如何使ListBox刷新其项目文本？

Question

我正在为一个尚未意识到控件的人做一个例子,ListBox不需要包含字符串; 他一直在存储格式化的字符串并跳过复杂的解析箍,以便将数据从中恢复出来,ListBox我想告诉他有更好的方法.

我注意到如果我有一个对象存储在ListBox然后更新一个影响的值ToString,则ListBox不会自行更新.我试过打电话Refresh和Update控制,但都不起作用.这是我正在使用的示例的代码,它要求您将列表框和按钮拖到窗体上:

Public Class Form1

    Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)
        MyBase.OnLoad(e)

        For i As Integer = 1 To 3
            Dim tempInfo As New NumberInfo()
            tempInfo.Count = i
            tempInfo.Number = i * 100
            ListBox1.Items.Add(tempInfo)
        Next
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        For Each objItem As Object In ListBox1.Items
            Dim info As NumberInfo = DirectCast(objItem, NumberInfo)
            info.Count += 1
        Next
    End Sub
End Class

Public Class NumberInfo

    Public Count As Integer
    Public Number As Integer

    Public Overrides Function ToString() As String
        Return String.Format("{0}, {1}", Count, Number)
    End Function
End Class

我想也许问题是使用字段并尝试实现INotifyPropertyChanged,但这没有任何效果.(我使用字段的原因是因为它是一个例子,我不想添加几十行与我正在演示的主题无关.)

老实说,我以前从未尝试过更新这样的物品; 在过去,我一直在添加/删除项目,而不是编辑它们.所以我从来没有注意到我不知道如何使这项工作.

那我错过了什么？

Answer 1

当我需要一个更新的列表框时,我使用这个类.

更新列表中的对象,然后调用其中一个包含的方法,具体取决于您是否有可用的索引.如果要更新列表中包含的对象,但没有索引,则必须调用RefreshItems并更新所有项目.

public class RefreshingListBox : ListBox
{
    public new void RefreshItem(int index)
    {
        base.RefreshItem(index);
    }

    public new void RefreshItems()
    {
        base.RefreshItems();
    }
}

Answer 2

lstBox.Items[lstBox.SelectedIndex] = lstBox.SelectedItem;

Answer 3

BindingList处理自己更新绑定.

using System;
using System.ComponentModel;
using System.Windows.Forms;

namespace TestBindingList
{
    public class Employee
    {
        public string Name { get; set; }
        public int Id { get; set; }
    }

    public partial class Form1 : Form
    {
        private BindingList<Employee> _employees;

        private ListBox lstEmployees;
        private TextBox txtId;
        private TextBox txtName;
        private Button btnRemove;

        public Form1()
        {
            InitializeComponent();

            FlowLayoutPanel layout = new FlowLayoutPanel();
            layout.Dock = DockStyle.Fill;
            Controls.Add(layout);

            lstEmployees = new ListBox();
            layout.Controls.Add(lstEmployees);

            txtId = new TextBox();
            layout.Controls.Add(txtId);

            txtName = new TextBox();
            layout.Controls.Add(txtName);

            btnRemove = new Button();
            btnRemove.Click += btnRemove_Click;
            btnRemove.Text = "Remove";
            layout.Controls.Add(btnRemove);

            Load+=new EventHandler(Form1_Load);
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            _employees = new BindingList<Employee>();
            for (int i = 0; i < 10; i++)
            {
                _employees.Add(new Employee() { Id = i, Name = "Employee " + i.ToString() }); 
            }

            lstEmployees.DisplayMember = "Name";
            lstEmployees.DataSource = _employees;

            txtId.DataBindings.Add("Text", _employees, "Id");
            txtName.DataBindings.Add("Text", _employees, "Name");
        }

        private void btnRemove_Click(object sender, EventArgs e)
        {
            Employee selectedEmployee = (Employee)lstEmployees.SelectedItem;
            if (selectedEmployee != null)
            {
                _employees.Remove(selectedEmployee);
            }
        }
    }
}

Answer 4

typeof(ListBox).InvokeMember("RefreshItems", 
  BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.InvokeMethod,
  null, myListBox, new object[] { });

Answer 5

在数据源和列表框的datasource属性之间使用datasource属性和BindingSource对象.然后刷新.

更新添加的示例.

像这样:

Public Class Form1

    Private datasource As New List(Of NumberInfo)
    Private bindingSource As New BindingSource

    Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)
        MyBase.OnLoad(e)

        For i As Integer = 1 To 3
            Dim tempInfo As New NumberInfo()
            tempInfo.Count = i
            tempInfo.Number = i * 100
            datasource.Add(tempInfo)
        Next
        bindingSource.DataSource = datasource
        ListBox1.DataSource = bindingSource
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        For Each objItem As Object In datasource
            Dim info As NumberInfo = DirectCast(objItem, NumberInfo)
            info.Count += 1
        Next
        bindingSource.ResetBindings(False)
    End Sub
End Class

Public Class NumberInfo

    Public Count As Integer
    Public Number As Integer

    Public Overrides Function ToString() As String
        Return String.Format("{0}, {1}", Count, Number)
    End Function
End Class