listView question

  • Thread starter Thread starter Vanessa
  • Start date Start date
V

Vanessa

With this program I can do one selection,
but upon the second I get an error where
///////////////// is indicated. Please help.

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
namespace WindowsApplication1
{
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.ColumnHeader columnHeader1;
private System.Windows.Forms.ColumnHeader columnHeader2;
private System.Windows.Forms.ListView listView1;
private System.ComponentModel.Container components = null;
public Form1()
{
InitializeComponent();
}
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}
#region Windows Form Designer generated code
private void InitializeComponent()
{
this.textBox1 = new System.Windows.Forms.TextBox();
this.columnHeader1 = new System.Windows.Forms.ColumnHeader();
this.columnHeader2 = new System.Windows.Forms.ColumnHeader();
this.listView1 = new System.Windows.Forms.ListView();
this.SuspendLayout();
//
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(16, 192);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(256, 20);
this.textBox1.TabIndex = 1;
this.textBox1.Text = "";
//
// columnHeader1
//
this.columnHeader1.Text = "number";
this.columnHeader1.Width = 49;
//
// columnHeader2
//
this.columnHeader2.Text = "name";
this.columnHeader2.Width = 186;
//
// listView1
//
this.listView1.Columns.AddRange(new System.Windows.Forms.ColumnHeader[] {
this.columnHeader1,
this.columnHeader2});
this.listView1.GridLines = true;
this.listView1.LabelEdit = true;
this.listView1.Location = new System.Drawing.Point(24, 16);
this.listView1.Name = "listView1";
this.listView1.Size = new System.Drawing.Size(256, 160);
this.listView1.TabIndex = 0;
this.listView1.View = System.Windows.Forms.View.Details;
this.listView1.SelectedIndexChanged += new
System.EventHandler(this.listView1_SelectedIndexChanged);
//
// Form1
//
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(292, 266);
this.Controls.Add(this.textBox1);
this.Controls.Add(this.listView1);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedToolWindow;
this.Name = "Form1";
this.ShowInTaskbar = false;
this.Text = "Form1";
this.Load += new System.EventHandler(this.Form1_Load);
this.ResumeLayout(false);
}
#endregion
[STAThread]
static void Main()
{
Application.Run(new Form1());
}
private void listView1_SelectedIndexChanged(object sender, EventArgs e)
{
ListView.SelectedListViewItemCollection contents =
this.listView1.SelectedItems;
textBox1.Text = contents[0].SubItems[1].Text;/////////////////////error
}
private void Form1_Load(object sender, System.EventArgs e)
{
string [ ] show0 = new string [] {"one","two","three","four"};
string [ ] show1 = new string [] {"ene","mene","mane","moo"};
for (int i = 0; i<show0.Length;i++)
{
ListViewItem listItem = new ListViewItem(show0);
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
namespace WindowsApplication1
{
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.ColumnHeader columnHeader1;
private System.Windows.Forms.ColumnHeader columnHeader2;
private System.Windows.Forms.ListView listView1;
private System.ComponentModel.Container components = null;
public Form1()
{
InitializeComponent();
}
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}
#region Windows Form Designer generated code
private void InitializeComponent()
{
this.textBox1 = new System.Windows.Forms.TextBox();
this.columnHeader1 = new System.Windows.Forms.ColumnHeader();
this.columnHeader2 = new System.Windows.Forms.ColumnHeader();
this.listView1 = new System.Windows.Forms.ListView();
this.SuspendLayout();
//
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(16, 192);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(256, 20);
this.textBox1.TabIndex = 1;
this.textBox1.Text = "";
//
// columnHeader1
//
this.columnHeader1.Text = "number";
this.columnHeader1.Width = 49;
//
// columnHeader2
//
this.columnHeader2.Text = "name";
this.columnHeader2.Width = 186;
//
// listView1
//
this.listView1.Columns.AddRange(new System.Windows.Forms.ColumnHeader[] {
this.columnHeader1,
this.columnHeader2});
this.listView1.GridLines = true;
this.listView1.LabelEdit = true;
this.listView1.Location = new System.Drawing.Point(24, 16);
this.listView1.Name = "listView1";
this.listView1.Size = new System.Drawing.Size(256, 160);
this.listView1.TabIndex = 0;
this.listView1.View = System.Windows.Forms.View.Details;
this.listView1.SelectedIndexChanged += new
System.EventHandler(this.listView1_SelectedIndexChanged);
//
// Form1
//
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(292, 266);
this.Controls.Add(this.textBox1);
this.Controls.Add(this.listView1);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedToolWindow;
this.Name = "Form1";
this.ShowInTaskbar = false;
this.Text = "Form1";
this.Load += new System.EventHandler(this.Form1_Load);
this.ResumeLayout(false);
}
#endregion
[STAThread]
static void Main()
{
Application.Run(new Form1());
}
private void listView1_SelectedIndexChanged(object sender, EventArgs e)
{
ListView.SelectedListViewItemCollection contents =
this.listView1.SelectedItems;
textBox1.Text = contents[0].SubItems[1].Text;/////////////////////error
}
private void Form1_Load(object sender, System.EventArgs e)
{
string [ ] show0 = new string [] {"one","two","three","four"};
string [ ] show1 = new string [] {"ene","mene","mane","moo"};
for (int i = 0; i<show0.Length;i++)
{
ListViewItem listItem = new ListViewItem(show0);
listItem.SubItems.Add(show1);
listView1.Items.Add(listItem);
}
}
}
}
listItem.SubItems.Add(show1);
listView1.Items.Add(listItem);
}
}
}
}
 
The error is because an event is firing with nothing in the SelectedItems...
so trying to access contents[0] fails because there is nothing in contents.

