Homework Assignments - Spring 2010

Intro to Object-oriented Programming with Java (COP 2551)

Assignments, due dates, and hints are given below, most recent first. Homework is due by midnight of the date shown. Send your homework as an email attachment from your FCCJ email account to sdifranc@fscj.edu. Include your name, homework number, and the class and reference number in the subject line as described in the homework guidelines.

Note: If you are asking for help on an assignment, rather than turning it in, make sure to include the word "Help" in the subject line.

Hw07: ArrayLists of objects (due 3/11)

For this assignment you will write a program to maintain a simple portfolio of stocks. First, write a public class Stock with these features:

• private instance variables coName (the name of the company), sharesHeld (the number of shares of that company owned), and sharePrice (the current price of one share of stock).
• A two-argument constructor that sets coName and sharesHeld to the arguments specified, and the sharePrice to 0.00. Validate the argument for sharesHeld to ensure it is non-negative; set it to 0 if it is.
• Three accessor methods, each of which returns the value of one of the instance variables (getCoName, getSharesHeld, getSharePrice).
• One mutator method setSharePrice that sets the current price per share (PPS). Validate the argument to be non-negative; set it to 0.00 if it is.

Include in your class a main method that helps test the class in these ways:

• Declares an ArrayList of Stock objects that represents a stock portfolio.
• Instantiates three Stock objects and adds them to the ArrayList. (For example, "Xerox" with 100 shares, "Dow Chemical" with 150 shares, and "General Motors" with 1050.)
• Prompts the user to provide today's PPS for each stock, extracting the name of the company for the prompt by traversing the ArrayList, and using the setSharePrice method to set the instance variable.
• Produces a nicely formatted report of current portfolio value like the one in this sample executable: Stock.class

Remember: Start with a minimal main method. Get your class working before you try to include all the functionality described above.

Submit your program as Stock.java

Hw06: Array statistics (due 3/4)

Write a program to compute and display some statistics for the grades in this array:

int [] grades = {98, 87, 78, 100, 99, 67, 69, 50,                  88, 100, 88, 79, 60, 75, 93, 97,                  40, 98, 88, 62, 58, 85, 92, 93,                  59, 98, 94, 95, 87, 47, 69, 79,                  89, 85, 68, 75};

You should compute these statistics in separate methods (except for number of grades), and return the value for display in main: number of grades, maximum grade, minimum grade, mean (average) grade, and:

• The average (mean) grade (x). This is calculated simply as the sum of the grades divided by the number of grades in the array.
• The standard deviation. To compute the standard deviation s, use this formula:

Where x_i is each individual grade, x is the mean of the grades, and n is the number of grades.

• "Unusual scores". Determine which of the grades, if any, are "unusual" in the sense that their corresponding z-score is < -2.0 or > +2.0. A z-score is computed as:

Here is a sample executable, using the above data: ArrayStats.class

This is a team assignment. Please review the guidelines for team assignments. Here are the teams:

• Nathan B (belang) & Vishni M (mahavi)
• Kerri B (boydka) & John C (caoij)
• Seta C (setac) & Kenny F (feieka1)
• Cassandra C (spracm) & Lee M (lem27)
• Garry D (dimagf) & Brad G (gonzbd1)
• Eddy H (hensea) & Mehrdad J (jamsm)
• Ellis H (hollel) & Misagh K (kerim2)
• David R (reevda2) & Robert W (walkrd2)
• Jason V (voorjb) & Jason T (truejr)

Submit your program as ArrayStats.java. Whoever is designated to submit the program, please make sure the cc your teammate so they will know it has been submitted.

Hw05: Writing a class (due 2/25)

Write a class named CorporateName that has one instance variable representing the name of a corporation. Objects of the class will have one instance variable (a String) representing the name (e.g., "International Business Machines"). The class should have methods to:

1. Instantiate a new object with the corporate name specified as an argument (a String)
2. A setName method that allows the name to be changed to a new name
3. A getName method that returns a String representing the corporate name
4. A toString method that returns a String representing the corporate name in quotations (i.e., "International Business Machines")
5. A shortName method that returns an uppercase String of of the first letters of each of the words in the corporate name (i.e., "IBM")
6. A domainName method that returns a lower case String in the format www.shortName.com

Use this main method to test your class. Remember not to write the whole class at one time; comment out the lines in main that you do not want to test yet.

public static void main( String [] args ) {    CorporateName cn1 =       new CorporateName("International Business Machines");    CorporateName cn2 =       new CorporateName("American Micro Devices");    System.out.println("Corporate name #1 is "       + cn1.getName());    System.out.println("Corporate name #2 is "       + cn2);  /* will invoke toString */    System.out.println("Short name for Corporate name #2 is "       + cn2.shortName());    System.out.println("A suggested domain name is "       + cn2.domainName());    cn2.setName("Cubic Conundrum Corporation");    System.out.println("Revised corporate name #2 is "       + cn2 ); }

Here is a sample executable: CorporateName.class

Save and submit your program as CorporateName.java.

