This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
i'm starting to complete java exercises i find online (starting from the basics).
the task is: Exercise SumAndAverage (Loop): Write a program called SumAndAverage to produce the sum of 1, 2, 3, ..., to an upperbound (e.g., 100). Also compute and display the average. The output shall look like:
but in my program, when i enter an upperlimit of say 10 which totals to 55. i expect the average to be 5.5. but my program returns 5.0.
Emanuel Mensa wrote:but in my program, when i enter an upperlimit of say 10 which totals to 55. i expect the average to be 5.5. but my program returns 5.0.
That's because number is an int, which can only hold integer values (not fractional values such as 5.5).
Lines 34 and 35 are wrong. Don't store the result in number. Remove those lines, just return number divided by upperBound there. Since upperBound is a double, the result will be a double and the calculation will be correct.
You're also doing things wrong with static. When a variable is static, it means that only one copy of it exists which is shared by all instances of a class (see Understanding Instance and Class Members).
You're first setting upperBound in line 46, then you're passing it to the constructor of SumAndAverage in line 47, where you're setting it again (line 17), as if it is an instance variable instead of a class variable. Then you're again passing it to the calc method (line 49). The calc method doesn't need to get upperBound as a parameter - it can access the member variable (line 5) directly.