B4J Question How to implement the MidExtract function of B4A in B4J

Sub AppStart (Args() As String)
    Log(MidExtract("Dr. Jim Joe Brown", "Jim", "Brown").Trim)
    Log(MidExtract("Dr. Jim [Joe] Brown", "[", "]"))
End Sub

 Public Sub MidExtract (StringText As String, Start As String, EndAt As String) As String
     Dim i1 As Int = StringText.IndexOf(Start) + Start.Length
    Dim i2 As Int = StringText.IndexOf2(EndAt, i1)
    Return StringText.SubString2(i1, i2)
End Sub