Below piece of code can be used to retrieve next record Id from the table.
staticvoidgetNextRecId(Args _args)
{
//Table that stores record ids details for tables
SystemSequences systemSequences;
//Class that handles Record id generation
SystemSequence systemSequence = newSystemSequence();
;
info(strFmt("%1", tableNum(SalesTable)));
systemSequence.suspendRecIds(tableNum(SalesTable));
info(strFmt("Next record id: %1", systemSequence.reserveValues(1,tableNum(SalesTable))));
systemSequence.removeRecIdSuspension(tableNum(SalesTable));
}