2. Objectives
On completion of this period, you would be able to
learn:
• Exception hierarchy
• Types of exceptions
http://improvejava.blogspot.in/ 2
3. Recap
• In the last class, you have studied about the concept
of multi-catch statements
• We have also written a sample program using multi
catch statements
• A program on finally block was also examined
http://improvejava.blogspot.in/ 3
5. Exception Hierarchy Contd ..
• All exception types are subclasses of the built-in
class Throwable
• Throwable is at the top of the exception class
hierarchy as shown in the Fig 46.1
• Below Throwable are two subclasses that
partition exceptions into two distinct branches,
namely
• Exception
• Error
http://improvejava.blogspot.in/ 5
6. Exception Hierarchy Contd ..
• Exception class is used for exceptional conditions
that user programs should catch
• It is used to create your own custom exception types
• RuntimeException is a subclass of Exception
• It is automatically defined for the programs that you
write
• Includes things such as division by zero and invalid
array indexing
http://improvejava.blogspot.in/ 6
7. Error
• It defines exceptions that are not expected to be
caught under normal circumstances by your
program
• Stack overflow is an example of such an error
http://improvejava.blogspot.in/ 7
8. Type of Exceptions
• There are two types of exceptions in Java
• Unchecked exceptions
• Checked exceptions
http://improvejava.blogspot.in/
9CM604.46 8
9. Unchecked Exceptions
• The compiler does not check to see if a method
handles or throws these exceptions
• Hence the name unchecked
• They need not be included in any method’s throws
list
http://improvejava.blogspot.in/ 9
10. Checked Exceptions
• The compiler checks whether these exceptions were
handled in the method
• That must be included in a method’s throws list
• Compiler error occurs if these exceptions were not
handled by the methods
http://improvejava.blogspot.in/ 10
13. Summary
• All exception types are subclasses of the built-in
class Throwable
• Throwable is at the top of the exception class
hierarchy
• Exception, Error are subclasses of Throwable
• Types of exception
• Unchecked exceptions
• Checked exceptions
http://improvejava.blogspot.in/ 13
14. Quiz
1. Which exceptions types are not expected to be
caught under normal circumstances by your
program
A. Error
B. Exceptions
C. None
http://improvejava.blogspot.in/ 14
15. Frequently Asked Questions
1. Explain about the various types of Exceptions
2. List out the various checked and unchecked
exceptions
http://improvejava.blogspot.in/ 15