B4J Question get MySql User's grants

Dim metadata As JavaObject = sql.As(JavaObject).GetFieldJO("connection").RunMethod("getMetaData", Null)
Dim rs As ResultSet = metadata.RunMethod("getTablePrivileges", Array(Null, Null, "*.*"))
Do While rs.NextRow
    For i = 0 To rs.ColumnCount - 1
        Log(rs.GetColumnName(i) & ": " & rs.GetString2(i))
    Next
Loop
rs.Close

Sub Button1_Click
    Dim rs As ResultSet = Sql1.ExecQuery("show grants for current_user")
    Dim dumint As Int = rs.ColumnCount
    Dim dumColName As String = rs.GetColumnName(0)
    Dim dummy As String = rs.GetString2(0)
End Sub

java.sql.SQLException: Before start of result set

Dim cur As ResultSet = SQL.ExecQuery("show grants for current_user")
   
Do While cur.NextRow
        For i = 0 To cur.ColumnCount - 1
            Log(cur.GetColumnName(i) & ": " & cur.GetString2(i))           
        Next       
Loop
cur.Close

Grants for TST_OneTwo@localhost: GRANT USAGE ON *.* TO 'TST_OneTwo'@'localhost'
Grants for TST_OneTwo@localhost: GRANT ALL PRIVILEGES ON `TST_OneTwo`.* TO 'TST_OneTwo'@'localhost'