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COSC 1331 Lab 2: Counting Coins and Making Change The Coins Class Objectives • Use methods. • Use local variables. • Use arithmetic expressions. • Use Scanner to input values. • Use a class constant.

COSC 1331

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Lab 2:

Counting Coins and Making Change

The

Coins

Class

Objectives

Use methods.

Use local variables.

Use arithmetic expressions.

Use Scanner to input values.

Use a class constant.

Hand-in Requirements

All projects and laboratories will be submitted electronically through Canvas.

Zip up

your entire lab directory to submit as the source.

(Right click on the lab folder and

follow

Send To > Compressed (zipped) Folder

or

7-Zip > Add to “lab2.zip”

).

The lab

folder should include the following:

Coins.java

CoinsOutput.txt

Tasks

Write a program that prints

Lab 2 written by YOURNAME

and calls two methods:

1.

Input the number of quarters, dimes, nickels, and pennies from the user.

Print

out the number of coins and total value in dollars.

2.

Input the number of cents from the user.

Determine and print out the number of

quarters, dimes, nickels, and pennies to add up to that number of cents.

No, you

can’t use all pennies.

Details

Getting Input from the User

You can get input from the user using a Scanner object.

Here is an example program

with key lines in bold.

import java.util.*;

public class HalfDollar {

public static final Scanner CONSOLE = new Scanner(System.in);

public static void main(String[] args) {

halfDollarAmount( );

}

public static void halfDollarAmount( ) {

System.out.print(“Enter the number of half dollars: “);

int halfDollar = CONSOLE.nextInt( );

double amount = halfDollar * 0.50;

System.out.println(halfDollar + ” half dollars is $” + amount);

}

}

The import statement tells Java that we want to use Java’s

java.util

package (Scanner is

part of this package).

The statement:

public static final Scanner CONSOLE = new Scanner(System.in);

declares a special kind of variable (a

class constant

) named

CONSOLE

of

type

Scanner

and stores an “object” for input from the keyboard

in

CONSOLE

.

CONSOLE

can be used anywhere in the class.

The first two statements of the

halfDollarAmount

method:

1.

prompt the user for information, and

2.

input a number from the keyboard and stores the number in a variable

named

halfDollar

.

You only need the declaration/assignment for

CONSOLE

once in the class.

On the other

hand, you need prompt and input statements for each value you want the user to enter.

Local Variables

You should have local variables for each value that is entered and each value that you

calculate.

For example, for the first method there should be a local variable that stores

the total dollar amount of the change, as well as a local variable for the total number of

coins.

Making Change

For the second method, we can use integer division and the mod operator to make

change.

Suppose the user enters 99 as the number of cents.

The sequence of

calculations should be as follows.

1.

The integer division

99

/

25

can be used to determine the number of quarters (3).

2.

Using the mod operator

99

%

25

determines the remaining number of cents to be

converted into change (24).

3.

Integer division

24

/

10

can be used again to determine the number of dimes (2).

4.

The mod operator

24

%

10

can be used again to determine the remaining amount

(4).

5.

Next, for nickels, integer division

4

/

5

for the number of nickels (0) and a mod

operation

4

%

5

for the remaining amount (4).

6.

Whatever is left is the number of pennies (4).

Of course the values that were calculated (3, 24, 2, 4, 0, 4) would be different if the user

enters something different from 99.

This means we should have variables to store all of

these values.

For example, we might have a variable named

cents

to hold the value that

the user entered, a variable named

remainingAfterQuarters

for the remaining amount

after the quarters are determined, which could be assigned by:

int remainingAfterQuarters = cents % 25;

Output File

Include the output of your program in a file named

CoinsOutput.txt

.

Rubric

Your program should compile without any errors.

A program with more than one or two

compile errors will likely get a zero for the whole assignment.

The following criteria will also be used to determine the grade for this assignment:

[Points] If the main method of your program prints “Lab 2 written by […]”.

[Points] If your submission was a Zip file named

lab2.zip

containing a folder

named

lab2

, which contains the other files.

[Points] If your Java program was in a file named

Coins.java

.

[Points] If the output of your Java program was in a file named

CoinsOutput.txt

.

[Points] If your program contains a comment that describes what the program