Laboratory Activity 5: First Look at Classes

Transcription

1 Laboratory Activity 5: First Look at Classes 1 Introduction The software company that you have been working for has asked you to developing a program that will be used by a Car Dealer. As the first stage of this project, you have been assigned to create a Car class that will contain the basic information about all the cars that the Dealers sells. Another person in your company will develop the GUI interface application that will extensively use your Car class (like a soap opera on TV, there will be a future drama here and you will eventually do the GUI too, but this is later in this semester, not in today s episode ). While this GUI is not ready, you will be testing your class in a terminal window type program that you must develop yourself. 2 Main Features of a Car When creating a new class, like a Car, you need to ask the customer what are the major features that they want to have in a car, so that we can translate those features into a program/class. It is important to have an open channel with the customer in the initial phase of your project, so that when you finally deliver your product to the customer they are hopefully satisfied with the product and there are no unpleasant surprises, such as it is not what we were expecting. After few meetings with the customer, the following list of car features are expected to be handled by your application: Price Color Model Accessories Each of the features above have different values, depending on the car model. This Car Dealer only works with Corolla, Camry, and Sienna cars. And for each of those car models, this dealer works only with a selection of built years, colors, and accessories, as shown in Section 3 on the next page.

2 3 Types of Cars normally found in the Car Dealer store Your program shall allow the dealer to create the following cars Year Range: Price Range: $18000 $20000 Available Colors: Black, Blue Accessories: none Car Model: Camry Year Range: Price Range: $20000 $22000 Available Colors: Red, White Year Range: Price Range: $25000 $30000 Available Colors: Silver, Black Standard Accessories: Media Player, heated seat 4 Code Development The Car Dealer application that you are about to develop has two main parts: a Java Class called Car, which will contain all the fields (car characteristics) discussed in Section 2, and a main program that will use this Car class to create car objects (the actual cars for sale). Remember that the Car class is just a blue print of a car; the car object can be created by using this blue print with the command that involves the new keyword. 4.1 Create Your Netbeans Project As you have done multiple times already in this course, create a new NetBeans project called CarDealerApp. Before start coding inside the CarDealerApp java file itself, let s first create a Car Class (see Section 4.2 below), since the CarDealerApp uses the Car class to create new car objects. 4.2 Create the Car Class inside the CarDealerApp In the project, create a new Java Class called Car. To do so, right click your mouse when its pointer is on your program source package (if you have used CarDealerApp as your project name, then your package name should cardealerapp. Right click on that package) >> New >> Java Class and then name this new class as Car >> Finish.

3 4.2.1 Create the class fields In this class, create class fields (variables) that will hold the Car Model, year, price, available colors, default color, standard accessories, and optional accessories. Think about their types when creating these fields. Just to practice our understanding about using Java arrays, please use arrays when defining ranges, such as price range: double[] pricerange; // where the first item would hold the lowest value and the second item the highest value in the range. Do the same for colors, accessories, and build year ranges shown in Section Create the class methods As part of our pursue of happiness, opss I mean the pursue of data encapsulation, create setters and getters for all the class fields. Sections and discuss details of these methods The setter methods The following setter methods shall be created in the Car class. setcolor() can only change the car color is the new color requested is one of the available colors for the given car model, e.g., for Camry only Red and White colors are acceptable when requesting a car color change. However this list of color changes for Corolla and Siena. Your code implementation should handle these differences. setyear(): the Dealer had told you that they deal with cars only certain range of year built, and this range change based on the car model, therefore your setyear() must reflect/check/validate that. setprice(): same comment as in setyear(). setaccessories():same comment as in setyear() The getter methods Very similar to the getters, however the getters just return info while the setters set data into a given Car object Create a Car Constructor For this exercise, you are required to create only the non default constructor (i.e., the constructor that takes input arguments). This constructor will require the following inputs: type of car, its color, built year, and its tag price. Here is an example of the command to create a new Car object from within the CarDealerApp: Car car01 = new Car("Corolla", 2016, 18500, "Blue"); Create a printinfo() Method A method called printinfo() shall be created. When this method is called, it shall print the car info into the terminal window, as shown in the example below. Built Year: 2015 Tag Price: $15000

