Winform Combox DataSource 之不显示 displayemember 内容

刚开始学习数据绑定的东西，

private void Form1_Load(object sender, EventArgs e)
        {
            IList<TLayer> tt = new List<TLayer>();
            tt.Add(new TLayer("Layer1", "1"));
            tt.Add(new TLayer("Layer2", "2"));
            tt.Add(new TLayer("Layer3", "3"));
            tt.Add(new TLayer("Layer4", "4"));
            tt.Add(new TLayer("Layer5", "5"));
            comboBox1.DataSource = tt;
            comboBox1.DisplayMember = "NameN";
            comboBox1.ValueMember = "FL";
        }

        public class TLayer
        {
            public string NameN;public string FL;public TLayer(string NameN, string FL)
            {
                this.NameN = NameN;
                this.FL = FL;
            }
        }

代码如上，显示是这个样子的

网上的示例   http://www.cnblogs.com/shuang121/archive/2012/11/21/2780819.html

仔细对比发现，唯一的区别是示例中是对公有字段进行了属性封装。而这就是问题关键，修改后如下，即可正常显示

public class TLayer
        {
            public string NameN { get; set; }
            public string FL { get; set; }

            public TLayer(string NameN, string FL)
            {
                this.NameN = NameN;
                this.FL = FL;
            }
        }