Cork Institute of Technology. Autumn Programming 2: Object-Orientation. (Time: 3 hours)

Transcription

1 Cork Institute of Technology Bachelor of Science (Honours) in Software Development - Stage 2 (KSDEV_8_Y2) Autumn 2008 Programming 2: Object-Orientation (Time: 3 hours) Answer 7 questions from Section A. Answer 2 questions from Section B. Consult Appendix A when answering questions that involve writing Java Code. Examiners: Dr. M. O Cinneide Mr. M. Donnelly Mr. R. Miller

2 Section A 1) Write a note on each of the following: Information Hiding Object diagrams Java Interfaces 2) Give a description of the following: Inheritance Coupling Polymorphic collections 3) Describe the different types of access that can be specified for elements of a Java class. 4) What is a Layout manager? Describe the characteristics of the following layout managers: BorderLayout GridLayout FlowLayout Are there any problems associated with the manual positioning and sizing of components? 5) What do you understand by the term event-driven? What is an event-driven program doing when a user is not interacting with it? Explain what an inner class is, show, with a code example, how it helps when writing event-handlers. 6) Describe how an applet works; include in your answer a description of the different methods an applet uses during its lifecycle. 7) Write the paintcomponent() method for a JPanel that has the following appearance:

3 8) Write the code for the constructor of the RadioButtonDemo class: 9) Write the code for this application, which displays a simple animation. The animation uses the following sequence of images: To set the animation going, press the play button

4 Section B Q.1 Write the code for the simple game described below: Players must try and guess a secret number within a specified range e.g Players are allowed five attempts at guessing the number: Type in the number and then press the guess button If the guess is lower than the secret number, the background colour of the text-field turns blue: If the guess is higher than the secret number, the background colour of the text-field turns red: The game finishes with either the player guessing the correct number or the player losing all their lives: The reset button resets the game so that the user can play again (25 marks)

5 Q.2 Study the following class diagram, which was developed for a simple staff payroll system: PayRollSystem -Stafflist[] : Employee +PayRollSystem() +calculatewagebill() : float +addemployee(in emp : Employee) : void +printemployeelist() : void Employee -name : String -id : String -status : int +Employee(in name : String, in id : String, in status : int) +<abstract>calculatepay() : float +getname() : String +getid() : String +getstatus() : int UserInterface PartTimeEmp -HourlyRate : float -hoursperweek : int +PartTimeEmp(in name : String, in id : String, in status : int) +calculatepay() : float +sethours(in hours : int) : void +setrate(in rate : float) : void FullTimeEmp -salary : float +FullTimeEmp(in name : String, in id : String, in status : int) +calculatepay() : float +setsalary(in salary : float) : void Write the code for the following classes: PayRollSystem The super-class Employee and its sub-classes: FulltimeEmp and PartTimeEmp. (25 marks) Q.3 Please consult appendix B. Below is the screenshot of a calculator application. Building on the source code supplied in Appendix B, You are required to write the code that makes all the buttons fully functional. (25 marks)

6 Appendix A (classes other than those listed below may be required when answering questions) JTabbedPane: addtab(string title, Component component) setselectedindex(int index) Graphics: setcolor(color c) filloval(int x, int y, int width, int height) drawoval(int x, int y, int width, int height) fillrect(int x, int y, int width, int height) ImageIcon: ImageIcon(String filename) ButtonGroup: ButtonGroup() add(abstractbutton b) BorderFactory createemptyborder(int top, int left, int bottom, int right) createlineborder(color color, int thickness) JList JList(Object[] listdata) JList(Vector listdata) Int getselectedindex() Object getselectedvalue() Menus JMenu(String s) add(jmenuitem menuitem) JMenuBar() add(jmenu c) JMenuItem(String text, Icon icon) JMenuItem(String text) Layout Managers GridLayout(int rows, int cols) GridLayout(int rows, int cols, int hgap, int vgap) CardLayout() show(container parent, String name) BorderLayout() BorderLayout(int hgap, int vgap) Timer Timer(int delay, ActionListener listener)

7 APPENDIX B import java.awt.*; import java.awt.event.*; import javax.swing.*; public class MyCalculator extends JFrame Container c; JButton[] numberbuttons = new JButton[10]; JButton add; JButton multiply; JButton divide; JButton subtract; JButton point; JButton equals; JButton clear; JPanel gridpanel; JTextField textfield; public MyCalculator() super("calculator"); c = getcontentpane(); gridpanel = new JPanel(); gridpanel.setlayout(new GridLayout(4,4)); textfield = new JTextField("0.0"); textfield.sethorizontalalignment(jtextfield.right); ActionHandler handler = new ActionHandler(); for (int i=0;i<10;i++ ) numberbuttons[i] = new JButton(Integer.toString(i)); numberbuttons[i].addactionlistener( handler ); numberbuttons[i].setactioncommand(integer.tostring(i)); add = new JButton("+"); add.addactionlistener( handler ); add.setactioncommand("add"); multiply = new JButton("*"); multiply.addactionlistener( handler ); multiply.setactioncommand("multiply"); divide = new JButton("/"); divide.addactionlistener( handler ); divide.setactioncommand("divide"); subtract = new JButton("-"); subtract.addactionlistener( handler ); subtract.setactioncommand("subtract"); point = new JButton("."); point.addactionlistener( handler ); point.setactioncommand("point"); equals = new JButton("="); equals.addactionlistener( handler ); equals.setactioncommand("equals");

8 clear = new JButton("C"); clear.addactionlistener( handler ); clear.setactioncommand("clear"); gridpanel.add(numberbuttons[1]); gridpanel.add(numberbuttons[2]); gridpanel.add(numberbuttons[3]); gridpanel.add( add ); gridpanel.add(numberbuttons[4]); gridpanel.add(numberbuttons[5]); gridpanel.add(numberbuttons[6]); gridpanel.add( subtract ); gridpanel.add(numberbuttons[7]); gridpanel.add(numberbuttons[8]); gridpanel.add(numberbuttons[9]); gridpanel.add( multiply ); gridpanel.add( point ); gridpanel.add(numberbuttons[0]); gridpanel.add( equals ); gridpanel.add( divide ); c.add( textfield, BorderLayout.NORTH ); c.add( gridpanel, BorderLayout.CENTER ); c.add( clear, BorderLayout.SOUTH ); private class ActionHandler implements ActionListener public void actionperformed(actionevent actionevent) public static void main( String args[]) JFrame calc = new MyCalculator(); calc.show(); calc.pack();