Lab: Abstraction and Encapsulation window.onload = function() { /** * The parameter for the start() method defines the width of the * navigation pane. * If the parameter is omitted a default value of 12em is used. */ Start.start("14em"); }; This exercise will give you practice coding Java in the matrix application discussed in class. (See Abstraction and Encapsulation Lecture on menu to the left.) This application makes use of the abstraction and encapsulation features of Java. This exercise will serve as the foundation for a later assignment on encapsulation and unit testing. To begin, download this zipped folder to an appropriate location on your machine and unzip (extract) it: Matrix.zip. This will produce a folder Matrix with subfolders src and test. Create a Project Your Job Submission Provided Files Abstraction and Encapsulation Lecture NetBeans Lab Click the File menu in the upper left corner of the IDE and select New Project... In the New Project dialog, choose Java under Categories and Java Project with Existing Sources under Projects. Click Next. Project Name and Location Add Sources Resolve Problems Project Structure Test the Project Run the GUI Name the project Matrix and choose as location the unzipped Matrix folder. Click Next. Specify the src and test sub-folders from your Matrix folder as the project's existing sources. Click Finish. At this point you may get a warning like that below left. This has to do with the dependencies among modules NetBeans requires to build and run projects. Simply click Resolve Problems... then Resolve... to add the dependency and click Close. Open the handles on the Matrix project in the Projects tab and open the associated subfolders. The structure must look like this: Right click the MatrixTest.java node and choose Run File. Upon opening the Test Results window you should see the results below. The gui package in the source folder contains classes that display matrix contents and allow the user to perform various actions and operations. Similarly, the gui package in the test folder contains classes that launch the matrix display windows. Run the MatrixControlTest class to display an empty 3×3 matrix. The display allows manual entry of elements. The image at the lower left shows the matrix after the user has typed in some values and clicked the Actions choice box. Most actions will be implemented by you in a later assignment, but the Clear action (which was given a default implementation in the Matrix interface) will work and produce the display at the lower right. The underlying data representation of matrices so far have been two-dimensional, basic Java arrays of integers. This implementation is complete and provided for you in ArrayImplementation.java. Array implementations, though efficient, are not flexible. For example, arrays are fixed size and cannot grow if required. Because of the way that the matrix project has been designed, we have the following advantages: It is straightforward to "swap out" the underlying array representation for one based on Java lists, i.e. ArrayListImplementation Only a simple change has to be made to the Matrix interface No changes have to be made to the AbstractMatrix implementation of Matrix No changes need to be made in MatrixTest to test the new implementation This section will guide you through the new implementation. Change create Method Complete the Implementation Rerun the Tests First, change the definition of the static create method in the Matrix interface from: to: Now run the MatrixTest and MatrixControlTest files again. Since the ArrayListImplementation class is incomplete, neither will work. Note the locations in ArrayListImplementation.java where comments indicate you must add code. Note also the similarities between ArrayImplementation and ArrayListImplementation: Both extend AbstractMatrix, which implements Matrix. Both implement the get and set methods from the Matrix interface. The major difference is the underlying data representation, which affects the constructor and methods. To understand this implementation, you will need to be familiar with Java's List interface and ArrayList class. Documentation can be found in the java.util package in the Java 8 API Specification. Data Representation Constructors Methods The major difference is the underlying data representation: In ArrayImplementation the matrix elements are represented using: In ArrayListImplementation it should be: Note how the ArrayImplementation constructor creates the two-dimensional elements array: Similarly, the ArrayListImplementation constructor must create a list of lists and initialize all elements to zero. The top-level list has size equal to the number of rows, and each element of this list has a size equal to the number of columns. The top-level list should be constructed with: and a loop will need to similarly create internal lists. The required methods get and set will be similar. Note ArrayImplementation's use of checkBounds in get and set. Since checkBounds is inherited from AbstractMatrix, it can be used in exactly the same way in ArrayListImplementation. The only difference is how the elements are accessed in the underlying data representation. When you have completed the array list implementation of matrices, run the MatrixTest.java and MatrixConsoleTest files. The results should be exactly as they were for the array implementation. The files required for the lab exercise are available from the menu on the left. (Does not include the GUI files that will be discussed at another time.) Matrix.java MatrixException.java AbstractMatrix.java ArrayImplementation.java ArrayListImplementation.java MatrixTest.java Matrix.java Note that the transpose, makeIdentity, fillRowWise, and fillColumnWise methods are not involved in this lab exercise; they will be implemented in a later assignment. MatrixException.java AbstractMatrix.java Note that the equals, add, and multiply methods are not involved in this lab exercise; they will be implemented in a later assignment. ArrayImplementation.java ArrayListImplementation.java MatrixTest.java When your matrix project is working correctly: Make sure your identifying information is in the class comments of all class files Outside of NetBeans, zip (compress) your src folder as src.zip. Note: this is not the whole NetBeans project folder — only the source code files. Submit src.zip to . Your project will be inspected and run by the lab instructor. Grading criteria: Successful running of MatrixTest and MatrixControlTest using an array implementation: 2 points Successful running of MatrixTest and MatrixControlTest using an array list implementation: 8 points Note the general Submission Policy in the menu at left. Submission Policy
