C# 单例模式

using System.Windows.Forms;

namespace jjjjjj
{
    public partial class Form2 : Form
    {
        private static Form2 _ins;
        private Form2()
        {
            InitializeComponent();
        }

        public static Form2 GetSingle()
        {
            if (_ins==null)
            {
                _ins=new Form2();
            }
            return _ins;
        }

        private void Form2_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (_ins != null)
            {
                _ins = null;
            }
        }
    }
}