Difference between revisions of "Cycling Speed"
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− | Now that we have our constants, let go ahead to declare the rest of the variables we will need based on the formula | + | Now that we have our constants, let go ahead to declare the rest of the variables we will need based on the formula. We will also include a string variable to store our user's input. |
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double mdev; //a double because it will contain decimal spaces because of the circumference | double mdev; //a double because it will contain decimal spaces because of the circumference | ||
double speed; | double speed; | ||
+ | String input; | ||
</pre> | </pre> | ||
Revision as of 09:12, 31 March 2011
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ProblemYou are an employer on the software team of Bikers Forever, a bicycle company. The software team uses Java and the knowledge of the Java SDK to write programs for Biker Forever. You are a great COMP 1010 student so you already have an idea of writing in Java, so in breathless anticipation, you await your next assignment from the head of the software team :) You arrive at your desk on Monday morning and open your email in-box (as usual) to see this message from the head:
Hi <insert name here>,
Program Description
Formula
Output
You have entered 75 RPM and 20 rear teeth. Meters of development: 4.948008429403924 Speed [km/hour]: 22.266037932317655 Programmed by Bicycle Forever Date: September 18, 2008 *** End of Processing *** Thanks!, <insert name here>, I am confident you will do a great job. |
Cycling Speed | |
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SolutionTo program our solution, we will go through 4 steps:
In addition, we will be sure to comment through out our code, and follow correct programming standards as stated in [1]
Identify and declare all variables and constantsBased on The Boss's email to you, and the description of the program and formula, we can easily identify all the variables and constants important to the solution.
Declaration of Constants
final int FRONT_TEETH = 45; We also know the constant for the diameter is 70cm every-time. However, the diameter is not used in the calculations. Rather, the circumference is used to calculate the meters of development.
final int double WHEEL_CIRCUMFERENCE = (70 * Math.PI)/100.0; Now that we have our constants, let go ahead to declare the rest of the variables we will need based on the formula. We will also include a string variable to store our user's input. int rpm; int rearTeeth; double mdev; //a double because it will contain decimal spaces because of the circumference double speed; String input; Store user input on bicycle informationThe code file contains more than one statements on each line. int digit1 = (isbn % 10);int total = digit1 * 9;isbn = isbn / 10; int digit2 = (isbn % 10);total = total + digit2 * 8;isbn = isbn / 10; Each of the above lines of code performs a similar function. Each line can be interpretted as a block of code. By placing each statements on a separate line and grouping the statements into appropriate code blocks, the result should look something like the following: int digit1 = (isbn % 10); int total = digit1 * 9; isbn = isbn / 10; int digit2 = (isbn % 10); total = total + digit2 * 8; isbn = isbn / 10; By placing each of the statements on a separate line, the readability of the code increases dramatically. Perform the calculationsOnce the statements are readable, the next step would be to organize them into code blocks as stated in COMP 1010 Coding Standards. Continuing with our previous example, the functionality of the code can be broken into two distinct code blocks. int digit1 = (isbn % 10); int total = digit1 * 9; isbn = isbn / 10; int digit2 = (isbn % 10); total = total + digit2 * 8; isbn = isbn / 10; Almost each line of code in the messy code file can be considered a separate code block. Take the time to read the code and understand how everything works together before deciding which statements should be grouped together. One of the code blocks that should be added is a variable declaration code block at the beginning of the main method. Throughout the messy code, integers are declared. All of the declaration statements should be placed at the beginning of the main method to ensure the code stays organized. Going to the previous example, two declaration statements can be moved to the top as depicted below. int digit1; int digit2; digit1 = (isbn % 10); int total = digit1 * 9; isbn = isbn / 10; digit2 = (isbn % 10); total = total + digit2 * 8; isbn = isbn / 10; Output the resultsAt the top of the main method, there should now be a number of variables declared. Notice that there are nine different "digit" variables which are only used once to store the same calculation. int digit1; int digit2; digit1 = (isbn % 10); int total = digit1 * 9; isbn = isbn / 10; digit2 = (isbn % 10); total = total + digit2 * 8; isbn = isbn / 10; The code sample from above shows two of the nine digit variables. These two variables can be replaced with a single one as follows: int digit; digit = (isbn % 10); int total = digit * 9; isbn = isbn / 10; digit = (isbn % 10); total = total + digit * 8; isbn = isbn / 10; Bonus Section: Outputting the Current DateThe messy code contained a total of eight different coding errors. Each error presented in this section is ordered as it appears in the code from the case study. Commenting and Testingint isbn = Temp; There are two problems with the above code sample. The first problem being that the variable "Temp" is of type string and not of the primitive type int. The second problem is the name of the variable "Temp". The variable was originally declared as "temp" and Java is a case sensitive language. Both programs are repaired by replacing the code with the line below. isbn = Integer.parseInt(temp); | ||
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