EECS1022-Lab 5 Single Class, Attributes, Methods & JUnit Tests Solved

1         Task 1: Complete Weekly Java Tutorial Videos
•    For Lab5, you are assigned to study Week 6 Part A to Part D of the Java tutorial series:

https://www.youtube.com/playlist?list=PL5dxAmCmjv_70YmHrdPYD809c6OeIixvV To reference tutorial videos from the previous weeks, see:
 
https://www.youtube.com/playlist?list=PL5dxAmCmjv_6wy2m0yq2wObIWPz4tAxW6
 
These Java tutorial videos assigned to you are meant for you to:

1.   Obtain extra hands-on programming experience on Java, supplementing your weekly lectures.

2.   Complete the lab assignment with the necessary skills and background.

Though we do not require the submission of the weekly Java tutorial project (like in Lab0), examples and insights discussed in these tutorials will be covered in your (written and programming) tests and exam: should you decide to skip the weekly tutorial videos, it would be your choice.

As you study through the example Java classes in the tutorial videos, you are advised to type them out (but absolutely feel free to add new Java classes to experiment) on Eclipse.

•    You can find the iPad notes of illustrations from the tutorial videos here:

https://www.eecs.yorku.ca/˜jackie/teaching/tutorials/notes/EECS1022%20Tutorial%20on%20Java.pdf

Getting Prepared for Programming Test 3

•    Your Programming Test 3 will cover classes and objects, and its format will be (virtually) identical to this lab (and Lab6).

2         Task 2: Complete Programming Exercises
Starting Task 2 should mean that you have already completed the weekly Java tutorial videos (Section 1).

2.1        Step 1: Download and Import the Starter Project
1.   Download the Eclipse Java project archive file from eClass: EECS1022W21Lab5.zip

2.   Launch Eclipse and browse to EECS1022-W21-workspace as the Workspace then click on Launch, e.g.,

 

3.3 Choose Select archive file. Make sure that the EECS1022W21Lab5 box is checked under Projects.

 

2.2        Step 2: Programming Tasks
From the Package Explorer of Eclipse, your imported project has the following structure.

•    The consoleapps package is empty. You may add new console application classes here to test the implemented methods if you wish. However, these added console application classes will not be graded.

•    It is expected that the TestVendingMachine JUnit class contains compilation errors. This is because that declarations and definitions of the required class(es) and method(s) it references are missing.

 

•    The model package is empty. Class(es) and method(s) derived from the given JUnit class must be added to this package. Class(es) added to a package other than model will not be graded.

Therefore, your tasks are:

1.   Inferring from the given JUnit tests, add the missing class(es) and method(s) into the model package. For example, if you add class Foo in the model package, make sure that you write a line in the beginning of the TestVendingMachine class (after the line package junittests;):

import model.Foo;
2.   Pass all JUnit tests given to you (i.e., a green bar).

To run them, as shown in the Java tutorials on Week 1, right click on TestVendingMachine.java and run it as JUnit tests. Of course, none of the given tests would pass to begin with.

You must not modify these given JUnit tests, as they suggest how the intended class(es) and method(s) should be declared.

How to Deal with a Failed JUnit Test? From the JUnit panel from Eclipse, click on the failed test, then double click on the first line underneath Failure Trace, then you can see the expected value versus the return value from your implemented method.

2.3        The Vending Machine Problem
You are required to develop an object-oriented program solving a (simplified) vending machine (VM) problem:

•    There are four products offerred (attend to the exact spellings):

–    “Coke”

–     “Orange Juice”

–    “Kitkat Chunky Bar”

–    “Lay’s Classic Chips”

In case you are a big fan of M & M’s chocolate bags: unfortunately, the kind of VMs under consideration does not offer them!

•    The VM’s LED screen displays the status of the VM:

–    When first created, the status is "Empty VM Started"

–    The status only changes when the add or dispense operation (described below) is invoked.

•    Given an VM instance, say vm, there are five operations supported:

–    Check the status of the current VM: vm.checkStatus().

–    Check the stock of the current VM: vm.checkStock().

Given a product name:

–    Add units to its stock, e.g., vm.add("Coke", 5)

–    Dispense units from its stock, e.g., vm.dispense("Coke", 2) – Check its current stock, e.g., vm.checkStock("Coke")

•    Input names to the add and dispense operations may be invalid, in which case you need to return error messages accordingly.

•    Input units to the add and dispense operations are always valid: you need not worry about non-positive or too-large values.

2.4        Hints and Requirements
•    See this notes on how to infer classes and methods from given JUnit tests:

https://www.eecs.yorku.ca/˜jackie/teaching/lectures/2021/W/EECS1022/notes/EECS1022_Inferring_ Classes_and_Methods_from_JUnit_Tests.pdf

Programming IDEs such as Eclipse are able to fix such compilation errors for you. However, you are advised to follow the guidance as specified in the notes to fix these compilation errors manually, because: 1) it helps you better understand how the intended classes and methods work together; and 2) you may be tested in a written test or exam without the assistance of IDEs.

•    Any new class(es) you add must reside in the model package.

–    Once the necessary class(es) and method(s) are declared, you can add as many attributes as necessary to implement the body of each method.

–    Study carefully example usages of a VM instance as specified in TestVendingMachine.java: they suggest the how the intended class(es) and method(s) should be declared and implemented.

–    Focus on gradually passing one test at a time.

–    You cannot use any Java library classes (e.g., ArrayList) or methods for implementation. That is, there must not be any import statement in the class(es) you add to the model package.