@ccyjoshua it seems your solution has a fixed bucket size. The efficiency will drop quickly when the size is increasing. So it's better to adjust (increasing or decreasing) the bucket size on the fly based on a load factor. For example, the LF = 0.75, if the size of the HashMap > 0.75 * size of Bucket, we should double the size of the bucket. Then cut the bucket by half when size of the HashMap < 0.75 * half size of Bucket.
@chenkai1812 if you are applying for a Mobile Developer type role, I am assuming that you have some experience in the field. If you do not, you can still follow this advice.
Learn by doing: Come up with a basic idea of an app to develop. Define all its requirements, down to the last bit and then think of what is needed to make it workable.
Learn by failing: While you are developing said app, you will have the opportunity to learn what NOT to do and those types of questions are usually asked in interviews.
Publish your app When you make a basic submission of this app, you most probably will have not put any consideration into design patterns, event flow, storage optimization, security, etc. Now, when you publish an app through Google Developer console, you are provided with some insight into what to do write and how. This is very important feedback. If your app gets approved, distribute it and have your friends and family use it. They will give you feedback on the non functional aspects of the app. This information is helpful too.
Obviously, reading from online forums, interview questions for the specific company you are applying to, and last but not the least, books, helps too but these things will help you learn what is exactly expected of you when you start working. Preparing this way will give you a confidence that will be unparalleled and the knowledge to support the confidence.
The Whole Q&A object is child class that parent product (or itemID) class uses.
I believe ArrayList<Items> items; does not belong in this class, but instead it belongs to its parent class for items , which uses this Q&A class. This class keeps a data member for itemID, and will be stored in implicit object first time this classes object is instantiated with appropriate constructor.
Also, all the post Questions and Post Answer function does not need item Id, as it is implied for the same object, once that object contextualized.
(For this Q&A object can and does belong to one unique product ItemId.)
@veeraiah_chowdary Nice start. I think you switched put/post. You should add a way to update the status. Also, you can think of many features for the room and the user that are missing from your design, e.g. price at date, ocean view, etc.