Java – Move a player to another team, with players stored in one arraylist and teams in another using java

Store the stores on disk. I would recommend using a database but for the small amount of data xml would do fine as well. On application start up read this list into a collection. You wouldn't need to create constants for each because you will just be querying the list when you need a store. This will keep you from having to update your code just to add a new store. Also since you are computing distances you will need a list of all the zip codes and their corresponding latitude and longitude so that you can compute the distance between two zipcodes. This could also be stored on disk and most likely will need updating more frequently than your store list. In addition, you could create an admin console that will let you add new stores and update zip codes without having to manually write to the storage mechanism you have chosen.

On the conventional wisdom that states that you should only throw an exception when a condition occurs that you can't handle in your code we tend to focus on the definition of an exceptional condition but ignore the definition of what it means to handle the exception. A process may encounter a exception communicating with a particular node and may handle the exception by redirecting its request to a backup node instead. However, if a call to create an entry in a table fails because of a unique constraint as a result of a value entered by a user the only entity that can truly handle the condition is the user. Therefore this is grounds for throwing an exception as you cannot handle it in your code.

The semantics of your code also matters. Sticking with the example of creating a new user entry; a call to isAvailableUserName(userName) should not throw an exception if the userName already exists in the database whereas a call to createNewUser(userName) probably should. One reason to throw an exception instead of using a return code is that return codes in themselves provide inadequate information and require a lookup table or an enum that then becomes a dependency magnet. Exceptions on the other hand are more descriptive and contain a message, a backtrace, nested exceptions, etc. Exceptions also make your code cleaner. Instead of having lots of nested ifs that exist solely to test conditions, your code can function the way its supposed to and halt execution when a bad thing happens. Robert C. Martin in his book "Clean Code" states that error handling should not obscure the logic of the code. The cleanliness of the code also applies to the caller as return codes force the callers of the code to have to check for errors immediately after the call. Since this can easily be forgotten or ignored, its not a good approach. However, an exception cannot be ignored but must be handled.