WPF Listbox Collection custom sort - wpf

Question

I have a listbox
DropPrice
MyPrice
Price1
Price2
I want to sort it like this
Price1
Price2
DropPrice
MyPrice
I mean, if there's an item that starts with the sequence "price", it gets priority, else the smallest string should get the priority.
My source code:
var lcv = (ListCollectionView)(CollectionViewSource.GetDefaultView(_itemsSource));
var customSort = new PrioritySorting("price");
lcv.CustomSort = customSort;
internal class PrioritySorting : IComparer
{
private string _text;
public PrioritySorting(string text)
{
_text = text;
}
public int Compare(object x, object y)
{
//my sorting code here
}
}
How can i write compare method. I know, that it can return 1,0 or -1. How can i set priorities.

Answer 1

You just have to check if it starts with "price".
Note that I don't think that ToString() is appropriate; you should rather implement IComparer<T> and strongly type your objects in your listbox.
public int Compare(object x, object y)
{
// test for equality
if (x.ToString() == y.ToString())
{
return 0;
}
// if x is "price" but not y, x goes above
if (x.ToString().StartsWith("Price") && !y.ToString().StartsWith("Price"))
{
return -1;
}
// if y is "price" but not x, y goes above
if (!x.ToString().StartsWith("Price") && y.ToString().StartsWith("Price"))
{
return 1;
}
// otherwise, compare normally (this way PriceXXX are also compared among themselves)
return string.Compare(x.ToString(), y.ToString());
}

Answer 2

Here is sample code snippet for IComparer.
private class sortYearAscendingHelper : IComparer
{
int IComparer.Compare(object a, object b)
{
car c1=(car)a;
car c2=(car)b;
if (c1.year > c2.year)
return 1;
if (c1.year < c2.year)
return -1;
else
return 0;
}
}
This is more specific to your Question
internal class PrioritySorting : IComparer
{
private string _text;
public PrioritySorting(string text)
{
_text = text;
}
public int Compare(object x, object y)
{
var str1 = x as string;
var str2 = y as string;
if (str1.StartsWith("price") )
{
if (str2.StartsWith("price"))
return 0;
return 1;
}
return -1;
}
}