CSE 1102 Fall 2009 Lab Assignment 2

Transcription

1 CSE 1102 Fall 2009 Lab Assignment 2 Objectives: When you complete this assignment you will be able to: Edit and execute a program using BlueJ and the Wheels package. Use relative positioning Place a composite object at a particular position on the screen Set-up Procedure: The following procedure explains how to set up BlueJ with Wheels on a lab machine. 1 Log onto a lab machine. 2 Create a directory for saving your course work in your account on the Z drive. 3 Copy wheels.zip, the zip file for the Wheels package, into that directory. Do not unzip it. The wheels.zip file is available in several places. It is on the CD that comes with your textbook and it is available at the textbook website, 4 Start BlueJ, which is located in the Programs/Applications folder on the lab computers. 5 Open Preferences under the Tools menu. 6 Select the Libraries tab. 7 Click the Add button. 8 Find the wheels.zip file in the Select directory or jar/zip file window and click Open. 9 At this point, the wheels.zip file should be shown under User Libraries. Click OK. 10 Quit BlueJ and restart it for this to take effect. To install BlueJ on another computer, download the Java SE Development Kit (JDK) from The current version as of 6/1/09 is JDK 6 Update 14. Then download BlueJ from The rest of the set-up procedure is the same as above. Assignment: In this assignment you will create and run the program FirstApp.java. The text of the program is below. First, you must create a project for the program. In BlueJ select Project and then New Project. Give the project the name Lab 1 and click Create. An empty project appears with a document. Click on New Class, name the file FirstApp, double-click on the box labeled FirstApp to open the editor, and enter the program. Click on the Compile button to compile your program. After it compiles successfully, click on the Close button. To run the program, right-click on the FirstApp box, select void main (String [] args), and then click on OK. The program runs in another window, which probably opens in the background. You can move the program to the foreground by clicking the Java icon button (a

2 steaming coffee cup) at the bottom of your screen. It should look like this: Congratulations! You have successfully run your first Wheels program. Now let s make some changes to the program. 1. Immediately under the statement declaring the ellipse, insert the statement: wheels.users.rectangle _rectangle; 2. Immediately before _ellipse = new wheels.users.ellipse();add: _rectangle = new wheels.users.rectangle(java.awt.color.blue); 1 Recompile and execute the program. Examine the output. 2 Move the line that instantiates _rectangleto be immediately after the line that instantiates _ellipse. 3 Recompile and execute the program. Examine the output and explain the differences. 4 Submit the final program (all files as a zip file) using HuskyCT's assignment tool. Create a new project consisting of one class named Octave. Copy and paste the code at the end of this assignment into this new class. Compile and run this Java program as you did the previous Wheels example. The program displays one octave of piano keys as shown below.

3 Now let s modify this program. Add a class called Keyboard to this project. We will create a keyboard consisting of two octaves. Add two class variables to the Keyboard class of type Octave. The constructor for the Keyboard class should instantiate these Octave variables. You will have to move the public static void main method to the Keyboard class and change the variable names so that they make sense in this new class. Unfortunately, the Octave class always places the keys of the octave in the same place. Our two octaves are drawn on top of each other so only one is visible! We will have to write a setlocation method for the Octave class which will position all of the keys in the proper place (one octave next to the other). (Hint: You may want to move the setlocation instructions currently in the constructor to this new method and invoke the new setlocation method from the constructor.) Your final program should produce something that looks similar to the following:

4 Grading: This lab assignment is worth 8 points when completed correctly (including one point for attendance). You are free to get whatever help you need in lab class to complete the assignment correctly, short of having someone else do it for you or copying someone else's work. If you are unable to turn the work in during the lab class, you must complete it and submit it by 11:59PM that evening. /* * Chapter 1: FirstApp.java * Displays a red circle on a white background. */ * The keyword extends will be explained in Chapter 3. public class FirstApp extends wheels.users.frame { private wheels.users.ellipse _ellipse; public FirstApp () { _ellipse = new wheels.users.ellipse(); //magic to let FirstApp execute public static void main(string[] args) { FirstApp app = new FirstApp();

5 /* * Chapter 2: Octave.java * Displays an octave of piano keys */ import wheels.users.*; public class Octave extends Frame { private Rectangle _C,_D,_E,_F,_G,_A,_B; private Rectangle _CSharp, _DSharp, _FSharp, _GSharp, _ASharp; private int _XLocation, _YLocation; public Octave() { _XLocation = 100; _YLocation = 100; _C = new Rectangle(); _C.setLocation(_XLocation, _YLocation); _C.setSize(30, 100); _C.setColor(java.awt.Color.black); _C.setFillColor(java.awt.Color.white); _D = new Rectangle(); _D.setLocation(_XLocation+30, _YLocation); _D.setSize(30, 100); _D.setColor(java.awt.Color.black); _D.setFillColor(java.awt.Color.white); _E = new Rectangle(); _E.setLocation(_XLocation+60, _YLocation); _E.setSize(30, 100); _E.setColor(java.awt.Color.black); _E.setFillColor(java.awt.Color.white); _F = new Rectangle(); _F.setLocation(_XLocation+90, _YLocation); _F.setSize(30, 100); _F.setColor(java.awt.Color.black); _F.setFillColor(java.awt.Color.white); _G = new Rectangle(); _G.setLocation(_XLocation+120, _YLocation); _G.setSize(30, 100); _G.setColor(java.awt.Color.black); _G.setFillColor(java.awt.Color.white); _A = new Rectangle(); _A.setLocation(_XLocation+150, _YLocation); _A.setSize(30, 100); _A.setColor(java.awt.Color.black); _A.setFillColor(java.awt.Color.white); _B = new Rectangle(); _B.setLocation(_XLocation+180, _YLocation); _B.setSize(30, 100); _B.setColor(java.awt.Color.black);

6 _B.setFillColor(java.awt.Color.white); _CSharp = new Rectangle(); _CSharp.setLocation(_XLocation+20, _YLocation); _CSharp.setSize(20,60); _CSharp.setColor(java.awt.Color.black); _CSharp.setFillColor(java.awt.Color.black); _DSharp = new Rectangle(); _DSharp.setLocation(_XLocation+50, _YLocation); _DSharp.setSize(20,60); _DSharp.setColor(java.awt.Color.black); _DSharp.setFillColor(java.awt.Color.black); _FSharp= new Rectangle(); _FSharp.setLocation(_XLocation+110, _YLocation); _FSharp.setSize(20,60); _FSharp.setColor(java.awt.Color.black); _FSharp.setFillColor(java.awt.Color.black); _GSharp= new Rectangle(); _GSharp.setLocation(_XLocation+140, _YLocation); _GSharp.setSize(20,60); _GSharp.setColor(java.awt.Color.black); _GSharp.setFillColor(java.awt.Color.black); _ASharp= new Rectangle(); _ASharp.setLocation(_XLocation+170, _YLocation); _ASharp.setSize(20,60); _ASharp.setColor(java.awt.Color.black); _ASharp.setFillColor(java.awt.Color.black); public static void main ( String[] argv ) { Octave MyOctave = new Octave();