You can add CRLF to your text to break it to multiple lines. The cells height will adjust to fit it.
Another option is to add Labels instead of strings. You can then set the label height and set word wrap:
Dim lbl As Label
lbl.Initialize("")
lbl.Text = "lksj dflkjs dflkjsd lkfjsd flksdj flksd fjlksdf jlsdkf jslkdf jsldkf jslkdf jsldkf "
lbl.PrefHeight = 100
Dim jlbl As JavaObject = lbl
jlbl.RunMethod("setWrapText", Array As Object(True))
row(0) = lbl
tv1.Items.Add(row)