Introduction This assignment will ask that you write a simple graphical user interface (GUI).

Transcription

1 Computing and Information Systems/Creative Computing University of London International Programmes : Graphical Object-Oriented and Internet programming in Java Coursework one Introduction This assignment will ask that you write a simple graphical user interface (GUI). Assignment learning objectives Understand how a JFrame represents a window on the screen Understand how to add components to the JFrame's content pane Understand how an application must listen for a GUI event Understand how to add a listener to a component Understand in general how to implement an Interface Understand in particular how to implement the ActionListener Interface Understand how to use the ActionPerformed method Reading for assignment You should have read volume one of the subject guide including all recommended readings, with particular reference to chapter 12, of Head First Java pages , and chapter 11 of the subject guide. Marks for assignment The marks for each section of the assignment are clearly displayed against each question and add up to 25. There are another 25 marks each available from the second, third and fourth assignments. Deliverables A print out of your two programs: SimpleGUI.java and MyGUI.java Electronic versions of your two programs: SimpleGUI.java and MyGUI.java A paragraph in answer to question (c)

2 Coursework one Consider the program, First, below: import javax.swing.*; import java.awt.*; import java.awt.event.*; public class First { } public static void main (String[] args) { First thing = new First(); thing.go(); } public void go() { JFrame frame = new JFrame(); frame.setsize(500,500); frame.setvisible(true); frame.setdefaultcloseoperation(jframe.exit_on_close); } Compile and run this program. You should note that when run the program displays a 500 by 500 window on the screen to the user. (a) Rewrite the program, calling your new program SimpleGUI. In your new program implement the following: (i) (ii) (iii) (iv) Add a JButton to the frame that displays the text coursework one Implement ActionListener Register the JButton with the ActionListener Make the JButton display the text You clicked me! if the user clicks it. [3 marks] [3 marks] [3 marks] [3 marks] You should now have a very simple GUI, that displays a button in a frame to the user. The button displays the text coursework one which changes to You clicked me! if the user clicks the button. However subsequent clicks by the user will have no further effect on the display. (b) Rewrite your program, this time calling it MyGUI. In your new program each time the user clicks on the JButton it will randomly display one of the following statements: [9 marks]

3 Click me you know you want to. One click good, two clicks bad. Why did the chicken cross the road? To get to the other side! The difference between genius and stupidity is that there is a limit to genius. What has been clicked cannot be unclicked. If you believe there is hope then there is hope. To click or not to click that is the question. The click is out there. (c) Explain how the actionperformed() method gets called, and why it is that you do not have to explicitly call it in your code. [4 marks]

4 UNIVERSITY OF LONDON DIPLOMA AND BSc IN COMPUTING AND RELATED SUBJECTS FOR INTERNATIONAL PROGRAMMES STUDENTS COURSEWORK SUBMISSION FORM IMPORTANT, PLEASE NOTE: You must complete this form in full and attach it to the coursework that is to be submitted to the University. Full name:... (as it appears on your Registration Form) Student number:... Unit title:... Unit number:... Assignment number:... DECLARATION I declare that: I understand what is meant by plagiarism. I understand the implications of plagiarism. This assignment is all my own work and I have acknowledged any use of the published or unpublished works of other people. Signature Date

5 UNIVERSITY OF LONDON DIPLOMA AND BSc IN COMPUTING AND RELATED SUBJECTS FOR INTERNATIONAL PROGRAMMES STUDENTS COURSEWORK SUBMISSION CHECKLIST Before you submit your coursework to the University, have you: completed the title, unit number and assignment number on the submission form? signed and dated the Declaration? put your name and student number on every page? put the unit number, unit name and assignment number on every page? used more than one page? If so, have you securely stapled or tied the pages together? used a disk? If so, have you used a separate disk for each assignment? (Note: you should only use a disk if it is explicitly asked for in the assignment). labelled clearly and securely attached any disks? attached all parts of the coursework required (including the submission form)? If you fail to do these things your coursework may not be accepted. Please send all coursework to: The Registration and Learning Resources Office Room STG13 Stewart House University of London 32 Russell Square London WC1B 5DN United Kingdom Tel: +44 (0) Fax: +44 (0)

6 Computing and Information Systems/Creative Computing University of London International Programmes : Graphical Object-Oriented and Internet programming in Java Coursework two Introduction This assignment asks you to write a basic graphical program, and a graphical program with a simple animation. Assignment learning objectives Understand the form of the most basic graphical program Understand how to subclass JPanel and override paintcomponent() in order to draw graphics Understand what the argument to paintcomponent() is and that only the JVM can construct this object Cast the Graphics object to a Graphics2D object in order to invoke the methods from the Graphics2D library Understand how to use Thread.sleep in an animation to halt the program for a given time interval between frames Reading for assignment You should have read volume one of the subject guide including all recommended readings, with particular reference to chapter 12 of Head First Java, pages , and chapter 12 of the subject guide. Marks for assignment The marks for each section of the assignment are clearly displayed against each question and add up to 25. There are another 25 marks each available from the first, third and fourth assignments. Deliverables Print outs of your four programs: MyDrawPanel.java; SimpleDrawing.java; RandomDrawPanel.java and RandomDrawing.java. Electronic versions of your four programs: MyDrawPanel.java; SimpleDrawing.java; RandomDrawPanel.java and RandomDrawing.java.

