使用列表将值从一个类传输到另一个类

Posted 2023-04-11

【中文标题】使用列表将值从一个类传输到另一个类

【英文标题】：Transfer values from one class to another using a list

【发布时间】：2021-11-20 18:58:56

【问题描述】：

我在 Visual Studio 2019 中构建的 winforms 应用程序遇到问题。我的应用程序有 8 个表单，我构建了一个新类，我想在其中保存用户通过列表访问的表单的名称并保存它们在 .txt 文件中。我正在为您提供我正在尝试实现的代码片段。

8 种形式之一的代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SQLite;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Speech.Synthesis;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Delfoi_Tourist_Guide

    public partial class Welcome : Form
    
        SQLiteConnection connection;
        private SpeechSynthesizer speech = new SpeechSynthesizer();
        public Welcome()
        
            InitializeComponent();
            User_History.HistList.Add(this.Name);
            User_History.SaveHistory();
        

        private void Welcome_Load(object sender, EventArgs e)
        
            String conn = "Data Source=Delfoidb1.db;Version=3";
            connection = new SQLiteConnection(conn);
            connection.Open(); //or Create Database
        

        private void Timer1_Tick(object sender, EventArgs e)
        
            label1.Show();
            label2.Show();
            button1.Visible = true;
            button2.Visible = true;
            timer2.Enabled = true;
            timer1.Enabled = false;
        

        private void button1_Click(object sender, EventArgs e)
        
            if (speech.State == SynthesizerState.Speaking)
            
                speech.Pause();
            
            Form2 form2 = new Form2();
            form2.Show();
            this.Visible = false;
        

        private void button6_Click(object sender, EventArgs e)
        
            Application.Exit();
        

        private void timer2_Tick(object sender, EventArgs e)
        
            speech.SelectVoice("Microsoft Stefanos");
            speech.SpeakAsync(label2.Text);
            timer2.Enabled = false;
        

        private void button2_Click(object sender, EventArgs e)
        
            if (speech.State == SynthesizerState.Speaking)
            
                speech.Pause();
            
            Form8 form8 = new Form8();
            form8.Show();
            this.Visible = false;
        

        private void aboutToolStripMenuItem1_Click(object sender, EventArgs e)
        
            MessageBox.Show("Developed by Ανδρέας Κρεούζος(ΜΠΠΛ20040) and Δημήτρης Γιογάκης(ΜΠΠΛ20008)");
        

        private void helpToolStripMenuItem_Click(object sender, EventArgs e)
        
            //Implement try - catch to avoid exception specifically for url error
            try
            
                Help.ShowHelp(this, "_tmphhp/Delfoi_Tourist_Guide_Help.chm", HelpNavigator.KeywordIndex, "Topic 1");
            
            catch (Exception exception)
            
                MessageBox.Show(exception.ToString());
            
        

        private void aboutToolStripMenuItem_Click(object sender, EventArgs e)
        
            if (speech.State == SynthesizerState.Speaking)
            
                speech.Pause();
            
            Welcome welcome = new Welcome();
            welcome.Show();
            this.Visible = false;
        

        private void έξοδοςToolStripMenuItem_Click(object sender, EventArgs e)
        
            Application.Exit();
        
    

将数据保存为txt的单独类的代码

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Delfoi_Tourist_Guide

    public static class User_History
    
        public static List<string> HistList = new List<string>();

        public static void SaveHistory()
        
            SaveFileDialog saveFileDialog = new SaveFileDialog();
            if (saveFileDialog.ShowDialog() == DialogResult.OK)
            
                string path = saveFileDialog.FileName;
                StreamWriter sw = new StreamWriter(path);
                sw.WriteLine(HistList);
                sw.Close();
            
        
    

我的问题是我无法将数据（放置在 InitializeComponent 上）从表单传输到我的班级。我得到了我的 txt 文件，其中没有任何内容。我的数据实际上保存在我的公共静态列表中，但我无法将其传输到我的 User_History 类的其余部分。

关于如何做到这一点的任何想法？？？

【问题讨论】：

如果你想将每个字符串写入文件，你应该遍历列表：foreach (String s in HistList) sw.WriteLine(s); 更短的方法是使用System.IO.File.WriteAllLines(path, HistList);

【参考方案1】：

你可以试试这个 SaveHistory() 方法

public static void SaveHistory()

    SaveFileDialog saveFileDialog = new SaveFileDialog();
    if (saveFileDialog.ShowDialog() == DialogResult.OK)
    
        string path = saveFileDialog.FileName;

        using (StreamWriter writer = new StreamWriter(path, false))
        
            foreach (string history in HistList)
            
                writer.WriteLine(history);