将项目添加到列表视图并过滤现有项目

时间：2014-02-08 08:00:09

标签： c# winforms list listview

我正在制作一个计算学生成绩的程序，看看该学生是否是一名荣誉学生。问题是只添加了第一名荣誉学生的名单。属于第二和第三的其他人不再显示。我一直在努力解决这个问题近2天，我仍然无法找到解决这个问题的方法。

List<int> clsid = new List<int>(){2,3,5};
int g = clsid.Count();
List<int> temp_rank1 = new List<int>();
List<int> temp_rank2 = new List<int>();
List<int> temp_rank3 = new List<int>();
//get the student id
foreach (int fr in clsid)
{
 conek.OPEN("select stud_id from class_info where class_id = '"+fr+"' and tmp_gr1 >= 88");
 while (conek.reader.Read())
  {
   temp_rank1.Add(conek.reader.GetInt32(0));
  }
  conek.CLOSE();
 conek.OPEN("select stud_id from class_info where class_id = '" + fr + "' and tmp_gr1 >=85");
 while (conek.reader.Read())
 {
 temp_rank2.Add(conek.reader.GetInt32(0));
 }
 conek.CLOSE();
 conek.OPEN("select stud_id from class_info where class_id = '" + fr + "' and tmp_gr1 >= 83 ");
 while (conek.reader.Read())
 {
  temp_rank3.Add(conek.reader.GetInt32(0));
 }
 conek.CLOSE();
}

如果同一student_id的总数等于g的主题总数，则获取学生ID。

var tmp1 = temp_rank1.GroupBy(n => n).Where(n => n.Count() == g).Select(n => n.Key);
 if (tmp1.Count() >= 1)
   {
    foreach (var gh in tmp1)
    {
    rank1.Add(gh);
    }
   }
var tmp2 = temp_rank2.GroupBy(n => n).Where(n => n.Count() == g).Select(n => n.Key);
 if (tmp2.Count() >= 1)
    {
     foreach (var gh in tmp2)
     {
      rank2.Add(gh);
     }
    }
var tmp3 = temp_rank3.GroupBy(n => n).Where(n => n.Count() == g).Select(n => n.Key);
 if (tmp3.Count() >= 1)
    {
     foreach (var gh in tmp3)
     {
      rank3.Add(gh);
     }
    }

为第一个荣誉学生

nye.SubItems.Add("First Honor");
listView1.Items.Add(nye);
int yt = 0;
foreach (int fgd in idr1)
{
if(rcs1[yt] >= 90){
ListViewItem gtb = new ListViewItem();
conek.OPEN("select concat(l_name,', ',f_name,' ',ucase(substring(m_name,1,1)),'.') from students where stud_id = '"+fgd+"' ");
while (conek.reader.Read())
 {
  gtb.SubItems.Add(conek.reader.GetString(0));
 }
 conek.CLOSE();
 foreach (int gfad in clsid)
  {
   conek.OPEN("select tmp_gr1 from class_info where class_info.stud_id = '" + fgd + "' and class_id = '" + gfad + "' ");
   while (conek.reader.Read())
   {                        
   gtb.SubItems.Add(Math.Round(conek.reader.GetDouble(0),2).ToString());
   }
   conek.CLOSE();
  }
  gtb.SubItems.Add(Math.Round(rcs1[yt],2).ToString());
  yt++;
  listView1.Items.AddRange(new ListViewItem[] { gtb });
 }
}

为第二荣誉学生

listView1.Items.Add("");
ListViewItem nyek = new ListViewItem();
nyek.SubItems.Add("Second Honor");
listView1.Items.Add(nyek);
int yet = 0;
foreach (int fed in idr2)
{
if(!idr1.Contains(fed))
{
 if (rcs2[yet] >= 88)
 {
  ListViewItem gtbs = new ListViewItem();
  conek.OPEN("select concat(l_name,', ',f_name,' ',ucase(substring(m_name,1,1)),'.') from students where stud_id ='" + fed + "'");
  while (conek.reader.Read())
  {
  gtbs.SubItems.Add(conek.reader.GetString(0));
  }
  conek.CLOSE();
   foreach (int gfa in clsid)
   {
   conek.OPEN("select tmp_gr1 from class_info left join students on class_info.stud_id = students.stud_id where class_info.stud_id = '" + fed + "' and class_id = '" + gfa + "' ");
   while (conek.reader.Read())
   {
    gtbs.SubItems.Add(Math.Round(conek.reader.GetDouble(0), 2).ToString());
   }
  conek.CLOSE();
 }
 gtbs.SubItems.Add(Math.Round(rcs2[yet], 2).ToString());
 yet++;
 listView1.Items.AddRange(new ListViewItem[] { gtbs });
  }
 }
}

