(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.