1. Types of Exceptions
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2. Objectives
On completion of this period, you would be able to
learn:
• Exception hierarchy
• Types of exceptions
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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
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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)
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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
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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
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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
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8. Type of Exceptions
• There are two types of exceptions in Java
• Unchecked exceptions
• Checked exceptions
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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
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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
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11. Unchecked Exceptions Examples
Table 46.1 Unchecked Exception
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12. Checked Exceptions Examples
Table 46.2 Checked Exception
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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
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14. Quiz
1. Which exceptions types are not expected to be
caught under normal circumstances by your
program
A. Error
B. Exceptions
C. None
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15. Frequently Asked Questions
1. Explain about the various types of Exceptions
2. List out the various checked and unchecked
exceptions
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