sorting listbox

[LuckyDan]

I have 2 listboxes

the first one is populated by a Oracledatabase and I sorted it by my sql query(order by)

the second must be populated by selecting items from the first one

that's no problem but I want that the second listbox should be sorted also

 

and when i retrieve items from the second i want to put them sorted in the first one

 

do i have to use an array? or are there other means?

[Volte]

You could set the Sorted property to true if you just want simple alphabetic order. If you want a different order, you will need to write a class which derives from IComparer and use it with the Sort method of af an array. An IComparer is just an object which compares two objects and returns whether [Thing A] is less than, equal to, or greater than [Thing B] so it knows where to put it in the array.

 

Note that if you want to use a different IComparer, you will need to use an array to sort it and then add to the listbox.

[LuckyDan]

Thanks but I use a webform and not a windowform

[PlausiblyDamp]

Probably best going with VolteFace's suggestion of putting it in an array and sorting that.

As an aside - if you post a question in the Windows Forms forum people are going to assume the question is about Windows Forms.

[LuckyDan]

thanks it's was my first time I posted a question

have a nice day

[mocella]

For a web-form you can do this:

//GENERIC FUNCTION FOR SORTING A LIST BOX
private void SortListBox(ListBox currList)
{
//COPY THE MEMBERS OF THE LISTBOX INTO AN ARRAY LIST
ArrayList arraylist = new ArrayList();
foreach(ListItem li in currList.Items)
{
arraylist.Add(li);
}
arraylist.Sort(new ListObject(ListObject.Directions.ascending)); //SORT THE LIST - ASCENDING

//REMOVE THE EXISTING ITEMS FROM LISTBOX
currList.Items.Clear(); 

//RE-ADD THE SORTED ITEMS TO THE LISTBOX
for(int i = 0 ; i < arraylist.Count ; i++)
{
currList.Items.Add((ListItem) arraylist[i]);
}
currList.SelectedIndex = -1; //ENSURE NO SELECTED ITEM
	}

	

//*** NEED THIS FOR ARRAY-LIST SORTING: ***
private class ListObject : IComparer
{
public enum Directions : int { ascending = 1, descending = (-1) };
private int direction = (int) ListObject.Directions.ascending;

public ListObject() {}
public ListObject(Directions direction) { 
 this.direction = (int) direction; 
}

public int Compare(object x, object y)
{
string xstring = ((ListItem) x).Text;
string ystring = ((ListItem) y).Text;
return xstring.CompareTo(ystring) * this.direction;
}
}
	//*******************************************[

Edited October 23, 2003 by Volte