CSC 1016S Assignment 2: Introduction to objects and classes solved

Description

Assignment Instructions
This assignment involves constructing programs in Java using class declarations to model simple
types of object.
Exercise One [25 marks]
Write a Student class to model a student’s name, composed of a first name, middle name and last
name. The class should meet the following specification:
Class Student
A Student object represents a student. A student has a first name, middle name and last name.
Instance variables
private String firstName;
private String middleName;
private String lastName;
Methods
public void setNames(String first, String middle, String last)
// Set the first, middle and last names of this Student object.
public String getFullName()
// Obtain the full name of this Student with the middle name converted to an initial only.
Write a driver class called ‘TestStudent’ containing a main method. The main method should
1. Ask the user to input a student’s first, middle and last names,
2. Create an instance of the Student class.
3. Call setNames using the data input by the user.
4. Call the method to compute the full name and output it.
Sample I/O
Enter first name:
Tito
Enter middle name:
GimmeYourMoney
Enter last name:
Mboweni
The full name is: Tito G. Mboweni
Exercise Two [25 marks]
This question concerns developing a pseudo random number generator (PRNG). Java provides a
perfectly serviceable PRNG (java.util.Random), however, building one is a useful OO exercise
and offers an insight into these things are done.
A pseudo random number generator is a device that can produce or output a sequence of numbers
that appear to be randomly selected.
One approach to developing a PRNG is based on the following general formula:
CONTINUED
𝑋𝑘+1 = (𝑔𝑋𝑘 + 𝑐) 𝑚𝑜𝑑 𝑛
(Note that the word “mod” denotes the modulo operation. For example, 5 mod 3 is 2.)
The formula describes a sequence of pseudo random values. The term 𝑋𝑘 denotes one value in the
sequence while 𝑋𝑘+1 denotes the next. Given a value in the sequence, we calculate the next by
applying the formula. Customarily, a seed or start value, 𝑋0 is provided with which to kick the whole
thing off.
According to this Wikipedia page, good values for the constants are:
𝑐 = 0
𝑔 = 48,271
𝑛 = 2
31 − 1 = 2,147,483,647
Here’s a specification for a RandomNumber generator class:
Class RandomGenerator
A RandomGenerator is a Pseudo Random Number Generator (PRNG). Its implementation is
the Lehmer variant of linear congruential generator.
Instance variables
private long x;
// This field holds the most recently calculated value i.e. Xk.
Constructors
public RandomGenerator(long seed)
// Create a RandomGenerator object that uses the given seed as the value for X0.
Methods
public int nextInt()
// Return a pseudorandom integer value.
public int nextInt(int i)
// Return a pseudorandom integer value between 0 (inclusive) and the specified
value (exclusive).
public double nextDouble()
// Return a pseudorandom real number value between 0.0 (inclusive) and 1.0
(exclusive).
Construct a RandomGenerator class of object that meets the given specification and is
implemented using the given formula and constants.
 Note the use of the data type long for the instance variable x. The numbers that the
formula generates are very large integers hence this is the best choice.
 Each ‘next…’ method should obtain a value for 𝑋𝑘+1 and then use it to obtain the required
result.
o The nextInt() method should obtain the result of casting 𝑋𝑘+1 as an integer.
o The nextDouble() method should obtain the result of dividing 𝑋𝑘+1by 𝑛.
(You may wish to investigate the difference between, say, 3⁄4 and 3⁄4 . 0.)
CONTINUED
o The nextInt(int i) method should obtain nextDouble(), scale it and cast
it.
On the Vula page for this assignment you will find a test harness class called TestPRNG that may be
used to check your work. Here is an example of expected output:
Enter a seed value
7
Enter a parameter value for nextInt(int i):
10
Enter the number of calls required of each method.
5
nextInt(): 337897
nextDouble(): 0.5952271440044172
nextInt(10): 2
nextInt(): 518142577
nextDouble(): 0.7756899137868033
nextInt(10): 3
nextInt(): 1298864186
nextDouble(): 0.786058717307662
nextInt(10): 8
nextInt(): 439347582
nextDouble(): 0.6268343877172258
nextInt(10): 9
nextInt(): 162366641
nextDouble(): 0.6669665727144883
nextInt(10): 1
Note: you can comment out lines in the test harness, enabling incremental development of
RandomGenerator methods.
Also Note: The automaker will test methods individually, meaning that you can obtain partial marks
for an incomplete solution.
CONTINUED
Exercise Three [25 marks]
Consider the following specification for a Collator type of object:
Class Collator
A Collator object manages information on a sequence of readings. It records the number of readings, the
maximum, the minimum and the average.
Constructors
Collator()
Create a Collator object. The number of readings is set to zero.
Methods
void recordReading(int reading)
// Use the given reading to update the record.
int maximum()
// Obtain the largest reading taken. Requires numberOfReadings()>0.
int minimum()
// Obtain the lowest reading taken. Requires numberOfReadings()>0.
int average()
// Obtain the average of readings taken, rounded to the nearest integer. Requires
numberOfReadings()>0.
int numberOfReadings()
// Obtain the number of readings which have been taken. Requires numberOfReadings()>0.
