Error class in Java

Question

I am trying to understand the Error class in Java.

I have a good understanding of the Exception class, but can't find examples of code for the Error class. I've tried searching the web and also the java.sun website, but I'm not finding anything useful to help me understand this better.

How do I use the Error class in programs and where do we have to use that?

Answer 1

You don't use Error in your code.

An Error is a specific kind of Throwable, just as Exception is.

• Throwable is the base class that defines everything that can be thrown.
• Exception is the common case. It is about problems that occur during the execution of your program.
  • RuntimeException is a special case: it's unchecked (i.e. it need not be declared by a method and the compiler doesn't force you to catch it).
• Error is the "rare" case: it signifies problems that are outside the control of the usual application: JVM errors, out of memory, problems verifying bytecode: these are things that you should not handle because if they occur things are already so bad that your code is unlikely to be able to handle it sanely.

You should not attempt to correct the situation that resulted in an Error. You might want to catch it in order to log it and then rethrow it (see the JavaDoc of ThreadDeath for an example on why you need to rethrow it (thanks to @krock for the heads-up)).

There is no other reason to throw any Error (i.e. don't create an Error on your own and throw it, if you think you want to do that, use an Exception or a RuntimeException instead).