Exceptions in Java can disrupt normal program flow and are divided into checked exceptions which can be recovered from, errors which cannot be recovered from, and unchecked exceptions which usually indicate bugs. There are best practices for exceptions such as never swallowing them, throwing specific exceptions, catching specific subclasses, logging or rethrowing exceptions, and avoiding returns or throws in finally blocks.

1. Exceptions in Java

2. An exception is an event, which occurs
during the execution of a program, that
disrupts the normal flow of the program.

3. Exception Hierarchy
Unchecked
CheckedError

4. Three Kinds of Exceptions
• Checked - subject to the Catch or Specify Requirement.
• Application can recover from it.
• Errors - external to the app, app can’t recover from.
• Hardware or system malfunction.
• Unchecked – not a subject to the Catch or Specify.
• Application cannot recover from it.
• Usually app bugs.

5. Exception is a part of API

6. Basic example

7. What’s Wrong Here ?

8. Basic example in Java 7

9. What else is in Java 7

10. Custom Exception

11. Exceptions in JUnit

12. Exceptions in JUnit

13. Best Practices
• Never swallow the exception in catch block.
• Always throw specific exception.

14. Best Practices
• Catch specific sub-classes.
• Include cause, otherwise stack trace will be lost.

15. Best Practices
• Either log the exception or throw it.
• Never return or throw from finally block.

16. Thank you!