CHECKED EXCEPTION IS TO BE HANDLED BY USE TRY AND CATCH
EXCEPTION....THAT HAS TO BE THROWN AND CATCH USEING THIS
EXCEPTION...WERE AS UNCHECKED EXCEPTION IS RUN TIME EXCEPTION.  
THIS EXCEPTION IS NOT CHECKED AT THE TIME OF COMPILATION
HENCE IT CANNOT BE HANDLED WITH TRY AND CATCH.....

A checked exception is one, which a block of code is likely
to throw, and represented by throws clause.It represents
invalid conditions in areas outside the immediate control of
the program (invalid user input, database problems, network
outages, absent files).
In Java it is expected that a method 'throws' an exception
which is a checked exception.They are subclasses of Exception.
While unchecked exceptions represent defects in the program
(often invalid arguments passed to a non-private method).
According to definition in The Java Programming Language, by
Gosling, Arnold, and Holmes,"Unchecked runtime exceptions
represent conditions that, generally speaking, reflect
errors in your program's logic and cannot be reasonably
recovered from at run time." They are subclasses of
RuntimeException, and are usually implemented using
IllegalArgumentException, NullPointerException, or
IllegalStateException
It is somewhat confusing, but note as well that
RuntimeException (unchecked) is itself a subclass of
Exception (checked)