Hw04: Iteration (due 2/11)

Write a program that will display a two-dimensional table of the annual cost of gasoline, where the columns represent different prices per gallon of gasoline and the rows different miles per gallon of auto efficiency. Here is an example executable : MPG.class that produces this output:

Use the principles of encapsulation and generalization design your program with efficient functions. The formula for annual cost is:

annualCost  = (18000 / mpg) * pricePerGallon

You can round the annual cost to the nearest dollar and insert a comma if needed by using the printf method and the conversion specifier ",8.0" where 8 is the field width.

As an added challenge, you can ask the user to input the annual miles driven (and use this value in the calculation above (rather than 18,000).

Save and submit your program as Hw04_xxx.java, where xxx are your initials.

Hw03: Selection Structures (due 2/4)

Obesity is a growing health problem in the United States, greatly increasing the risk of developing conditions such as high blood pressure, diabetes (type 2), heart disease, stroke, gallbladder disease and cancer of the breast, prostate and colon. The American Obesity Association reports that:

The number of adults in the United States who are overweight or obese has continued to increase, as shown in the table below. Currently, 64.5 percent of U.S. adults, age 20 years and older, are overweight and 30.5 percent are obese. Severe obesity prevalence is now 4.7 percent, up from 2.9 percent reported in the 1988 - 1994 National Health and Nutrition Examination Survey (NHANES) by the Centers for Disease Control and Prevention (CDC).

BMI is calculated with this formula, using a fruitful method:

BMI = ( weight (lbs) / height (inches)² ) x 704.5

Note that in the English system of measurement, there are 12 inches in one foot. For example, a 195-pound man 5 feet and 10 inches tall ( = 12 x 5 + 10 = 70 inches) would have a BMI of:

( 195 / (70)² ) x 704.5 = ( 195 /  4900 ) x 704.5 = 28.0

Write a program that computes BMI for a person, given as input the person's weight in pounds and height in inches. You should provide appropriate prompts for the input required. Your program should output the calculated BMI, and the phrase "You are ..." followed by: "Overweight", "Obese", or "Severely Obese" if the BMI is in the ranges defined in the table above, "Underweight" if BMI is < 20, and "Normal" if BMI is in the range 20 <= BMI < 25.

For an extra (optional) challenge: If the person has a BMI of 25 or more, also compute how many pounds the person should lose to attain a BMI of 24, and output the message: "You should try to lose at least x pounds" (where x is the number of pounds calculated). If the person has a BMI of less than 20, compute how many pounds the person should gain to attain a BMI of 20, and output the message: "You should try to gain at least x pounds" (where x is the number of pounds calculated). If a person has a BMI in the "Normal" range, output the message: "You are maintaining a healthy weight."

Here is a compiled class from the sample solution you can run to see the interface and to check your work: Bmi.class

Save your class and submit your program as Hw03_xxx.java, where xxx are your initials.

Hw02: Writing and using methods (due 1/28)

Write a program to calculate the future value of an investment paying compound interest, based on user inputs for principal (p) deposited (the amount of the investment), the annual interest rate (r) paid (in percent), and term (t) of the investment (in months). Assume that interest is paid monthly. The formula for computing future value (fv) is:

     fv = p(1 + (r / 100))^t

Note that r and t need to be in the same time units: if t is given in months, then r should be the monthly interest rate. You can convert annual interest rate to monthly interest rate by dividing it by 12.0.

Write your class (program) with three methods:

1. A main method that obtains user inputs and displays the results
2. A splash method that displays a splash screen describing what the program does
3. A calcFV method that calculates and returns the future value, given three values as arguments by the calling method: principal, interest rate, and term.

Here is a compiled program you can use to observe the interface and to test your program: Compound_Interest.class. Note that this is a compiled file and cannot be opened in an editor or IDE. You can run it, however, with the JRE. Use this procedure:

1. Right-click on the file, and from the context menu download it to the folder of your choice on your hard drive or thumb drive. (In the screen session below it has been saved to C:\temp)
2. Start a command window (Start -> Run -> command)
3. Change to the drive and folder where you saved the file
4. Run the file: java Compound_Interest

Here is a sample command window that starts the program:

Save your class and submit your program as Hw02_xxx.java, where xxx are your initials.

Hw01: Using The JCreator IDE (due 1/21)

Modify the program given in the JCreator IDE Tutorial to prompt the user for a number of students who have signed up for the senior class trip to Washington, D.C., then calculate the number of full buses (each can hold 42 students) needed, and the number of students that will be on the last partially-filled bus (i.e., the number of students "left over"), if any, and display the result.

Save your source code with the filename Hw01_xxx.java, where xxx are your initials, and email to me as an attachment from your student email account as described in the homework guidelines. Note: This means the name of your class must be Hw01_xxx:

   public class Hw01_xxx
   { ...