public synchronized Long generateId() {
        if (sequenceBlock == null || !sequenceBlock.hasNext()) {
            sequenceBlock = allocateSequenceBlock();
        }
        return sequenceBlock.next();
    }
public synchronized Long generateId ( ) { if ( sequenceBlock == null || ! sequenceBlock . hasNext ( ) ) { sequenceBlock = allocateSequenceBlock ( ) ; } return sequenceBlock . next ( ) ; }
Return the next number in the sequence.

@return the next number in the sequence