Too many items in listbox?


D

Dale Atkin

I'm coding in VB.net

I've been periodically getting an 'odd' error message that I don't
understand. Normally I can 'pseudo' fix the problem by doing something that
seems entirely unrelated to the problem, but the error keeps popping up
periodically.

Its an out of memory exception, and it pops up here and there. It keeps
complaining that there are 'too many items in list box' or 'too many items
in combo box', etc. The error *sounds* straight forward enough,
unfortunately, I have <<100 items in the list box/combo box in question.

Not sure if it makes a difference, or if it was a bad idea to begin with,
but I've been populating the list with custom objects (not strings). They
aren't all that big objects. Not sure the actual exact size of them, but the
XML file that is generated by the largest is 7kB.

Is this making any sense to anyone? Ringing any bells? (the exception detail
follows)

Dale

System.OutOfMemoryException was unhandled
Message="List box contains too many items."
Source="System.Windows.Forms"
StackTrace:
at System.Windows.Forms.ListBox.NativeAdd(Object item) at
System.Windows.Forms.ListBox.OnHandleCreated(EventArgs e) at
System.Windows.Forms.Control.WmCreate(Message& m) at
System.Windows.Forms.Control.WndProc(Message& m) at
System.Windows.Forms.ListBox.WndProc(Message& m) at
System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at
System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at
System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg,
IntPtr wparam, IntPtr lparam) at
System.Windows.Forms.UnsafeNativeMethods.IntCreateWindowEx(Int32 dwExStyle,
String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32 y,
Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, HandleRef
hInst, Object pvParam) at
System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 dwExStyle,
String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32 y,
Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, HandleRef
hInst, Object pvParam) at
System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) at
System.Windows.Forms.Control.CreateHandle() at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl() at
System.Windows.Forms.Control.WmShowWindow(Message& m) at
System.Windows.Forms.Control.WndProc(Message& m) at
System.Windows.Forms.ScrollableControl.WndProc(Message& m) at
System.Windows.Forms.ContainerControl.WndProc(Message& m) at
System.Windows.Forms.Form.WmShowWindow(Message& m) at
System.Windows.Forms.Form.WndProc(Message& m) at
System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at
System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at
System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg,
IntPtr wparam, IntPtr lparam) at
System.Windows.Forms.UnsafeNativeMethods.IntCreateWindowEx(Int32 dwExStyle,
String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32 y,
Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, HandleRef
hInst, Object pvParam) at
System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 dwExStyle,
String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32 y,
Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, HandleRef
hInst, Object pvParam) at
System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) at
System.Windows.Forms.Control.CreateHandle() at
System.Windows.Forms.Form.CreateHandle() at
System.Windows.Forms.Control.get_Handle() at
System.Windows.Forms.Form.SetVisibleCore(Boolean value) at
System.Windows.Forms.Control.Show() at
AnatomyAlive.frmMain.frmMain_Load(Object sender, EventArgs e) in
E:\Users\UCVM Student\Documents\Visual Studio
2008\Projects\AnatomyAlive\AnatomyAlive\MDIParent1.vb:line 74 at
System.EventHandler.Invoke(Object sender, EventArgs e) at
System.Windows.Forms.Form.OnLoad(EventArgs e) at
System.Windows.Forms.Form.OnCreateControl() at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl() at
System.Windows.Forms.Control.WmShowWindow(Message& m) at
System.Windows.Forms.Control.WndProc(Message& m) at
System.Windows.Forms.ScrollableControl.WndProc(Message& m) at
System.Windows.Forms.ContainerControl.WndProc(Message& m) at
System.Windows.Forms.Form.WmShowWindow(Message& m) at
System.Windows.Forms.Form.WndProc(Message& m) at
System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at
System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at
System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg,
IntPtr wparam, IntPtr lparam) at
System.Windows.Forms.UnsafeNativeMethods.SendMessage(HandleRef hWnd, Int32
msg, Int32 wParam, Int32 lParam) at
System.Windows.Forms.Form.SetVisibleCore(Boolean value) at
System.Windows.Forms.Control.set_Visible(Boolean value) at
System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32
reason, ApplicationContext context) at
System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason,
ApplicationContext context) at
System.Windows.Forms.Application.Run(ApplicationContext context) at
Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
at
Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
at
Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[]
commandLine) at AnatomyAlive.My.MyApplication.Main(String[] Args) in
17d14f5c-a337-4978-8281-53493378c1071.vb:line 81 at
System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) at
System.AppDomain.nExecuteAssembly(Assembly assembly, String[] args) at
System.Runtime.Hosting.ManifestRunner.Run(Boolean checkAptModel) at
System.Runtime.Hosting.ManifestRunner.ExecuteAsAssembly() at
System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext
activationContext, String[] activationCustomData) at
System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext
activationContext) at System.Activator.CreateInstance(ActivationContext
activationContext) at
Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssemblyDebugInZone()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at
System.Threading.ExecutionContext.Run(ExecutionContext executionContext,
ContextCallback callback, Object state) at
System.Threading.ThreadHelper.ThreadStart()
InnerException:
 
