Types of exceptions
- 1. Types of Exceptions http://improvejava.blogspot.in/ 1
- 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
- 4. Exception Hierarchy The following diagram shows exception hierarchy Throwable Error Exception Examples (Out of memory error Stack overflow errors) RuntimeException Examples (ArithmeticException, NullpointerException, Fig. 46.1 Exception hierarchy IndexOutofBoundsException) 4 http://improvejava.blogspot.in/
- 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
- 11. Unchecked Exceptions Examples Table 46.1 Unchecked Exception http://improvejava.blogspot.in/ 11
- 12. Checked Exceptions Examples Table 46.2 Checked Exception http://improvejava.blogspot.in/ 12
- 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