//定义一个需要string类型参数的委托         publicdelegate void MyDelegate(string text);         public partial class Form2 :Form1         {                //定义该委托的事件             public event MyDelegate MyEvent;             public Form2(string text)             {                  InitializeComponent();                 this.textBox1.Text = text;            }            private void btnChange_Click(object sender, EventArgs e)                          {                //触发事件，并将修改后的文本回传                MyEvent(this.textBox1.Text);                this.Close();             }        }

public partial class Form1 :Form         {             public int index = 0;             public string text = null;             public Form1()             {                 InitializeComponent();             }             private void listBox1_SelectedIndexChanged(object sender, EventArgse)             {                 if (this.listBox1.SelectedItem != null)                 {                     text = this.listBox1.SelectedItem.ToString();                     index = this.listBox1.SelectedIndex;                     Form2 form2 = new Form2(text);                    //注册form2_MyEvent方法的MyEvent事件                     form2.MyEvent += new MyDelegate(form2_MyEvent);                     form2.Show();                 }             }            //处理             void form2_MyEvent(string text)             {                 this.listBox1.Items.RemoveAt(index);                 this.listBox1.Items.Insert(index, text);            }        }