如何事先編輯或從列表框中刪除記錄

Question

我的道歉，如果我使用了錯誤的術語，請下跌免費問我澄清如果有什麼似乎在這個問題困惑

我想寫在C＃，做三件事的程序： 加4個文本字段到列表框，編輯在列表框的一個記錄的任何或所有字段，刪除所有4個字段（在一個單一的記錄）

我存儲數據在一個文本文件「test1.txt」中使用StreamWriter編寫文件和StreamReader來讀取它。 香港專業教育學院設法添加記錄，但我沒有得到它刪除或編輯記錄 這是我的代碼如下所示：

string path = "test1.txt"; 
int index = -1;  
public Form1()  
{InitializeComponent();}  

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

private void readFile() 
    {  
     displayEventsBox.Items.Clear(); 
     StreamReader sr = new StreamReader(path); 
     string record = sr.ReadLine(); 
      { 
       displayEventsBox.Items.Add(record);  
       record = sr.ReadLine();  
      }  
     sr.Close(); 
    } 


private void displayEventsBox_SelectedIndexChanged(object sender, EventArgs e) 
    {  
     index = displayEventsBox.SelectedIndex; 
     if (index > -1) 
      {  
       string record = displayEventsBox.Items[index].ToString();  
       char[] delim = { ',' };  
       string[] tokens = record.Split(delim);  
       txtTaskName.Text = tokens[0];  
       txtTaskDescription.Text = tokens[1];  
       txtDateCreated.Text = tokens[2];  
       txtDateCompleted.Text = tokens[3];  
      } 
    } 

private void butAddTask_Click(object sender, EventArgs e) 
    { 
     StreamWriter sw = new StreamWriter(path, true); 
     sw.WriteLine(txtTaskName.Text + "," + txtTaskDescription.Text + "," + txtDateCreated.Text + "," + txtDateCompleted.Text); 
     sw.Close(); 
     readFile(); 
     clearText();} 

private void butEditTask_Click(object sender, EventArgs e) 
    { 
     File.Delete(path);  
     StreamWriter sw = new StreamWriter(path, true);  
     for (int i = 0; i < displayEventsBox.Items.Count; i++)  
      {  
       if (i != index) 
        { 
         sw.WriteLine(displayEventsBox.Items[i].ToString()); 
        } 
       else 
        { 
         sw.WriteLine(txtTaskName.Text + "," + txtTaskDescription.Text + "," + txtDateCreated.Text + "," + txtDateCompleted.Text); 
        } 

      } 

    } 

private void butDeleteTask_Click(object sender, EventArgs e) 
    { 
     File.Delete(path); 
     StreamWriter sw = new StreamWriter(path, true);  
     for (int i = 0; i < displayEventsBox.Items.Count; i++)  
      { 
       if (i != index)// write from listbox  
        { 
         sw.WriteLine(displayEventsBox.Items[i].ToString()); 
        }  

      }  
       sw.Close();  
       readFile();  

    } 

可能有人請幫我找出爲什麼它不會讓我刪除或更新記錄

在情況下，它可以幫助澄清這裏是在代碼 http://collabedit.com/83rev

Answer 1

使用File.ReadAllLines和File.WriteAllLines會讓你的生活更輕鬆。在你的閱讀方法中，File.ReadAllLines應該很簡單。然後在你的刪除方法中，而不是寫入文件，然後更新列表框，我會按照相反的順序進行操作。首先從列表框中刪除該項目（listBox1.Items.Remove(listBox1.SelectedItem);），然後將其餘文件寫入文件File.WriteAllLines(filename, listBox1.Items.Cast<string>());。然後，由於您已經更新了列表框，所以最後不需要撥打readFile()。類似於添加和編輯。

此外，由於沒有其他功能正在調用readFile了，您可以直接將所有代碼直接放入Form1_Load。當表單關閉時，您也可以保存一次。

下面是固定後的功能。

private void Form1_Load(object sender, EventArgs e) { 
     displayEventsBox.Items.AddRange(File.ReadAllLines(path)); 
    } 

    string Format() { 
     return txtTaskName.Text + "," + txtTaskDescription.Text + "," + txtDateCreated.Text + "," + txtDateCompleted.Text; 
    } 

    private void butAddTask_Click(object sender, EventArgs e) { 
     displayEventsBox.Items.Add(Format()); 
    } 

    private void butDeleteTask_Click(object sender, EventArgs e) { 
     displayEventsBox.Items.RemoveAt(displayEventsBox.SelectedIndex); 
    } 

    private void butEditTask_Click(object sender, EventArgs e) { 
     displayEventsBox.Items[displayEventsBox.SelectedIndex] = Format(); 
    } 

    protected override void OnClosing(CancelEventArgs e) { 
     File.WriteAllLines(path, displayEventsBox.Items.Cast<string>()); 
     base.OnClosing(e); 
    } 

Answer 2

就像我說的一切的鏈接，你的問題可能是readfile永遠只能加載一個項目，嘗試

using(StreamReader sr = new StreamReader(path)) 
{ 
    string record; 
    while((record = sr.ReadLine()) != null) 
    { 
     displayEventsBox.Items.Add(record); 
    } 
}  

除此之外，你不應該關心一旦你加載一次就加載。而不是添加一個項目...

只需嘗試以下操作。

string s = txtTaskName.Text + "," + txtTaskDescription.Text + "," 
       + txtDateCreated.Text + "," + txtDateCompleted.Text; 
displayEventsBox.Items.Add(s); 

會有類似的方法進行編輯，刪除等

繼承人當前的方法的細分...

string record = sr.ReadLine();    //read a line 
{           //Open a block that doesn't do much 
    displayEventsBox.Items.Add(record); //Add the item 
    record = sr.ReadLine();    //Read the next item but ignore it 
}           //Close the random block