7 Coursework two (a) (b) (c) (d) (e) (f) Write a class MyDrawPanel that extends JPanel and overrides paintcomponent(). The paintcomponent() method should display a blue oval with the coordinates (225, 225, 50, 50). Write a program called SimpleDrawing.java. Your program should display a 500 x 500 JFrame. Add a MyDrawPanel object to the frame such that when the program is run the blue oval is displayed. Write a class BigBlueDrawPanel.java that extends JPanel and overrides paintcomponent(). The paintcomponent() method should first create a blue oval with the coordinates (225, 225, 50, 50). Each time the paintcomponent() method is run the coordinates (50, 50) should increase by 2 so that the oval gradually increases in size. Use Thread.sleep to slow the growth of the oval so that the user will be able to clearly see it getting bigger. Write your code so that the coordinates are adjusted each time the oval is drawn such that the centre of the oval stays in the same place each time. Write a class BigBlueDrawing.java that uses BigBlueDrawPanel.java to display the blue oval in a 500 x 500 JFrame. The blue oval should gradually increase until the JFrame is completely filled with the colour blue. [5 marks] [5 marks] [4marks] [1 mark] [5 marks] [5 marks]

8 UNIVERSITY OF LONDON DIPLOMA AND BSc IN COMPUTING AND RELATED SUBJECTS FOR INTERNATIONAL PROGRAMMES STUDENTS COURSEWORK SUBMISSION FORM IMPORTANT, PLEASE NOTE: You must complete this form in full and attach it to the coursework that is to be submitted to the University. Full name:... (as it appears on your Registration Form) Student number:... Unit title:... Unit number:... Assignment number:... DECLARATION I declare that: I understand what is meant by plagiarism. I understand the implications of plagiarism. This assignment is all my own work and I have acknowledged any use of the published or unpublished works of other people. Signature Date

9 UNIVERSITY OF LONDON DIPLOMA AND BSc IN COMPUTING AND RELATED SUBJECTS FOR INTERNATIONAL PROGRAMMES STUDENTS COURSEWORK SUBMISSION CHECKLIST Before you submit your coursework to the University, have you: completed the title, unit number and assignment number on the submission form? signed and dated the Declaration? put your name and student number on every page? put the unit number, unit name and assignment number on every page? used more than one page? If so, have you securely stapled or tied the pages together? used a disk? If so, have you used a separate disk for each assignment? (Note: you should only use a disk if it is explicitly asked for in the assignment). labelled clearly and securely attached any disks? attached all parts of the coursework required (including the submission form)? If you fail to do these things your coursework may not be accepted. Please send all coursework to: The Registration and Learning Resources Office Room STG13 Stewart House University of London 32 Russell Square London WC1B 5DN United Kingdom Tel: +44 (0) Fax: +44 (0)

10 Computing and Information Systems/Creative Computing University of London International Programmes : Graphical Object-Oriented and Internet programming in Java Coursework three Introduction This assignment asks that you write three GUIs, each with one drawing and one, two or three buttons. The components should be laid out using the BorderLayout manager, and inner classes should be used to implement ActionListener such that each button has a different effect on the drawing when clicked. Assignment learning objectives Understand how layout managers control the size and location of nested components Understand that the layout manager of the background component determines the size and location of the added component Understand how the layout manager uses the preferred size of the added component for its calculations Understand that whether or not this size is respected depends on the layout manager's policies Use BorderLayout manager to add components to one of five background regions Understand that in this case components in the north and south get their preferred heights, but not width; the situation is reversed for the east/west regions; and the component in the middle gets whatever is left over, unless you use pack() Understand that BorderLayout if the default manager for a frame and FlowLayout is the default for a panel Reading for assignment You should read volume two of the subject guide with particular reference to chapter 4, and Chapters 12 and 13 of Head First Java, particularly pages and pages Marks for assignment The marks for each section of the assignment are clearly displayed against each question and add up to 25. There are another 25 marks each available from the first, second and fourth assignments. Deliverables Print out of your programs, GrowCircle.java, GrowAndShrinkCircleGUI.java and ChangeColorCircleGUI.java Electronic version of your programs, GrowCircle.java, GrowAndShrinkCircleGUI.java and ChangeColorCircleGUI.java

