标题:求助一个问题?
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王杰
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注 册:2005-5-13
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求助一个问题?

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

namespace listbox
{
/// <summary>
/// Form1 的摘要说明。
/// </summary>
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.Label label1;
private System.Windows.Forms.Label label2;
private System.Windows.Forms.ListBox listBox1;
private System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.Button button1;
private System.Windows.Forms.Button button2;
/// <summary>
/// 必需的设计器变量。
/// </summary>
private System.ComponentModel.Container components = null;

public Form1()
{
//
// Windows 窗体设计器支持所必需的
//
InitializeComponent();

//
// TODO: 在 InitializeComponent 调用后添加任何构造函数代码
//
}

/// <summary>
/// 清理所有正在使用的资源。
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}

#region Windows 窗体设计器生成的代码
/// <summary>
/// 设计器支持所需的方法 - 不要使用代码编辑器修改
/// 此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.label1 = new System.Windows.Forms.Label();
this.label2 = new System.Windows.Forms.Label();
this.listBox1 = new System.Windows.Forms.ListBox();
this.textBox1 = new System.Windows.Forms.TextBox();
this.button1 = new System.Windows.Forms.Button();
this.button2 = new System.Windows.Forms.Button();
this.SuspendLayout();
//
// label1
//
this.label1.Location = new System.Drawing.Point(16, 40);
this.label1.Name = "label1";
this.label1.TabIndex = 0;
this.label1.Text = "同学录";
//
// label2
//
this.label2.Location = new System.Drawing.Point(160, 40);
this.label2.Name = "label2";
this.label2.TabIndex = 1;
this.label2.Text = "新同学";
//
// listBox1
//
this.listBox1.ItemHeight = 12;
this.listBox1.Items.AddRange(new object[] {
"张三",
"李四",
"王五"});
this.listBox1.Location = new System.Drawing.Point(16, 72);
this.listBox1.Name = "listBox1";
this.listBox1.Size = new System.Drawing.Size(120, 88);
this.listBox1.TabIndex = 2;
this.listBox1.SelectedIndexChanged += new System.EventHandler(this.listBox1_SelectedIndexChanged);
//
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(152, 72);
this.textBox1.Name = "textBox1";
this.textBox1.TabIndex = 3;
this.textBox1.Text = "";
//
// button1
//
this.button1.Location = new System.Drawing.Point(160, 104);
this.button1.Name = "button1";
this.button1.TabIndex = 4;
this.button1.Text = "添加";
this.button1.Click += new System.EventHandler(this.button1_Click);
//
// button2
//
this.button2.Location = new System.Drawing.Point(160, 136);
this.button2.Name = "button2";
this.button2.TabIndex = 5;
this.button2.Text = "删除";
this.button2.Click += new System.EventHandler(this.button2_Click);
//
// Form1
//
this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
this.ClientSize = new System.Drawing.Size(292, 266);
this.Controls.Add(this.button2);
this.Controls.Add(this.button1);
this.Controls.Add(this.textBox1);
this.Controls.Add(this.listBox1);
this.Controls.Add(this.label2);
this.Controls.Add(this.label1);
this.Name = "Form1";
this.Text = "Form1";
this.Load += new System.EventHandler(this.Form1_Load);
this.ResumeLayout(false);

}
#endregion

/// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
{
Application.Run(new Form1());
}


private void button1_Click(object sender, System.EventArgs e)
{
if (textBox1.Text!="")
listBox1.Items.Add(textBox1.Text);
}

private void button2_Click(object sender, System.EventArgs e)
{
listBox1.Items.Remove(listBox1.SelectedItem.ToString());
textBox1.Text="";
}
private void listBox1_SelectedIndexChanged(object sender, System.EventArgs e)
{
textBox1.Text=listBox1.SelectedItem.ToString(); //在删除的时候这里会出现异常
}

private void Form1_Load(object sender, System.EventArgs e)
{

}

}
}

搜索更多相关主题的帖子: System Forms using Windows private 
2005-11-10 16:44
sjcries
Rank: 1
等 级:新手上路
帖 子:35
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注 册:2005-10-30
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出错原因是当你删除了一项后该项就消失了 那么listbox的selecteditem是空的

if(listBox1.SelectedItem != null)
{

try
{
listBox1.Items.Remove(listBox1.SelectedItem.ToString());
}
catch(Exception ex)
{
string errormsg = ex.Message;
}
textBox1.Text="";
}

这段来替换//在删除的时候这里会出现异常 的代码就可以了

2005-11-10 16:56
sjcries
Rank: 1
等 级:新手上路
帖 子:35
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注 册:2005-10-30
得分:0 
还有 上面点删除的时候最好也加上保护 否则当当前没有选择的时候还是会出现问题的
2005-11-10 16:57
王杰
Rank: 2
等 级:新手上路
威 望:4
帖 子:307
专家分:0
注 册:2005-5-13
得分:0 

谢谢!


http://zdrjwlb.bulo. QQ群:1659819
2005-11-11 14:47
唐伯猫
Rank: 8Rank: 8
等 级:贵宾
威 望:45
帖 子:5323
专家分:58
注 册:2005-8-9
得分:0 
我想
if(listBox1.SelectedItem != null)
{

try
{
listBox1.Items.Remove(listBox1.SelectedItem.ToString());
}
catch(Exception ex)
{
string errormsg = ex.Message;
}
textBox1.Text="";
}
应该来替换
listBox1.Items.Remove(listBox1.SelectedItem.ToString());
textBox1.Text="";
如果再在
if (textBox1.Text!="")
listBox1.Items.Add(textBox1.Text);
后加上:this.textBox1.Clear();
就更完美一点了.


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2005-11-12 11:06



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