Question

我有一个listView，当我从listview中选择其他值时，它会给出错误

invalid argument value of 0 is not valid for index

代码是这样的：

UserList = getUsers();            
for (int i = 0; i < UserList.Count; i++)
        {
            User user = UserList.ElementAt(i);

            ListViewItem row = new ListViewItem();
            row.Text = user.name.ToString();
            row.SubItems.Add(user.surname);
            row.Tag = user.weight.ToString();
            row.Tag = user.height.ToString();
            row.Tag = user.id;

            listView1.Items.Add(row);
        }

userList是来自xml文件的列表：

    public List<User> getUsers()
    {
        XmlNodeList nodes = xmlDoc.DocumentElement.SelectNodes("/users/user");

        foreach (XmlNode node in nodes)
        {
            User user = new User();
            user.id = Convert.ToInt32(node.SelectSingleNode("id").InnerText);
            user.name = node.SelectSingleNode("name").InnerText;
            user.surname = node.SelectSingleNode("surname").InnerText;
            user.weight = Convert.ToInt32(node.SelectSingleNode("weight").InnerText);
            user.height = Convert.ToInt32(node.SelectSingleNode("height").InnerText);

            UserList.Add(user);
        }

        return UserList;
    }

如何摆脱错误？

- 编辑：

它在这里出错：

public List<UserData> getAllUsers()
{
    var id = (int)listView1.SelectedItems[0].Tag; // ERROR in this line
    var currenTask = UserList.Where(t => t.id == id).First();
    SqlConnection conn = Program.getConnection;
    SqlDataReader rdr = null;
    try
    {
        string query = "SELECT * FROM personalData where user_id = @user_id";
        SqlCommand cmd = new SqlCommand(query, conn);
        SqlParameter user_id = cmd.Parameters.Add("@user_id", SqlDbType.Int);
        user_id.Value = currenTask.id;
        rdr = cmd.ExecuteReader();
        while (rdr.Read())
        {
            UserData userData = new UserData();

            userData.id = rdr.GetInt32(0);
            userData.mode = rdr.GetString(1);
            userData.time_preview = rdr.GetString(2);
            userData.time = rdr.GetInt32(3);
            userData.callories_lost = rdr.GetDouble(4);
            userData.date = rdr.GetDateTime(5);
            userData.user_id = rdr.GetInt32(6);

            userData = userData.createUser(userData.id, userData.mode, userData.time_preview, userData.time, userData.callories_lost, userData.date, userData.user_id);
            UserDataList.Add(userData);

        }
        rdr.Close();
    }
    finally
    {
        if (rdr != null) { rdr.Close(); }
        if (conn != null) { conn.Close(); }
    }
    return UserDataList;
}

错误在评论中

Answer 1

如果没有用户怎么办？您的循环仍将运行，因为0不小于0.

使用<=代替<。

for (int i = 0; i <= UserList.Count; i++)

无效的参数值0对索引无效

1 个答案: