VENDING MACHINE CHANGE CALULATOR

This is a sample app for a change calculator in a vending machine. The intent is that based on the total of a purchase and the coins used to pay, calculate what coins should be used to pay for the purchase.

Prerequisite

Required:

• java

Suggested:

• mvn

Optional

• docker

Installation

This is a multi-module maven project. To build the modules for this project

On systems with mvn installed

mvn install

On Windows without mvn installed

.\mvnw.cmd install

On Linux without mvn installed

./mvnw install

Useage

To use the library in another application

Add the dependancy to your project:

Maven

    <dependency>
      <groupId>oracle.exercise</groupId>
      <artifactId>api</artifactId>
      <version>0.0.1-SNAPSHOT</version>
    </dependency>

Gradle

oracle.exercise:api:0.0.1-SNAPSHOT

Starting the application

To use the test harness you can run the following

Windows example command

java -jar .\harness\target\harness-0.0.1-SNAPSHOT-jar-with-dependencies.jar

Linux example command

java -jar ./harness/target/harness-0.0.1-SNAPSHOT-jar-with-dependencies.jar

Using Docker

To run this application using docker, build the application with the above command, then run the container using docker.

docker run -it vending-machine-harness:0.0.1-SNAPSHOT

Using the test harness

Setup

The application will prompt you to enter values for the float for a vending machine.

Each of the coins registered in the CoinsEnum will be listed in ascending value. The expected input is a whole number. If the input is invalid then the value will be rejected and the same coin value will be presented until a valid input is received.

Example setup

Please enter the number of each of the coins for the float
0.01: 100
0.02: 100
0.05: 100
0.10: 100
0.20: 100
0.50: 100
1.00: 100
2.00: 100

Usage

Enter the total value of the products being purchased. Then enter the value of coins used to pay.

Example usage

Enter the cost of product:
0.99
Enter the number of each coin you paid with:
0.01: 0
0.02: 0
0.05: 0
0.10: 0
0.20: 0
0.50: 0
1.00: 0
2.00: 1
Change to pay: 1.01
Change returned:
1.00: 1
0.01: 1
Total: 1.01

Listing

To list the contents of the spent coins hopper use the hopper command

Enter the cost of product:
hopper
These are the coins in the hopper:
0.01: 0
0.02: 0
0.05: 0
0.10: 1
0.20: 1
0.50: 1
1.00: 0
2.00: 0

To list the contents of the coins still in the float use the float command

Enter the cost of product:
float
These are the coins in the float:
0.01: 99
0.02: 100
0.05: 100
0.10: 100
0.20: 100
0.50: 100
1.00: 100
2.00: 100

Exiting

Ctrl-C will work or type exit when entering a cost

Example Usage

Enter the cost of product:
exit
Goodbye

Assumptions

• Used Coins - Most common vending machines in use retain the spent coins in a hopper. These coins are not available for use in producing change for subsequent transaction.

• Decimal currancy - No currancy symbols are in use in this application to keep it generic. The assumption is that the coinage availabe is updated in the CoinsEnum class for different denominations. For none decimal based currancies, the calculation engine will need to be replaced.

• Pay with largest coins first - As this is a change machine, assume that we want to pay with the largest coins possible to be able to return the pennies when we start to run low.

• No Lombok - Assumed you wanted to see my code