Self-Test 6

Wed, Dec. 1 2010

Exercise:

Today we will create a class called Calculator that can add, subtract, multiply, and divide, as well as keep track of the accumulated results of calculations.

Before you start:
Find a calculator on your system and run it. Do the following calculations:

5 + 4 =	9
6 + 2 =	8 (previous result (9) is lost)
10 + 7 =	17 (previous result (8) is lost)
+ 3 =	20 (3 added to previous result)
* 4 =	80 (previous result multiplied by 4)
/ 8 =	10 (previous result divided by 8)
3 + 5 =	8 (previous result lost)

Your Calculator class should include the following methods:

a method to get the result
a method to clear the result
2 methods for each operation (add, subtract, mult, div):

One that takes two double parameters and resets result
One that takes one double parameter and uses result as one of the operands

Write a demo program for light testing.
Write junit tests for more thorough testing.

Note that java can now handle division by 0 - you get Infinity insead of an error...