为第三荣誉学生

listView1.Items.Add("");
ListViewItem ne = new ListViewItem();
ne.SubItems.Add("Third Honor");
listView1.Items.Add(ne);
int yat = 0;
foreach (int fbv in idr3)
{
if (!idr2.Contains(fbv))
 {
  if (rcs3[yat] >= 85)
  {
  ListViewItem bnb = new ListViewItem();
  conek.OPEN("select concat(l_name,', ',f_name,' ',ucase(substring(m_name,1,1)),'.') from students where stud_id = '" + fbv + "' ");
  while (conek.reader.Read())
  {
  bnb.SubItems.Add(conek.reader.GetString(0));
  }
  conek.CLOSE();
  foreach (int nmj in clsid)
  {
   conek.OPEN("select tmp_gr1 from class_info left join students on class_info.stud_id = students.stud_id where class_info.stud_id = '" + fbv + "' and class_id = '" + nmj + "' ");
   while (conek.reader.Read())
   {
   bnb.SubItems.Add(Math.Round(conek.reader.GetDouble(0), 2).ToString());
   }
  conek.CLOSE();
  }
 bnb.SubItems.Add(Math.Round(rcs3[yat], 2).ToString());
 yat++;
 listView1.Items.AddRange(new ListViewItem[] { bnb });
  }
 }
}

1 个答案:

答案 0 :(得分：0)

你的问题是在foreach循环中你只迭代tmp1：

var tmp1 =    temp_rank1.GroupBy(n => n).Where(n => n.Count() == g).Select(n => n.Key);
if (tmp1.Count() >= 1)
 {
  foreach (var gh in tmp1)
  {
  rank1.Add(gh);
  }
 }
var tmp2 = temp_rank2.GroupBy(n => n).Where(n => n.Count() == g).Select(n => n.Key);
if (tmp2.Count() >= 1)
  {
   foreach (var gh in tmp1)
   {
    rank2.Add(gh);
   }
  }
var tmp3 = temp_rank3.GroupBy(n => n).Where(n => n.Count() == g).Select(n => n.Key);
if (tmp3.Count() >= 1)
  {
   foreach (var gh in tmp1)
   {
    rank3.Add(gh);
   }
}

无论如何，我建议你重构，因为这段代码几乎无法读取和维护。 提取类似代码的方法，使用linq的.Any（）而不是.Count＆gt; = 1并使用.AddRange而不是迭代并使用.Add

实际上你在更多的地方犯了同样的错误，比如第二个荣誉部分：

listView1.Items.Add("");
ListViewItem nyek = new ListViewItem();
nyek.SubItems.Add("Second Honor");
listView1.Items.Add(nyek);
int yet = 0;
foreach (int fed in idr2)
{
if(!idr1.Contains(fed))
{
 if (rcs2[yet] >= 88)
 {
  ListViewItem gtbs = new ListViewItem();
  conek.OPEN("select concat(l_name,', ',f_name,' ',ucase(substring(m_name,1,1)),'.')     from students where stud_id ='" + fed + "'");
  while (conek.reader.Read())
  {
  gtbs.SubItems.Add(conek.reader.GetString(0));
  }
  conek.CLOSE();
   foreach (int gfa in clsid)
   {
   conek.OPEN("select tmp_gr1 from class_info left join students on class_info.stud_id     = students.stud_id where class_info.stud_id = '" + fed + "' and class_id = '" + gfa + "'     ");
   while (conek.reader.Read())
   {
    gtbs.SubItems.Add(Math.Round(conek.reader.GetDouble(0), 2).ToString());
   }
  conek.CLOSE();
 }
 gtbs.SubItems.Add(Math.Round(rcs2[yet], 2).ToString());
 yet++;
 listView1.Items.AddRange(new ListViewItem[] { gtbs });
  }
 }
}

应该是：

listView2.Items.Add("");
ListViewItem nyek = new ListViewItem();
nyek.SubItems.Add("Second Honor");
listView1.Items.Add(nyek);
int yet = 0;
foreach (int fed in idr2)
{
if(!idr2.Contains(fed))
{
 if (rcs2[yet] >= 88)
 {
  ListViewItem gtbs = new ListViewItem();
  conek.OPEN("select concat(l_name,', ',f_name,' ',ucase(substring(m_name,1,1)),'.')     from students where stud_id ='" + fed + "'");
  while (conek.reader.Read())
  {
  gtbs.SubItems.Add(conek.reader.GetString(0));
  }
  conek.CLOSE();
   foreach (int gfa in clsid)
   {
   conek.OPEN("select tmp_gr1 from class_info left join students on class_info.stud_id     = students.stud_id where class_info.stud_id = '" + fed + "' and class_id = '" + gfa + "'     ");
   while (conek.reader.Read())
   {
    gtbs.SubItems.Add(Math.Round(conek.reader.GetDouble(0), 2).ToString());
   }
  conek.CLOSE();
 }
 gtbs.SubItems.Add(Math.Round(rcs2[yet], 2).ToString());
 yet++;
 listView2.Items.AddRange(new ListViewItem[] { gtbs });
  }
 }
}

对于第三个人来说同样的事情......只要仔细看一下你引用第二个列表的第一个列表。

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