Java Exception Handling 面试题与答案

问题 11. Explain the difference between 'throw' and 'throws' in Java.

'throw' is used to explicitly throw an exception, while 'throws' is used in method signature to declare that the method may throw one or more types of exceptions.

问题 12. What is the purpose of the 'NullPointerException' in Java?

The 'NullPointerException' is thrown when attempting to access or modify an object reference that is null.

Example:

String str = null;
int length = str.length(); // This will throw NullPointerException

问题 13. How can you create a custom exception in Java?

To create a custom exception, you need to extend the 'Exception' class or one of its subclasses.

Example:

class CustomException extends Exception { /* constructor and additional code */ }

问题 14. What is the purpose of the 'try' block?

The 'try' block is used to enclose a block of code where exceptions might occur.

Example:

try { /* code that may throw exceptions */ } catch (Exception e) { /* handle exception */ }

问题 15. Can you have multiple 'finally' blocks in a try-catch-finally statement?

No, there can be at most one 'finally' block associated with a 'try-catch' statement.