Vb Net check if arrayList contains a substring

Question

I am using myArrayList.Contains(myString) and myArrayList.IndexOf(myString) to check if arrayList contains provided string and get its index respectively.

But, How could I check if contains a substring?

Dim myArrayList as New ArrayList()
myArrayList.add("sub1;sub2")
myArrayList.add("sub3;sub4")

so, something like, myArrayList.Contains("sub3") should return True

Any reason you are using an old ArrayList rather than a List(of String)? — Ňɏssa Pøngjǣrdenlarp
– Ňɏssa Pøngjǣrdenlarp, Commented Mar 9, 2016 at 16:09
yes, because I am currently using some old functions that return an ArrayList. However, no problem to turn into List. Then, same question for Lists. Thanks — Jaume
– Jaume, Commented Mar 9, 2016 at 16:14

Steve · Accepted Answer · 2016-03-09 16:18:04Z

2

Well you could use the ArrayList to search for substrings with

Dim result = myArrayList.ToArray().Any(Function(x) x.ToString().Contains("sub3"))

Of course the advice to use a strongly typed List(Of String) is absolutely correct.

answered Mar 9, 2016 at 16:18

Steve

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T.S. · Accepted Answer · 2016-03-09 16:55:24Z

1

As far as your question goes, without discussing why do you need ArrayList, because array list is there only for backwards compatibility - to select indexes of items that contain specific string, the best performance you will get here

Dim indexes As New List(Of Integer)(100)

For i As Integer = 0 to myArrayList.Count - 1
    If DirectCast(myArrayList(i), String).Contains("sub3") Then
        indexes.Add(i)
    End If
Next

Again, this is if you need to get your indexes. In your case, ArrayList.Contains - you testing whole object [string in your case]. While you need to get the string and test it's part using String.Contains

If you want to test in non case-sensitive manner, you can use String.IndexOf

edited Mar 9, 2016 at 16:55

answered Mar 9, 2016 at 16:41

T.S.

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