有关SelectedValue,SelectedItem,Text

 public partial class Form1 : Form
    {
        DataTable dtblTemp;
        public Form1()
        {
            InitializeComponent();
            InitialTable();
            FillComboBox();
        }
        void InitialTable()
        {
            dtblTemp = new DataTable();
            DataColumn dcolId = new DataColumn("Id", System.Type.GetType("System.String"));
            dtblTemp.Columns.Add(dcolId);
            DataColumn dcolName = new DataColumn("Name", System.Type.GetType("System.String"));
            dtblTemp.Columns.Add(dcolName);
        }
        void FillComboBox()
        {
            for (int j = 0; j < 10; j++)
            {
                comboBox1.Items.Add(j.ToString());
            }

        }
        private void Form1_Load(object sender, EventArgs e)
        {
            for (int i = 0; i < 100; i++)
            {
                DataRow drowNew = dtblTemp.NewRow();
                drowNew["Id"] ="iD"+ i.ToString();
                drowNew["Name"] = "Name" + i.ToString();
                dtblTemp.Rows.Add(drowNew);
            }
            //绑定到listBox1
            listBox1.DisplayMember = "Name";
            listBox1.ValueMember = "Id";
            listBox1.DataSource = dtblTemp;
            //绑定到comboBox2
            comboBox2.DisplayMember = "Name";
            comboBox2.ValueMember = "Id";
            comboBox2.DataSource = dtblTemp;
        }

        private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (listBox1.SelectedIndex != -1)
            {
                //textBox1.Text = listBox1.SelectedItem.ToString();//System.Data.DataRowView 错误写法
                //textBox1.Text = listBox1.SelectedValue.ToString();//求到的是Id的值ValueMember的值
                textBox1.Text = listBox1.Text;//DisplayMember值
                DataRowView drv = (DataRowView)listBox1.SelectedItem;
                textBox1.Text = drv["Id"].ToString();//求得Id值(ValueMember)值
                textBox1.Text = drv["Name"].ToString();//DisplayMember值

            }
        }
        //直接填充数据
        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            //this.textBox2.Text = this.comboBox1.SelectedText.ToString();//为""
            //this.textBox2.Text = this.comboBox1.SelectedValue.ToString();//null异常
            //this.textBox2.Text = this.comboBox1.SelectedItem.ToString();//为comboBox中显示的内容
            this.textBox2.Text = this.comboBox1.Text;//为comboBox中显示的内容,
        }
        //绑定到表与直接填充数据值有差别this.comboBox2.SelectedItem.ToString()
        private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (comboBox2.SelectedIndex!= -1)
            {
                //this.textBox3.Text = this.comboBox2.SelectedItem.ToString();////System.Data.DataRowView 错误写法

                //this.textBox3.Text = this.comboBox2.Text;//与直接填充时一样
                this.textBox3.Text = this.comboBox2.SelectedValue.ToString();//得到ValueMember的值
                DataRowView drv = (DataRowView)comboBox2.SelectedItem;//此时SelectedItem属性是DataRowView对象
                //this.textBox3.Text = drv["Id"].ToString();
                this.textBox3.Text = drv["Name"].ToString();

            }
        }
    }

//当listBox与comboBox都绑定到表时,用法一样,当comboBox绑定到表与直接数据填充时,有区别.