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D

Dale Atkin

Apparently I should Google a little harder before posting... I solved the
problem.

Apparently, if the .ToString function returns a null value, you'll get this
message. -- Solution Make sure .ToString doesn't return a null.

No idea why this would give a 'Too many items in listbox' error though (as
opposed to something more descriptive).

Dale

Dale Atkin said:
I'm coding in VB.net

I've been periodically getting an 'odd' error message that I don't
understand. Normally I can 'pseudo' fix the problem by doing something
that seems entirely unrelated to the problem, but the error keeps popping
up periodically.

Its an out of memory exception, and it pops up here and there. It keeps
complaining that there are 'too many items in list box' or 'too many items
in combo box', etc. The error *sounds* straight forward enough,
unfortunately, I have <<100 items in the list box/combo box in question.

Not sure if it makes a difference, or if it was a bad idea to begin with,
but I've been populating the list with custom objects (not strings). They
aren't all that big objects. Not sure the actual exact size of them, but
the XML file that is generated by the largest is 7kB.

Is this making any sense to anyone? Ringing any bells? (the exception
detail follows)

Dale

System.OutOfMemoryException was unhandled
Message="List box contains too many items."
Source="System.Windows.Forms"
StackTrace:
at System.Windows.Forms.ListBox.NativeAdd(Object item) at
System.Windows.Forms.ListBox.OnHandleCreated(EventArgs e) at
System.Windows.Forms.Control.WmCreate(Message& m) at
System.Windows.Forms.Control.WndProc(Message& m) at
System.Windows.Forms.ListBox.WndProc(Message& m) at
System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32
msg, IntPtr wparam, IntPtr lparam) at
System.Windows.Forms.UnsafeNativeMethods.IntCreateWindowEx(Int32
dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32
x, Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef
hMenu, HandleRef hInst, Object pvParam) at
System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 dwExStyle,
String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32
y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu,
HandleRef hInst, Object pvParam) at
System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) at
System.Windows.Forms.Control.CreateHandle() at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl() at
System.Windows.Forms.Control.WmShowWindow(Message& m) at
System.Windows.Forms.Control.WndProc(Message& m) at
System.Windows.Forms.ScrollableControl.WndProc(Message& m) at
System.Windows.Forms.ContainerControl.WndProc(Message& m) at
System.Windows.Forms.Form.WmShowWindow(Message& m) at
System.Windows.Forms.Form.WndProc(Message& m) at
System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32
msg, IntPtr wparam, IntPtr lparam) at
System.Windows.Forms.UnsafeNativeMethods.IntCreateWindowEx(Int32
dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32
x, Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef
hMenu, HandleRef hInst, Object pvParam) at
System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 dwExStyle,
String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32
y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu,
HandleRef hInst, Object pvParam) at
System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) at
System.Windows.Forms.Control.CreateHandle() at
System.Windows.Forms.Form.CreateHandle() at
System.Windows.Forms.Control.get_Handle() at
System.Windows.Forms.Form.SetVisibleCore(Boolean value) at
System.Windows.Forms.Control.Show() at
AnatomyAlive.frmMain.frmMain_Load(Object sender, EventArgs e) in
E:\Users\UCVM Student\Documents\Visual Studio
2008\Projects\AnatomyAlive\AnatomyAlive\MDIParent1.vb:line 74 at
System.EventHandler.Invoke(Object sender, EventArgs e) at
System.Windows.Forms.Form.OnLoad(EventArgs e) at
System.Windows.Forms.Form.OnCreateControl() at
System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at
System.Windows.Forms.Control.CreateControl() at
System.Windows.Forms.Control.WmShowWindow(Message& m) at
System.Windows.Forms.Control.WndProc(Message& m) at
System.Windows.Forms.ScrollableControl.WndProc(Message& m) at
System.Windows.Forms.ContainerControl.WndProc(Message& m) at
System.Windows.Forms.Form.WmShowWindow(Message& m) at
System.Windows.Forms.Form.WndProc(Message& m) at
System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32
msg, IntPtr wparam, IntPtr lparam) at
System.Windows.Forms.UnsafeNativeMethods.SendMessage(HandleRef hWnd, Int32
msg, Int32 wParam, Int32 lParam) at
System.Windows.Forms.Form.SetVisibleCore(Boolean value) at
System.Windows.Forms.Control.set_Visible(Boolean value) at
System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32
reason, ApplicationContext context) at
System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32
reason, ApplicationContext context) at
System.Windows.Forms.Application.Run(ApplicationContext context) at
Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
at
Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
at
Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[]
commandLine) at AnatomyAlive.My.MyApplication.Main(String[] Args) in
17d14f5c-a337-4978-8281-53493378c1071.vb:line 81 at
System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) at
System.AppDomain.nExecuteAssembly(Assembly assembly, String[] args) at
System.Runtime.Hosting.ManifestRunner.Run(Boolean checkAptModel) at
System.Runtime.Hosting.ManifestRunner.ExecuteAsAssembly() at
System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext
activationContext, String[] activationCustomData) at
System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext
activationContext) at System.Activator.CreateInstance(ActivationContext
activationContext) at
Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssemblyDebugInZone()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at
System.Threading.ExecutionContext.Run(ExecutionContext executionContext,
ContextCallback callback, Object state) at
System.Threading.ThreadHelper.ThreadStart()
InnerException:
 
