Question

大家好，我正在开展一个小项目，我正在添加，删除和更新文件而不是数据库中的项目。我有一个列表视图和列表，我在列表视图中添加项目在UI和列表中的对象。但是当我删除项目从列表视图中删除但不是列表中的对象并抛出异常。代码是以下和行问题和问题表明。

    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;
    using System.IO;


   namespace Address_Book_students
  {
    public partial class Form1 : Form
  {
    public Form1()
    {
        InitializeComponent();
    }
    List<student> boy = new List<student>();

    private void Form1_Load(object sender, EventArgs e)
    {
        String path = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
        if (!Directory.Exists(path + "\\Address_project_irfan"))
            Directory.CreateDirectory((path + "\\Address_project_irfan"));
        if (!File.Exists(path + "\\Address_project_irfan\\setting.xml"))
            File.Create((path + "\\Address_project_irfan\\setting.xml"));

    }

    private void button2_Click(object sender, EventArgs e)
    {
        student b = new student();
        b.Name = textBox1.Text;
        b.Address = textBox2.Text;
        b.Email = textBox3.Text;
        b.Birthday = dateTimePicker1.Value;
        b.Additional_info = textBox4.Text;
        listView1.Items.Add(textBox1.Text);
        boy.Add(b); // when i add the items in the listview1 at same time object is 
                    // object is b is added to the lis boy
        textBox1.Text = "";
        textBox2.Text = "";
        textBox3.Text = "";
        dateTimePicker1.Value = DateTime.Now;
        textBox4.Text = "";


    }
    public void Remove()
    {
       listView1.Items.Remove(listView1.SelectedItems[0]);
        boy.RemoveAt(listView1.SelectedItems[0].Index);//But when i remove items from
                                                       //the listview1 the items deleted
                                                       //from the listview but the object
                                                       // is not deleting from the list 
                                                       //boy throwing the exception(Value of 0 is not
                                                       //a valid arguement) what the problems here with list?


    }

    private void button3_Click(object sender, EventArgs e)
    {
        Remove();
    }



}
public class student
{
    public string Name
    {
        get;
        set;

    }
    public string Address
    {
        get;
        set;

    }
    public string Email
    {
        get;
        set;

    }
    public DateTime Birthday
    {
        get;
        set;

    }
    public string Additional_info
    {
        get;
        set;

    }

}
 }

Answer 1

您正在使用listView1.SelectedItems[0]查看选择了哪个项目 - 两次，一次用于从ListView中删除它，另一次用于从列表中删除它。

不幸的是，在您从ListView中删除它后，listView1.SelectedItems[0]不再存在，因此您将获得例外。

最简单的解决方法 - 首先从列表中删除项目，然后从ListView中删除。

Answer 2

我认为你最好得到这个对象，然后从列表中删除它然后重新绑定listview。

student stu = (student)boy.Where(s => s.Id == (int)listView1.SelectedValue)).Single();
boy.Remove(stu);

然后重新绑定您的列表视图。这确实表明你有一个男孩的Id，所以它的独特之处。但您可以使用其他字段之一，但您希望它是唯一的。

如何从C＃中的列表中删除对象

2 个答案: