获取列表框项方法返回空值 [英] get listbox items method returns null value

问题描述

我编写了以下方法来获取CheckedListBox Items并进行一些修改，但是它并没有在

I wrote the following method to get CheckedListBox Items and do some modifications, but it doesn''t loop inside the

foreach (object o in lstKeyWordsForSearch.CheckedItems)

，然后返回

and return null value

public List<string> GetKeyWordsFormList()
{
    List<string> words = new List<string>();
    foreach (object o in lstKeyWordsForSearch.CheckedItems)
    {
        string s = o.ToString().ToLower();
        if (s != null)
        {
            string[] separated = s.Split(',');
            string[] arrremove = null;
            frmStopWordList stopWords = new frmStopWordList();
            arrremove = stopWords.getStopWords();
            for (int i = 0; i < separated.Length; i++)
            {
                for (int j = 0; j < arrremove.Length; j++)
                {
                    if (separated[i] == arrremove[j])
                    {
                        separated[i] = "";
                    }
                }
            } // remove stop words
            foreach (string word in separated)
            {
                if (!string.IsNullOrEmpty(word))
                {
                    if (!words.Contains(word))
                    {
                        words.Add(word);
                    }
                }
            }
        }
    }
    return words;
}</string></string></string>

其中lstKeyWordsForSearch声明为CheckedListBox的名称，我从另一个Windows窗体获取该返回值 ，如下所示:

where lstKeyWordsForSearch declared as name of CheckedListBox and I am getting that return value from another windows Form like following:

frmMainForm mainForm = new frmMainForm();
List<string> SearchKeyWords = mainForm.GetKeyWordsFormList();
foreach (string item in SearchKeyWords)
{
    MessageBox.Show(item);
}</string>

但是当我调用 public List< string>时，MessageBox.Show(item);不会显示任何内容.具有相同形式的GetKeyWordsFormList()</string> 方法可以提供输出，但是当我从另一种形式进行调用时，它什么也没有提供.

but MessageBox.Show(item); doesn''t show anything when I call that public List<string> GetKeyWordsFormList()</string> method in the same form it gives output but when I call from another form it gives nothing.

推荐答案

选中的列表框中是否有任何项目?

如果您没有检查任何项目，则foreach将按不进行处理的设计完成

Do you have any items in the checked list box checked?

if you do not have any items checked in it then the foreach would be completing as designed by not processing

这是您的问题:

This is your problem:

frmMainForm mainForm = new frmMainForm();
List SearchKeyWords = mainForm.GetKeyWordsFormList();

在调用"mainForm.GetKeyWordsFromList"之前，您没有调用"frmMainForm.ShowDialog".

You are not calling "frmMainForm.ShowDialog" before you call "mainForm.GetKeyWordsFromList".

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