I feel a little sad today, when I prepared the essay exam, I found some mistakes of english grammar and type in, including specified a different method name than the actual name(parseSearchString() vs.parseSearchCriteria()), in my design choice. However, I have uploaded my assignment before I checked out these mistakes. I am afraid that these mistakes would let me lost some scores. Anyway, I must go aheard to take the essay exam without any choice, any then waiting for the result. Just posting this to remind you guy to check the everything of your assignment carefully before uploading!