4 4.3 CarDealerApp Implementation Now that you have created the Car Class, it is time to work in the CarDealerApp file. Sections through give details on what needs to be done Current Available Car for Sale The CarDealerApp shall create cars that the dealer currently has for sale. The table below contains all the information you need. In a real application, this info would come from a text file, or database, or GUI. For this lab you will hard code the creation of those elements (so that every time we run this program we will get the same results). Create the cars in the same manner as shown in Section Car ID Car 01 Car 02 Car 03 Car 04 Car 05 Model Corolla Corolla Camry Camry Sienna Year Asked Price Color Blacl Blue Red White Silver Make an array of Available Cars Make an array of available cars. The process of creating an array of Cars is very similar to the way of creating an array of integers or doubles. Your app will use this array to print out the cars that are currently available in the Car Dealer Store by looping over the array General App functionality After your program creates the 5 cars listed in the Table above (in the background, the user wouldn t see it), your app shall present a menu in the terminal window as shown below: Choose Option: 1: list of available cars 2: Choose car 3: Exit Where: choosing 1 makes the application to show all the available cars in the dealer store, choosing 2 makes the application to prompt the user to select one of the available cars (1 for the first, 2 for the second, etc.); and 3 will exit the application Buying a given car If the buyer select option 2 above, and select a given car, let s say the first one in the table in Section 4.3.1, the app then will display the car features as shown below: Year: 2016 Price: $18500 Accessories: none And then it should prompt the user the following question: Make your best offer. If the offer is in the price range shown in Section 3.0, then accept it and make the deal; otherwise tell the customer to make a better offer and provide the allowed price range for them. Keep asking until either the user enters a price in the car range price or if the user enters 1.

5 4.3.5 General Application Checks While creating the main application, if the programmer tries to create a car outside the ranges of the Table shown in the Section 3.0, your Car class should complain about it and for now let s make the program to quit after issuing a meaningful error message. For this lab, your application should check for valid color, year, color, and tag price when the car is created. Remember that those features are car model dependent, e.g., valid colors for one car model, such as Corolla, are different for Camry and Sienna cars. Their specific ranges are given in the Table shown in Section 3. 5 Testing the Application It is imperative that you, as a developer, exhaustively test your application, verifying that it performs as intended. Sections 5.1 to 5.X describe the minimum tests and acceptance criteria for this application. 5.1 Test 01: Listing Available Cars for Sale If the user selects option 1 list of available cars), your application should print the following output: Built Year: 2016 Tag Price: Accessories: None Tag Price: Color: Blue Accessories: None Car Model: Camry Built Year: 2016 Tag Price: Color: Red Car Model: Camry Built Year: 2015 Tag Price: Color: White Tag Price: Color: Silver Accessories: Media Player, Heated Seats

6 5.2 Test 02: Bad Car Model In the CarDealerApp, place this command Car car01 = new Car("Rav4", 2016, 18500, "Black"); The CarDealerApp shall error off with a meaningful message, such as: This dealer doesn't work with this car model: Rav4 5.3 Test 03: Bad Built Year, Price, and Color In the CarDealerApp, place this command Car car01 = new Car("Corolla", 2000, 10, "Orange"); The CarDealerApp shall error off with a meaningful message for each of those invalid values: This dealer doesn't work with this car model: Rav4 Note: instead of creating a single Car object with all possible errors, you can test your app by creating multiple cars, and in each of them you place just one invalid value. It is up to you. Example: If you create a car using the following command: Car car07 = new Car("Corolla", 2000, 100, "Green"); Your app should issue the following warning messages: Unfortunately we do not work with Corolla in the given year: 2000 We work with cars from 2016 to 2018 We cannot sell the car for the requested price of The color Green that you have requested is not available for car model: Corolla The available colors are: Black, Blue

7 5.4 Buying a car Choose option 2 Choose car from the menu shown in Section Then select Sienna. Your program should prompt the user to give his/her best offer. Input and you should get that you got the car! Congratulations. Pay attention that the final printout shall have the new tag price instead of the original value! Choose the car you've liked: 5 Tag Price: Color: Silver Accessories: Media Player, Heated Seats Give your best offer: Deal! Sold! Tag Price: Color: Silver Accessories: Media Player, Heated Seats Now, try it again and offer a very low value for the car. You should get a message like this: Choose the car you've liked: 1 Built Year: 2016 Tag Price: Accessories: None Give your best offer: 10 Your best offer is outside the allowed range The range for Corolla is between $ and $