A

Armin Zingler

Dale said:
I'm coding in VB.net

I've been periodically getting an 'odd' error message that I don't
understand. Normally I can 'pseudo' fix the problem by doing
something that seems entirely unrelated to the problem, but the error
keeps popping up periodically.

Its an out of memory exception, and it pops up here and there. It
keeps complaining that there are 'too many items in list box' or 'too
many items in combo box', etc. The error *sounds* straight forward
enough, unfortunately, I have <<100 items in the list box/combo box
in question.
Not sure if it makes a difference, or if it was a bad idea to begin
with, but I've been populating the list with custom objects (not
strings). They aren't all that big objects. Not sure the actual exact
size of them, but the XML file that is generated by the largest is
7kB.
Is this making any sense to anyone? Ringing any bells? (the exception
detail follows)



The only thing I can figure out from here is that you seem to Show the Form
inside Load - which doesn't make sense as Load is raised because Show has
already been called before.
System.Windows.Forms.Control.Show() at
AnatomyAlive.frmMain.frmMain_Load(Object sender, EventArgs e) in
E:\Users\UCVM Student\Documents\Visual Studio
2008\Projects\AnatomyAlive\AnatomyAlive\MDIParent1.vb:line 74 at



Are you using multiple threads?


Armin
 
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D

Dale Atkin

The only thing I can figure out from here is that you seem to Show the
Form
inside Load - which doesn't make sense as Load is raised because Show has
already been called before.

Those were two different forms. MDIParent, calls Show on a child form during
its load event (default behaviour if certain start up conditions are met, so
that the user isn't presented with a blank screen).
Are you using multiple threads?

Nope.

In case anyone reads this and misses the other response sent at the same
time. I tracked the problem down. If "ToString" on the class I'm adding to
the listbox returns "Nothing", the error will show up. I modified "ToString"
so that it will always return something. Still no idea why this triggers the
error the way it does though.

To replicate the odd error message, try the following, with a button
(Button1) and a combobox (ComboBox1) on a form:

Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
Dim s As New Something
ComboBox1.Items.Add(s)
End Sub
End Class
Public Class Something
Public Overrides Function ToString() As String
Return vbNullString
End Function
End Class

Passing a null string directly, yields a much more intelligent error
message, that tells you exactly what is wrong.

Dale
 

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