Exceptions are events that disrupt normal program flow, such as invalid user input or file access errors. Errors are problems beyond the programmer's control. Exceptions can be checked, which must be caught, or runtime, which can be ignored. The try block contains exception-prone code, catch handles specific exception types, and finally ensures cleanup. Common exceptions include NullPointerException and ArrayIndexOutOfBoundsException. Exception handling separates error handling from regular code and groups error types for easier management.

1. Exception Handling

2. What is exception ?
● An exception is an event that occurs during the
execution of a program that disrupts the
normal flow of instructions.
● Anything that occurs in an unexpected way is
called as exception

3. Error
● These are not exceptions at all, but problems
that arise beyond the control of the user or the
programmer.
● Errors are typically ignored in your code
because you can rarely do anything about an
error.

4. Difference between Error and
Exception
● An Error "indicates serious problems that a
reasonable application should not try to catch.”
● An Exception "indicates conditions that a
reasonable application might want to catch."

5. Why exception occurs
An exception can occur for many different
reasons, including the following:
● A user has entered invalid data.
● A file that needs to be opened cannot be
found.
● A network connection has been lost in the
middle of communications or the JVM has run
out of memory.
●

6. Types of Exceptions
● Checked exceptions
● Runtime exceptions

7. Checked Exception
● A checked exception is an exception that is
typically a user error or a problem that cannot
be foreseen by the programmer.
● For example, if a file is to be opened, but the
file cannot be found, an exception occurs.
These exceptions cannot simply be ignored at
the time of compilation.

8. Runtime Exception
● A runtime exception is an exception that
occurs that probably could have been avoided
by the programmer.
● As opposed to checked exceptions, runtime
exceptions are ignored at the time of
compilation.

9. Categories of exception
●
In Java, it is possible to define two catergories of Exceptions and Errors.
● JVM Exceptions: - These are exceptions/errors that are exclusively or
logically thrown by the JVM.
●
Examples : NullPointerException, ArrayIndexOutOfBoundsException,
ClassCastException,
● Programmatic exceptions: - These exceptions are thrown explicitly by
the application or the API programmers
●
Examples: IllegalArgumentException, IllegalStateException.

10. Advantages of exception handling
● Separating Error-Handling Code from
"Regular" Code
● Grouping and Differentiating Error Types

11. Keywords to handle exceptions
Exception Handling contains 5 keywords
● 1. try
● 2. catch
● 3. finally
● 4. throws
● 5. throw

12. Syntax for Exception handling
try
{}
catch(Exception e){
}
Finally{
}

13. Purpose of try, catch and finally
● The try block identifies a block of code in which an
exception can occur.
● The catch block identifies a block of code, known as an
exception handler, that can handle a particular type of
exception.
● The finally block identifies a block of code that is
guaranteed to execute, and is the right place to close
files, recover resources, and otherwise clean up after the
code enclosed in the try block.
●

14. Exception Hierarchy

15. Example of Exception handling

16. Sample output