This presentation provide a detailed introduction about Exceptions and Exception Handling in Java.

1. EXCEPTIONS
Exception is an occurrence that alters
the normal program flow.
Program terminates when an exception
is thrown.
To avoid from this, we must handle the
exceptions.
Try block & Catch clause.

2. Normal format of exception
handling
try{
risky code
}catch (Name of Exception){
What to do if an exception is
thrown
}

3. Finally Block
Definitely Executes
Try must be followed by,
1. a catch clause
2. many catch clauses
3. a finally block
4. catch clauses and a finally block
No code between try and catch

4. Exception Class
Java.lang.Exception
All Exceptions are sub classes of
the class Exception
Creating our own Exception by
extending the class Exception
The Keyword throw

5. Exception Hierarchy
Throwable
Exceptions
Runtime
Exception
Interrupted
Exception
Arithmetic
Exception
Errors
Stackoverflaw
Error
Assertion
Error

6. Errors
Errors represent unusual
situations that have not caused by
the program.
Normally we cannot recover from
them.
So we don’t handle errors.

7. Using multiple catches &Trys
Catches must be in the same order as
exception hierarchy (sub class to super
class)
Largest catch must be the last.
Some exceptions cannot use without a
risk. eg:-IOException,InterruptedException
Multiple trys & trys inside try is possible.

8. Checked & Unchecked
Exceptions
Some Exceptions are checked in compile
time.
RuntimeExceptions and it’s subclasses
are unchecked.
Others are checked in compile time.
The keyword throws is used to guard
risky methods. It’s not handling &just
passing the bulk.

9. Re throwing Exceptions
We can re throw exceptions from the
catch clause.
Can give a try-catch from within a catch
clause.
Cannot use the same Exception name in
re throwing.

10. JVM & Programmatically thrown
Exceptions
JVM exceptions – either exclusively or
most logically thrown by JVM.
Eg:- nullpointer exception
Programmatic – thrown by application
and/or programmer.
Eg:- NumberformatException,
IllegalArgumentException