How to throw good exceptions?

Question

I heard you should never throw a string because there is a lack of information and you\'ll catch exceptions you dont expect to catch. What are good practice for throwing exc

Answer 1

For a current project, we thought about the appropriate action that could be taken by the main program loop. The basic program accepts XML messages, and saves the information into a database (with a fair amount of processing in between).

1. Data errors that indicate something wrong the input. Appropriate action is to save the message to a log directory but not process it.
2. Infrastructure errors that indicate some subcomponent (like the input queue, an SQL database, a JNI library) is malfunctioning. Sleep for a few minutes then reconnect.
3. Configuration errors that indicate some aspect configuration is unworkable. Exit the program.

The first item is a checked exception, since we considered data checking to be part of a method's interface. The others are unchecked since the main loop cannot know the implementations of subcomponents, e.g. an implementation may use an SQL database, or may simply persist data in memory -- the caller doesn't need to know.