11.1 Exceptions
An Exception can be anything which interrupts the normal execution of the program. When an exception occurs program processing terminates abnormally. In such cases we get a system generated error message. The good thing about exceptions is that they can be handled.
An exception can occur for many different reasons like Opening a non-existing file, Network connection problem, invalid data entered, class file missing which was supposed to be loaded and so on.
Types of exceptions
Checked exceptions
A checked exception is an exception that occurs at the compile time, these are also called as compile time exceptions.
If these exceptions are not handled/declared in the program, it will give compilation error.
Examples of Checked Exceptions :-
ClassNotFoundException
IllegalAccessException
NoSuchFieldException
EOFException etc.
Unchecked Exceptions
Runtime Exceptions are also known as Unchecked Exceptions as the compiler do not check whether the programmer has handled them or not but it’s the duty of the programmer to handle these exceptions and provide a safe exit.
These exceptions need not be included in any method’s throws list because compiler does not check to see if a method handles or throws these exceptions.
Examples of Unchecked Exceptions:-
ArithmeticException
ArrayIndexOutOfBoundsException
NullPointerException
NegativeArraySizeException etc.
Advantages of Exception Handling
1. Exception handling allows us to control the normal flow of the program by using exception handling in program.
2. It throws an exception whenever a calling method encounters an error providing that the calling method takes care of that error.
3. It also gives us the scope of organizing and differentiating between different error types using a separate block of codes. This is done with the help of try-catch blocks.
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