从文件加载列表框 [英] Loading a listbox from a file

问题描述

这是我第一次创建一个C＃程序，所以我很抱歉，如果这个问题似乎基本。我有我的设计形式在3个列表框以及3个按钮，我想项目列表加载到每个文本框中当我点击相应的按钮，列表框。有人可以教我如何做到这一点。

This is my first time creating a C# program so I apologize if this question seems basic. I have 3 list boxes on my design form along with 3 buttons I'd like to load a list of item into each text box when I click the corresponding button for the listbox. can someone instruct me on how to do this.

推荐答案

阿巴斯已经给了你足够的答案，但有几个问题有了它，所以我想我会添加自己的反应。问题：

Abbas has given you a sufficient answer, but there are a couple of problems with it, so I thought I would add my own response. The issues:

1. 流（任何实现的IDisposable ）后需要被关闭你与他们完成。您可以通过手动调用的Dispose（）或包裹在使用块中的对象的创建做到这一点。


2. 您不应该由一个像，在情况下将项目添加到列表框中选择一个有大量的物品。这将导致性能下降，并在列表框中会闪烁，因为它更新添加每个项目后/重绘。

1. Streams (anything that implements IDisposable) need to be closed after you're done with them. You can do this by manually calling Dispose() or by wrapping the creation of the object in a using block.
2. You shouldn't add items to the list box one by one like that in case there are a large number of items. This will cause poor performance and the list box will flicker as it updates/redraws after each item is added.

我会做这样的事情这样的：

I would do something like this:

using System.IO;
// other includes

public partial class MyForm : Form
{
    public MyForm()
    {
        // you can add the button event 
        // handler in the designer as well
        someButton.Click += someButton_Click;
    }

    private void someButton_Click( object sender, EventArgs e )
    {
        PopulateList( "some file path here" );
    }

    private void PopulateList( string filePath )
    {
        var items = new List<string>();
        using( var stream = File.OpenRead( filePath ) )  // open file
        using( var reader = new TextReader( stream ) )   // read the stream with TextReader
        {
            string line;

            // read until no more lines are present
            while( (line = reader.ReadLine()) != null )
            {
                items.Add( line );
            }
        }

        // add the ListBox items in a bulk update instead of one at a time.
        listBox.AddRange( items );
    }
}

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