我有一个WinForms应用程序,它使用列表框来显示项目列表。当列表框中的项目数量超过150个时,我的应用程序会挂起。这是ListBox控件仅能容纳很少数量项目的属性吗?如果是这样,我想要请求您为此问题提供解决方案。
Thanks, Rakesh.
我有一个WinForms应用程序,它使用列表框来显示项目列表。当列表框中的项目数量超过150个时,我的应用程序会挂起。这是ListBox控件仅能容纳很少数量项目的属性吗?如果是这样,我想要请求您为此问题提供解决方案。
Thanks, Rakesh.
这一切取决于你绑定的内容,如果你要绑定简单的键值对,你可以很容易地即时绑定10k。你可以尝试在循环中添加项目而不是绑定,看看是否有某个项目会使其停顿。
for (int i = 0; i < 10000; i++)
{
listBox1.Items.Add("item:" + i.ToString());
}
您可以根据更大的数据集来支持您的列表框,并使用分页机制,或者您可以添加一个 SizeChanged 事件侦听器,并在达到最大值时禁用添加。
第一个提示,总是...
SuspendLayout();
// fill your lists
ResumeLayout();
第二个提示:尽可能使用 AddRange。
第三,虽然可能有点过头,但是创建自己的ListBox...
public class LimitedListBox : ListBox
{
private int _maxItems = 100;
public LimitedListBox()
{
SetItems(new LimitedObjectCollection(this, _maxItems));
}
public int MaxItems
{
get { return _maxItems; }
set { _maxItems = value; }
}
/// <summary>
/// This is the only bug - no design time support for Items unless
/// you create an editor.
/// </summary>
public new LimitedObjectCollection Items
{
get
{
if (base.Items == null)
{
SetItems(new LimitedObjectCollection(this, _maxItems));
}
return (LimitedObjectCollection) base.Items;
}
}
private void SetItems(ObjectCollection items)
{
FieldInfo info = typeof (ListBox).GetField("itemsCollection",
BindingFlags.NonPublic | BindingFlags.Instance |
BindingFlags.GetField);
info.SetValue(this, items);
}
#region Nested type: LimitedObjectCollection
public class LimitedObjectCollection : ObjectCollection
{
private int _maxItems;
public LimitedObjectCollection(ListBox owner, int maxItems)
: base(owner)
{
_maxItems = maxItems;
}
public LimitedObjectCollection(ListBox owner, ObjectCollection value, int maxItems)
: base(owner)
{
_maxItems = maxItems;
AddRange(value);
}
public LimitedObjectCollection(ListBox owner, object[] value, int maxItems)
: base(owner)
{
_maxItems = maxItems;
AddRange(value);
}
public int MaxItems
{
get { return _maxItems; }
set { _maxItems = value; }
}
public new int Add(object item)
{
if (base.Count >= _maxItems)
{
return -1;
}
return base.Add(item);
}
public new void AddRange(object[] items)
{
int allowed = _maxItems - Count;
if (allowed < 1)
{
return;
}
int length = allowed <= items.Length ? allowed : items.Length;
var toAdd = new object[length];
Array.Copy(items, 0, toAdd, 0, length);
base.AddRange(toAdd);
}
public new void AddRange(ObjectCollection value)
{
var items = new object[value.Count];
value.CopyTo(items, 0);
base.AddRange(items);
}
}
#endregion
}
为什么不要让你把自己的数据库同起来。
int Total = yourarray.GetLength(0);
Then all you have to do is this in your new array.
double [] new = double[Total];
array.copy(Total,new);
Now you have an array thats dynamic. Anytime your database grows it automatically populates the new array.
如果您可以在您的数据库上执行选择计数语句,您可以得到行的总数,然后将其传递给一个字符串。然后您可以使用这个字符串来控制数组。希望这可以帮到您。
当往列表框添加项目时,我刚刚收到了一个“内存不足”的错误提示。问题与项目太多无关。我的代码中有一个错误,列表框中的项目在ToString()方法中返回null。因此,Dot Net的错误提示是错误和令人困惑的。
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