Exception

Exception happens because of something has not gone according to the plans, for example a resource i busy, or format of given parameter is not right or you are trying to put too many members inside an array or access a member that does not exist.

• Return codes are expected, exceptions are not.
• Error class is used for irecoverable errors. No catching, handling or declaring of errors are allowed.
• Runtime or unchecked exceptions can be fatal. Catching or handling of are allowed but not needed, the system takes care of it automatically.
• Checked exception. catching, handling or declaring of are mandatory.
• Finally is called after try and all catch blocks are passed, do not matter it any exception caught.
• Only way to make sure finally is not called is to call System.exit(0) method.

Runtime Exceptions

• ArithmeticException
• ArrayIndexOutOfBoundsException
• ClassCastException
• IllegalArgumentException
• NullPointerException
• NumberFormatException

Checked Exceptions

• FileNotFoundException
• IOException

Errors

• ExceptionInInitializerError
• StackOverflowError
• NoClassDefFoundError