(i) Create three
Exception
classes (using extends Exception) that
correspond respectively to the following error situations:
• the first of the operands in the preceding exercise being non-numeric;
• the second being non-numeric;
• both being non-numeric. Give these classes empty constructor bodies, define the
toString
method for
each to return a meaningful error message and place the classes in a package
called
errorExceptions. Create a subdirectory of
classes
called
errorExceptions
and save these
Exception
classes (at least the
.class
files) into this directory.
(ii) Modify the JSP of the preceding exercise so that it imports package
errorExceptions
and throws an object of one of the three
Exception
classes just
defined, according to whether the first operand, the second operand or both
is/are non-numeric. (This involves some interesting logic that includes nested
try blocks.) If you are going to change the name of your error page (which
will require modification, as noted below), remember to change its name in this
JSP's page directive.
(iii) Modify the associated JSP error page so that it makes use of the
toString
method of the implicit
exception
object (if it didn't already do so) and allows
return to the correct JSP.
.