Java does not have an Eval. You would have to either parse it and perform actions logically, or you would have to create a class "on the fly", either with BCEL (Google that) or by generating and then compiling code, or you can look into the scripting engine support in 1.6 (I.E. Google "Rhino").
Dim Adapter As New OleDbDataAdapter
Dim Command As New OleDbCommand
Dim xFrom As String = dtpFrom.Value.ToString.Substring(0, dtpFrom.Value.ToString.IndexOf(" "))
Dim xTo As String = dtpTo.Value.ToString.Substring(0, dtpTo.Value.ToString.IndexOf(" "))
sqlQuery = MainQuery ...