Its a bit strange that there is an event fired with no selected items - it
seems that, when you click on a 2nd different item (without the shift key -
i.e. not making a multi selection), internally the listbox selection is
cleared, causing the event to fire with SelectedItems containing nothing,
before the 2nd item is added to the SelectedItems and the event is fired
again.

You should always protect against there being no selection anyway,
especially in a multiselect listbox - i.e. something like this:

if (contents.Count > 0)
textBox1.Text = contents[0].SubItems[1].Text;
else
textBox1.Text = "(Nothing)";


Cheers,
Pete Beech


Vanessa said:
With this program I can do one selection,
but upon the second I get an error where
///////////////// is indicated. Please help.

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
namespace WindowsApplication1
{
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.ColumnHeader columnHeader1;
private System.Windows.Forms.ColumnHeader columnHeader2;
private System.Windows.Forms.ListView listView1;
private System.ComponentModel.Container components = null;
public Form1()
{
InitializeComponent();
}
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}
#region Windows Form Designer generated code
private void InitializeComponent()
{
this.textBox1 = new System.Windows.Forms.TextBox();
this.columnHeader1 = new System.Windows.Forms.ColumnHeader();
this.columnHeader2 = new System.Windows.Forms.ColumnHeader();
this.listView1 = new System.Windows.Forms.ListView();
this.SuspendLayout();
//
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(16, 192);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(256, 20);
this.textBox1.TabIndex = 1;
this.textBox1.Text = "";
//
// columnHeader1
//
this.columnHeader1.Text = "number";
this.columnHeader1.Width = 49;
//
// columnHeader2
//
this.columnHeader2.Text = "name";
this.columnHeader2.Width = 186;
//
// listView1
//
this.listView1.Columns.AddRange(new System.Windows.Forms.ColumnHeader[] {
this.columnHeader1,
this.columnHeader2});
this.listView1.GridLines = true;
this.listView1.LabelEdit = true;
this.listView1.Location = new System.Drawing.Point(24, 16);
this.listView1.Name = "listView1";
this.listView1.Size = new System.Drawing.Size(256, 160);
this.listView1.TabIndex = 0;
this.listView1.View = System.Windows.Forms.View.Details;
this.listView1.SelectedIndexChanged += new
System.EventHandler(this.listView1_SelectedIndexChanged);
//
// Form1
//
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(292, 266);
this.Controls.Add(this.textBox1);
this.Controls.Add(this.listView1);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedToolWindow;
this.Name = "Form1";
this.ShowInTaskbar = false;
this.Text = "Form1";
this.Load += new System.EventHandler(this.Form1_Load);
this.ResumeLayout(false);
}
#endregion
[STAThread]
static void Main()
{
Application.Run(new Form1());
}
private void listView1_SelectedIndexChanged(object sender, EventArgs e)
{
ListView.SelectedListViewItemCollection contents =
this.listView1.SelectedItems;
textBox1.Text = contents[0].SubItems[1].Text;/////////////////////error
}
private void Form1_Load(object sender, System.EventArgs e)
{
string [ ] show0 = new string [] {"one","two","three","four"};
string [ ] show1 = new string [] {"ene","mene","mane","moo"};
for (int i = 0; i<show0.Length;i++)
{
ListViewItem listItem = new ListViewItem(show0);
listItem.SubItems.Add(show1);
listView1.Items.Add(listItem);
}
}
}
}
Click to expand...
 
Thank you Pete,

Your suggestion solved that one.

Can you also input into a listView? I do not see a "Read Only = true/false"
in with the Properties.
 
Setting LabelEdit to true allows the first column (the 'label') to be
edited. (In the example, LabelEdit is set to true.) To edit, you can single
click an item that is already selected.

Patrick de Ridder said:
Thank you Pete,

Your suggestion solved that one.

Can you also input into a listView? I do not see a "Read Only = true/false"
in with the Properties.


Pete Beech said:
You should always protect against there being no selection anyway,
especially in a multiselect listbox - i.e. something like this:

if (contents.Count > 0)
textBox1.Text = contents[0].SubItems[1].Text;
else
textBox1.Text = "(Nothing)";
Click to expand...
Click to expand...
 
Pete,
Thanks for responding. Guess it cannot be done.
Don't see much use for just being able to edit
the first column and not the orthers.
 
Is it possible to have a listview with checkboxes that allows the user
to
1. select an entry (mouse click) but not have the box checked
2. and vice-versa ie check a box without selecting that entry.

The only way I can do the above is if I select a different entry by
moving the cursor up and down using the keyboard. If I click on an
entry then the checkbox is also selected (FullRowSelect is set to
false).

Am I using the right control? Should I be using 2 listboxes side by
side - which seems somewhat daft. Or do maybe bodge it - just thought
: maybe I can check a select event against a checkedbox event (not
sure if there is one) ie if both called then call the checkedbox event
again to toggle it back.
 
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