listbox demo

功能

添加、删除、修改选中的项、上移、下移、清空、保存列表、加载列表、判断内容是否重复、查找、模糊查找、取消选择、上一条、下一条、第一条、最后一条

下载地址：https://download.csdn.net/download/u012663700/11994849

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;

namespace ListBoxDemo
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            SetupButtonEnabled();
        }

        //设置按钮的可用和不可用
        private void SetupButtonEnabled()
        {
            string s = textBox1.Text.Trim();
            int i = listBox1.SelectedIndex;
            int count = listBox1.Items.Count;

            //添加
            btnAdd.Enabled = !listBox1.Items.Contains(s) && s.Length > 0 && !s.Contains(",");

            //删除
            btnDel.Enabled = i != -1;

            //重命名
            btnRename.Enabled = i != -1 && listBox1.Items[i].ToString() != s;

            //上移
            btnMoveUp.Enabled = i - 1 >= 0;

            //下移
            btnMoveDown.Enabled = i + 1 < listBox1.Items.Count && i != -1; 

            //第一条
            btnFirst.Enabled = count > 0 && i != 0;

            //最后一条
            btnLast.Enabled = i != count - 1; 

            //上一条
            btnPre.Enabled = count > 0 && i != 0 && i != -1;

            //下一条
            btnNext.Enabled = i != count - 1 && i != -1;

            //搜索
            btnFind.Enabled = textBox1.Text.Trim().Length > 0;

            //模糊搜索
            btnFind1.Enabled = btnFind.Enabled;

            //取消选择
            btn取消选择.Enabled = i != -1;
        }

        private void 添加文本_Click(object sender, EventArgs e)
        {
            string s = textBox1.Text.Trim();
            if (s == "")
            {
                MessageBox.Show("内容不能为空或空格", "操作取消", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
            }
            else
            {      
                    /*
                     * 不添加列表中已经存在的内容， 
                     */
                listBox1.Items.Add(s);
            }
            textBox1.Text = "";
            textBox1.Focus();
        }

        private void 修改选中的项_Click(object sender, EventArgs e)
        {
            /*
             * 可以通过这样直接修改指定的项的值   listBox1.Items[i] = "指定值";
             *   
             */
            string s = textBox1.Text;
            int i = listBox1.SelectedIndex;
            if (i != -1)
            {
                if (listBox1.Items[i].ToString() != s)
                {
                    listBox1.Items[i] = s;
                       
                    s = listBox1.Items[i].ToString();
                }
                else
                {
                    MessageBox.Show("名字相同", "不用重新命名", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                }
            }
        }

        private void 删除选中的项_Click(object sender, EventArgs e)
        {
            /*
             * 这里的操作是 一次只删除一项
             */
            int i = listBox1.SelectedIndex;
            if (i != -1)
            {
                DialogResult d = MessageBox.Show("是否确定删除该分组？", "删除操作", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
                if (d == DialogResult.Yes)
                {
                    listBox1.Items.RemoveAt(i);
                    textBox1.Text = "";

                    if (listBox1.Items.Count > 0  )
                    {
                        if (i == listBox1.Items.Count)  //这一句是避免抛出异常
                        {
                            i = 0;
                        }
                        listBox1.SelectedIndex = i;
                        listBox1.Focus();
                    }
                }
            }
        }

        public static void Swap(ref string a, ref string b)
        {
            string c = a;
            a = b;
            b = c;
        }

        /*
         *  上移 和下移 实际上是交换2个数值
         *  上移就是[当前选中]的项和 [上一个项] 对换下值
         *  下移就是[当前选中]的项和 [下一个项] 对换下值
         * 
         */

        private void btnMoveUp_Click(object sender, EventArgs e)
        {
            //[上移]
            string s = textBox1.Text;
            int i = listBox1.SelectedIndex;
            if (i != -1)
            {
                if (i - 1 >= 0)
                {
                    string a = listBox1.Items[i].ToString();
                    string b = listBox1.Items[i - 1].ToString();
                    Swap(ref a, ref b);
                    listBox1.Items[i] = a;
                    listBox1.Items[i - 1] = b;
                    listBox1.SelectedIndex = i - 1;
                }
            }
        }

        private void btnMoveDown_Click(object sender, EventArgs e)
        {
            //[下移]
            string s = textBox1.Text;
            int i = listBox1.SelectedIndex;
            if (i != -1)
            {
                if (i + 1 < listBox1.Items.Count)
                {
                    string a = listBox1.Items[i].ToString();
                    string b = listBox1.Items[i + 1].ToString();
                    Swap(ref a, ref b);
                    listBox1.Items[i] = a;
                    listBox1.Items[i + 1] = b;
                    listBox1.SelectedIndex = i + 1;
                }
            }
        }

        private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            object obj = listBox1.SelectedItem;
            string s = obj != null ? obj.ToString() : ""; //listbox如果没有选中则返回null
            textBox1.Text = s;
            SetupButtonEnabled();
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            //当文本框中的内容和选中的内容一样则不用重命名
            SetupButtonEnabled();
        }


