ASSIGNMENT
Part 1: Warm-up
Do NOT submit this part, as it will not be graded. However, doing these exercises might help you to do the second part of the assignment, which will be graded. If you have difficulties with the questions of Part 1, then we suggest that you consult the TAs during their office hours; they can help you and work with you through the warm-up questions. You are responsible for knowing all of the material in these questions.
Warm-up Question 1
Create a file called HelloWorld.java, and in this file, declare a class called HelloWorld. This class should define only one method called main(). In the body of this method, use System.out.println() to display "Hello world!". You can find such a class in the lecture slides; make sure you can compile and run it properly.
Warm-up Question 2
Create a file called Diagram.java, and in this file, declare a class called Diagram. This class should define only one method called main(). In the body of this method, use five statements of System.out.println() to display the following pattern:
Use Strings composed out of the space character and the character ‘2'. For a bit of fun, try to draw the pattern ‘202'.
Warm-up Question 3
Practice with Binary:
We usually use base 10 in our daily lives, because we have ten fingers. When operating in base 10, numbers have a ones column, a tens column, a hundreds column, etc. These are all the powers of 10.
There is nothing special about 10 though. This can in fact be done with any number. In base 2, we have each column representing (from right to left) 1,2,4,8,16, etc. In base 3, it would be 1,3,9,27, etc.
Answer the following short questions about number representation and counting.
1. In base 10, what is the largest digit that you can put in each column? What about base 2? Base 3? Base n?
2. Represent the number thirteen in base 5.
3. Represent the number thirteen in base 2.
4. What binary number is equal to the sum of these two binary numbers? 10101011 + 10010001
5. What is the number from part 4, in base 10?
6. What is the binary number for 11010010 + 11000101? Note: Don't worry about overflow here
7. And what is the number from part 6, in base 10?
Warm-up Question 4
1. What does the following logical expression evaluate to? (false or false) and (true and (not false))
2. Let a and b be boolean variables. Is it possible to set values for a and b to have the following expression evaluate as false?
b or (((not a) or (not a)) or (a or (not b)))
Part 2
The questions in this part of the assignment will be graded.
Question 1: Calculator Program
Assignment is a file called Calculator.java. Note that there is a marked section where your code must go. The code outside of this area must not be modified. Your name and student number must be written at the top of the file.
Let a, b, and c be the three numbers the program receives as input arguments...
Write Java code in the marked area to print the following calculations:
1. The sum of a and b.
2. The product of a and b.
3. The result of dividing a by b.
4. The result of dividing a by c.
5. A statement saying whether a is larger than b.
6. A statement saying whether a an odd number. Use the mod operator %.
For example, if the program is run with input arguments 5, 5, and 1, the output should be:
The first argument a is: 5
The second argument b is: 5
The third argument c is: 1.0
Sum of a and b: 10 Product of a and b: 25 Dividing a by b: 1 Dividing a by c: 5.0
Is a larger than b: false
Is a odd: true
Be sure to include the specified text on each output line. That is, concatenate a String literal with the value of a variable.
For the division results in this question, don't worry about handling division by zero.
Input Arguments Note that this program is run by providing input arguments. That is, a, b, and c do not have a fixed value. Their values will depend on the input provided when running the program.
Question 2: Creating a Lemonade Stand Sales Program
The goal of this question is to write several methods to create a program for doing calculations for a lemonade stand. All the code for this question must be placed in a file named LemonadeStand.java. Note that this means the class must also be named LemonadeStand.
You have to write methods that perform the following tasks:
• Printing total sales
• Performing ‘safe' division
• Determining the maximum of two numbers
• Calculating various statistics of the lemonade stand
Hint: To test these methods, create a main method. The main method will not be graded in LemonadeStand.java, but without it, you won't know whether or not your methods work! Your main method should call the below methods a few times using different input data so that you can verify the methods are working correctly. You should think of a few cases to test!
2a) Void Method for Printing Total Sales
Write a method printTotalSales that takes as input one integer parameter and one double parameter. The first parameter is an integer called numSales, while the second parameter is a double storing the price for each sale.
You must print these two numbers, as well as the result of multiplying them together. For example, if the method is called with the parameters 17 and 4.45, then the message printed must be: We sold 17 units at $4.45 each, which totals $75.65.
Note that for full marks, this message must be written on one line. Research the + operator for Strings, or the System.out.print() and System.out.println() statements.
2b) Method for Division
Write a method divide inside of LemonadeStand.java that takes two integer parameters. This method should return the result of dividing the first parameter by the second'. The parameters names don't matter, but should be logical, such as a and b or first and second. The return value must be an integer value.
Note that division doesn't work properly if the second parameter is zero. Therefore, if the second parameter is zero, the method should print an appropriate error message before the division occurs, and then return zero. Note: this means that the program must not crash. Your method must not print anything if the second parameter is not zero.
To test your divide method, you will need to call it from your main method. Think about how you can call the method and then display the answer. Make sure to test the cases where the second parameter is 0, and where it is not 0.
2c) Maximum Method
Write another method getMaximum that takes two integer values as input, and returns an integer which is the larger value of the two parameters. In the case of a tie, return the value of either variable. Don't use the built-in max method.
2d) Statistics Method
Now use the printTotalSales, divide, and getMaximum methods to calculate some statistics for the lemonade stand.
Write a method standStats that takes as input two integer parameters and one double parameter. The return value must be void.
• The first parameter numDays corresponds to the number of days the stand was open.
• The second parameter numSales corresponds to the number of units sold.
• And the third parameter price corresponds to the price per unit.
First, call the printTotalSales method with numSales and price as parameters.
Second, create a variable salesPerDay to store the number of sales per day. This integer variable must store the result of calling the division method with the numSales and numDays parameters. Note that this will be integer division, without a decimal value.
Third, print the value of salesPerDay in a message. For example, the message could be With 41 sales over 7 days, the sales per day were 5.
Fourth, create an integer variable targetSales. Assign this variable the value obtained by calling the getMaximum method with the salesPerDay variable and the value 10. This will set the target sales to be the larger of the sales per day or 10 sales.
Fifth, print a message detailing the target sales for the lemonade stand. For example, the message could be The target sales are now: 10.