Java - where and how should exceptions be used?

Question

I was reading some things about exception handling in Java, to be able to write better code. OK, I admit, I am guilty; I\'ve used too much try-catch{} blocks, I\'ve used

Answer 1

• Using excessive try-catch() has a negative impact on performance?

This sounds like micro optimization and, if this really has a performance impact, you'll have to deal with a lot of bigger performance problems before to face this one.

• Using specific exception types is better? What if i missed to catch one of the possible X types of exceptions that could occur? Frankly, I've heard and use a mere 10% i think of the Java standard exceptions, in 2-3 years. Yes, someone said that if the caller don't know how to deal with the trowed exceptions, he SHOULD NOT HAVE THE RIGHT to call the throwing method. Is that right?

I'm not sure I understood the question but I'd say: "If you don't know what to do with an exception, re-throw it".

• I've read this article of Anders Hejlsberg, saying that checked exceptions are bad. Should that indicate that convenient exception swallowing is advised in some cases?

Hell no. This just means that unchecked exception should be preferred in some cases especially when the user won't know what to do with a checked exception (e.g. SQL exception), or if there is not possible recovery,...

• A picture is worth 1000 words..i guess some examples will help a lot here.

Spring's DataAccessException is a very good example. Check chapter 10. DAO support.