        //用来存放listBox的内容
        string myStr = "";
        private void btnSave_Click(object sender, EventArgs e)
        {
            /*
             * 将listBox的值转换成这种格式 aa,bb,cc,ddd,ee,ff 然后写入文件
             *  ,为分割符，为了避免把逗号号进来， SetupButtonEnabled中设置了如果内容包含,则不能添加
             */
            string s = "";
            StringBuilder sb = new StringBuilder();
            int length = listBox1.Items.Count;
            for (int i = 0; i < length; i++)
            { 
                s = listBox1.Items[i].ToString();
                sb.Append(s + ",");
            }
            s = sb.ToString();
            if (s.EndsWith(","))
                s = s.Substring(0, s.Length - 1);
            myStr = s;
            MessageBox.Show(s);
        }

        private void btnRead_Click(object sender, EventArgs e)
        {
            /*
             * 读取
             * 将这样的 aa,bb,cc,ddd,ee,ff  字符串 转换成字符串数组然后 添加到listBox中
             */
            string[] arr = myStr.Split(new char[] { ',' });
            listBox1.Items.Clear();
            listBox1.Items.AddRange(arr);
        }

        private void listBox1_MouseDown(object sender, MouseEventArgs e)
        {
            //双击删除选中的项 
            int i = listBox1.SelectedIndex;
            if (i != -1)
            {
                if (e.Clicks == 2)
                {
                    listBox1.Items.RemoveAt(i);
                }
            }
        }

        private void 清空_Click(object sender, EventArgs e)
        {   //清空
            listBox1.Items.Clear();
        }

        private void 第一条_Click(object sender, EventArgs e)
        {
            if (listBox1.Items.Count > 0)
            {
                listBox1.SelectedIndex = 0;
                label1.Text = listBox1.SelectedItem.ToString();
            }

            SetupButtonEnabled();
        }

        private void 上一条_Click(object sender, EventArgs e)
        {
            if (listBox1.SelectedIndex - 1 >= 0)
            {
                int i = listBox1.SelectedIndex;
                i--;
                listBox1.SelectedIndex = i;

                label1.Text = listBox1.SelectedItem.ToString();
            }
            SetupButtonEnabled();
        }

        private void 下一条_Click(object sender, EventArgs e)
        {
            if (listBox1.SelectedIndex + 1 <= listBox1.Items.Count)
            {
                int i = listBox1.SelectedIndex;
                i++;
                listBox1.SelectedIndex = i;

                label1.Text = listBox1.SelectedItem.ToString();
            }
            SetupButtonEnabled();
        }

        private void 最后一条_Click(object sender, EventArgs e)
        {
            if ( listBox1.Items.Count >0)
            {
                listBox1.SelectedIndex = listBox1.Items.Count - 1;
                label1.Text = listBox1.SelectedItem.ToString();
            }
            SetupButtonEnabled();
        }

        private void 查找内容_Click(object sender, EventArgs e)
        {
            /*精确搜索*/
            string s = textBox1.Text;
            int i = listBox1.Items.IndexOf(s);   // int i = listBox1.FindStringExact(s);
            if (i != -1)
            {
                listBox1.SelectedIndex = i;
            }
            else
            {
                MessageBox.Show("列表中没有此项");
            }
        }

        private void 模糊查询_Click(object sender, EventArgs e)
        {
            //模糊查询  只要项目包含关键字就行
            string s = textBox1.Text;
            bool b = false;
            for (int i = 0; i < listBox1.Items.Count; i++)
            {
                b = false;
                string x = listBox1.Items[i].ToString();
                if (x.Contains(s))
                {
                    listBox1.SelectedIndex = i;
                    b = true;
                    break;
                }
            }
            if (b == false)
            {
                MessageBox.Show("列表中没有此项");
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            listBox1.SelectedIndex = -1;
        }
    }
}