTon singleTon1 = SingleTon.GetInstance();

        SingleTon singleTon2 = SingleTon.GetInstance();

        SingleTon singleTon3 = SingleTon.GetInstance();

        SingleTon singleTon4 = SingleTon.GetInstance();

        SingleTon singleTon5 = SingleTon.GetInstance();  

        if (singleTon1 == singleTon2 && singleTon2 == singleTon3 && singleTon3 == singleTon4 && singleTon4 == singleTon5)

        {

            Console.WriteLine("相等");

            singleTon1.Print();

        }

    }

}