Java Exceptions (interview 問到囉!!!)

For run time exceptions

• method signature does not need to declare runtime exceptions
• caller to a method that throws a runtime exception is not forced to catch the runtime exception
• Runtime exceptions extend from RuntimeException or Error

Example:

ArithmeticException, IllegalArgumentException, ClassCastException, NullPointerException, IndexOutOfBoundException,

SystemException, NoSuchMethodException.

For checked exceptions:

• method must declare each checked exception it throws
• caller to a method that throws a checked exception must either catch the exception or throw the exception itself
• Checked exceptions extend from Exception

Checked exceptions indicate an exceptional condition from which a caller can conceivably recover. Runtime exceptions indicate a programmatic error from which a caller cannot normally recover.

Checked exceptions force you to catch the exception and to do something about it. You should always catch a checked exception once you reach a point where your code can make a meaningful attempt at recovery. However, it is best not to catch runtime exceptions. Instead, you should allow runtime exceptions to bubble up to where you can see them.