Form2：

复制代码 代码如下:
//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();
}
}

Form1:

复制代码 代码如下:
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);
}
}