NOTE:
 Individual readings do not need to be stored.
Only average, number of readings, maximum and minimum are required.
 Average must be stored as a real number even though it is reported as an integer.
Hint: use (int)Math.round(average) to obtain the reported value.
Construct a class declaration for Collator, and then build a program called Meteorology that
uses 3 Collator objects, one for temperature, one for pressure, one for humidity, and that
behaves as follows:
Meteorology Program
Make a selection and press return:
1. Record a temperature reading.
2. Record a pressure reading.
3. Record a humidity reading.
4. Print maximum values.
5. Print minimum values.
6. Print average values.
7. Quit
1
Enter value:
17
Make a selection and press return:
1. Record a temperature reading.
2. Record a pressure reading.
CONTINUED
3. Record a humidity reading.
4. Print maximum values.
5. Print minimum values.
6. Print average values.
7. Quit 4
Maximum temperature: 17
Maximum pressure:
–
Maximum humidity:
–
Make a selection and press return:
1. Record a temperature reading.
2. Record a pressure reading.
3. Record a humidity reading.
4. Print maximum values.
5. Print minimum values.
6. Print average values.
7. Quit 2
Enter value:
1020
Make a selection and press return:
1. Record a temperature reading.
2. Record a pressure reading.
3. Record a humidity reading.
4. Print maximum values.
5. Print minimum values.
6. Print average values.
7. Quit 1
Enter value:
11
Make a selection and press return:
1. Record a temperature reading.
2. Record a pressure reading.
3. Record a humidity reading.
4. Print maximum values.
5. Print minimum values.
6. Print average values.
7. Quit 5
Minimum temperature: 11
Minimum pressure: 1020
Minimum humidity:
–
Make a selection and press return:
1. Record a temperature reading.
2. Record a pressure reading.
3. Record a humidity reading.
4. Print maximum values.
5. Print minimum values.
6. Print average values.
7. Quit 3
Enter value:
87
Make a selection and press return:
1. Record a temperature reading.
2. Record a pressure reading.
CONTINUED
3. Record a humidity reading.
4. Print maximum values.
5. Print minimum values.
6. Print average values.
7. Quit
6
Average temperature: 14
Average pressure: 1020
Average humidity: 87
Make a selection and press return:
1. Record a temperature reading.
2. Record a pressure reading.
3. Record a humidity reading.
4. Print maximum values.
5. Print minimum values.
6. Print average values.
7. Quit
7
Exercise Four [25 marks]
The Acme cash register is a simple device that is used in commerce to calculate sales and change
due. (Actually, strictly speaking, it’s not a register at all since it does not record sales. It just assists
with the calculations.)
The device supports customer transactions in the following way:
 Ready to ring up a customer’s purchases, the running total is initially zero.
 As the operative enters the price of each item the running total is updated.
 Once the final item has been added, requesting payment, the operator may enter the
amount tendered. This causes the cash drawer to open along with the calculation of the
change that is due.
 Having received payment and obtained change as required, closing the cash drawer serves
to complete the transaction, setting the running total, amount tendered and change due
back to zero.
 The running total may be examined at any point.
 A transaction can be cancelled at any point. All values stored by the register revert to zero.
An Acme cash register simulator is required. Here is sample I/O for the program:
Cash Register
Running total: R0.00
1. Ring up item.
2. Enter amount tendered.
3. New transaction.
4. Quit
1
Enter amount:
34.50
Running total: R34.50
1. Ring up item.
2. Enter amount tendered.
3. New transaction.
4. Quit
2
CONTINUED
Enter amount:
50
Running total: R34.50
Amount tendered: R50.00
Change due: R15.50
1. Ring up item.
2. Enter amount tendered.
3. New transaction.
4. Quit
3
Running total: R0.00
1. Ring up item.
2. Enter amount tendered.
3. New transaction.
4. Quit
4
Design and implement a CashRegister class that models Acme cash register function, and then
write a program called RegisterUI that uses a CashRegister object, providing I/O.
Use the design of the meterology program of question 3 to guide you:
 The CashRegister class should contain methods for each register function.
 The RegisterUI class should be responsible for creating a CashRegister object,
obtaining user input, calling the CashRegister object’s methods, and printing results.
 The CashRegister class should NOT contain any print statements.
Note that five of the marks available for this question will be for good design practices – meaningful
names, adequate quantity of methods, adequate choice of data types etc. To obtain these marks you
must present your work to a tutor.
Marking and Submission
Submit the Student.java, TestStudent.java, RandomGenerator.java, Collator.java, Meteorology.java,
CashRegister.java and RegisterUI.java files contained within a single .ZIP folder to the automatic
marker. The zipped folder should have the following naming convention:
yourstudentnumber.zip
END