Hi,
Jon said:
it's not working for me . I add a new item as multi-dimensional like this:
"arrChartList.Add( New ChartItem (Unit,Amount ) ) "
How do I test for existence of ChartItem ?
I tried but no success with :
If Not arrChartList.Contains(ChartItem ( Unit,Amount ) ) Then
arrChartList.Add( New ChartItem (Unit,Amount ) )
End If
When you use the "Contains" method to look an item up, the item you pass
to the Contains method must be a reference to the *same* object stored
in the ArrayList. In other words, the '==' operator must return true.
For a string, you can use a different object with the same value,
because the '==' operator works this way for strings. But for an object,
it doesnt' work.
MyObject obj1 = new MyObject( 3, 4, 5 );
MyObject obj2 = new MyObject( 3, 4, 5 );
obj1 == obj2; // this is false, unless you override the '==' operator to
return a different value.
So... to solve your problem, there are different ways. One is to save a
reference to the ChartItem you create somewhere in your code, and to use
this reference to check if it was added to the ArrayList already, or you
can use a Hashtable and check for the Key rather than for the value
itself. Since the key can be pretty much anything, you can use for
example a string representation of your ChartItem, which makes things
easier.
HTH,
Laurent
