Advantage
of Exception/Error Handling:
·
Error-handling codes are separated from
the normal program flow to increase the readability and maintainability.
·
This location of the exception/error is
known exactly as entire stack trace is available to the user. This is very
helpful in debugging.
·
Programmer gets a chance to recover from
the error/abnormal condition.
·
With java, it is not must to test if an
exception/error condition happens. Adding more error/exception simply requires
adding more catch clauses, but the original program flow need not be touched.
When Exception/Error can occur?
There
are many cases where abnormal condition occurs during program execution, such
as:
·
The class file you want to load may be
missing or in the wrong format.
·
Integer division by zero
·
Array index is not the valid range (i.e.
from 0 to length -1)
·
The file you are trying to open may not
exits.
·
The file string, which you want to
convert to a number, is having invalid characters so that it cannot be
converted to a number.
·
You want to create an object but no more
memory is available
In java for each and every exception there is a
class.
The super class of all exceptions is Throwable.
Exception cl ass contains
details of the exception which occurs under the normal circumstances.
Error class contains those exceptions which do not
occur under the normal circumstances e.g. stack overflow. These exception are
not handled under normal situation
Pre-Defined
Classes of the Exception class:
Class Description
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1.
ArithmeticException This
class exception occurs when we divide the number by zero.
2.
ArrayIndexOutofBoundsException This class exception occurs
when we refer to an index outside the bounds or its size (0 to size-1).
3.ClassNotFoundException This
class exception occurs when we either create an object or reference of class ,
which we have not defined or which neither occurs in any package.
4.
StringIndexOutofBoundsException This
class exception occurs when we refer to an index outside the bounds in case of a string.
5.
NegativeArraySizeException This
class exception occurs when we specify a negative value as an array size
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