Set ListBox Item multi selected

Hi,
I'd like to select ListBox Items by using any text. I mean like below
For example,
Text1.Text = "Item1, Item3, Item5"
ListBox's Items are Item1, Item2, Item3, Item4, Item5.
Selected ListBox Items will be Item1, Item3 and Item5.
Here, I try to find the build-in function that count ',' in any string. How to code?

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