11 Coursework three Write the following programs: (a) Write a program called GrowCircle.java that will display a 500 x 500 JFrame. [2 marks] (b) (c) (d) (e) (f) (g) (h) (i) (j) Write an inner class of GrowCircle called CircleDrawPanel that extends JPanel and overrides paintcomponent(). The paintcomponent() method should display a blue oval with the coordinates (225, 200, 50, 50). Use BorderLayout manager to place a JButton in the EAST region of the frame, and an instance of your GrowCircle class in the CENTER region. Make the JButton display the text click me to grow the circle. When compiled your program should display a blue circle next to a button that says click me to grow the circle. Actually clicking the button will have no effect on the circle. Link the JButton and the blue circle such that when the JButton is pressed the circle increases in size by a fixed amount. You may choose the amount that the circle size increases by. The changes you make to your program to implement this must include an inner class. Save your program. Save a copy of your program as GrowAndShrinkCircleGUI.java. Add another JButton to the WEST region of the new program, this one with the text click me to shrink the circle. Adjust the coordinates of the circle so that it is displayed in the middle of the frame. Link the new JButton to the circle, such that if it is clicked the size of the circle decreases by a fixed amount of your choosing. You should use another inner class for this. Save your completed program. Save a copy of your second program as ChangeColorCircleGUI.java. Change this program by adding another JButton to the SOUTH region, with the text click me to change the colour of the circle. Link the new JButton to the oval, such that when it is clicked the colour of the circle changes randomly. [2 marks] [4 marks] [2 marks] [3 marks] [2 marks] [2 marks] [3 marks] [2 marks] [3 marks] Please note: this assignment asks that candidates use very specific names for their classes, and directs that particular text is used for the JButtons. Candidates who do not follow these instructions closely may lose marks.

12 UNIVERSITY OF LONDON DIPLOMA AND BSc IN COMPUTING AND RELATED SUBJECTS FOR INTERNATIONAL PROGRAMMES STUDENTS COURSEWORK SUBMISSION FORM IMPORTANT, PLEASE NOTE: You must complete this form in full and attach it to the coursework that is to be submitted to the University. Full name:... (as it appears on your Registration Form) Student number:... Unit title:... Unit number:... Assignment number:... DECLARATION I declare that: I understand what is meant by plagiarism. I understand the implications of plagiarism. This assignment is all my own work and I have acknowledged any use of the published or unpublished works of other people. Signature Date

13 UNIVERSITY OF LONDON DIPLOMA AND BSc IN COMPUTING AND RELATED SUBJECTS FOR INTERNATIONAL PROGRAMMES STUDENTS COURSEWORK SUBMISSION CHECKLIST Before you submit your coursework to the University, have you: completed the title, unit number and assignment number on the submission form? signed and dated the Declaration? put your name and student number on every page? put the unit number, unit name and assignment number on every page? used more than one page? If so, have you securely stapled or tied the pages together? used a disk? If so, have you used a separate disk for each assignment? (Note: you should only use a disk if it is explicitly asked for in the assignment). labelled clearly and securely attached any disks? attached all parts of the coursework required (including the submission form)? If you fail to do these things your coursework may not be accepted. Please send all coursework to: The Registration and Learning Resources Office Room STG13 Stewart House University of London 32 Russell Square London WC1B 5DN United Kingdom Tel: +44 (0) Fax: +44 (0)

14 Computing and Information Systems/Creative Computing University of London International Programmes : Graphical Object-Oriented and Internet programming in Java Coursework four Introduction This assignment will ask that you modify two files in order to handle exceptions. In addition you are asked to write a class that can download the HTML source of the web page at a given url, and to write another GUI. This time your GUI will allow the user to input a url into a text field. At the click of a button the HTML source code at the given url is displayed in the text area of the GUI. Assignment learning objectives understand how all exceptions subclass java.lang.exception understand that the compiler does not check that possible runtime exceptions are handled in code understand that the compiler does care about checked exceptions, and insists that they are declared or wrapped in a try/catch block understand how a method throws an exception with the keyword throw followed by a new exceptions object understand that if your code calls a checked exception throwing method, you must either duck the exception or enclose the call in a try/catch block know that there are two types of stream: connection and chain, their functions and how they work chain a FileReader connection stream to a BufferedReader for efficient reading write a program which navigates to a given website and downloads the HTML source of the site Reading for assignment You should read: volume two of the subject guide, chapter 3 volume two of the subject guide, chapter 5 (particularly sections ) Chapter 11 of Head First Java, particularly pages , , and Chapter 12 of Head First Java, particularly pages Chapter 14 of Head First Java, particularly page 433 Marks for assignment The marks for each section of the assignment are clearly displayed against each question and add up to 25. There are another 25 marks each available from the first, second and third assignments. Deliverables Print outs of the revised ages.java and SourceViewer.java programs. Print outs of your PageSourceFinder.java and SourceTextGUI.java programs. Electronic version of all four programs. A sentence or two in answer to question (b) and a paragraph in answer to (d).

15 Coursework four Type and compile the following program. Try to run the program. You should find that while it compiles it does not run instead it reports a NumberFormatException. import java.io.*; public class ages { public static void main (String[] args) { ages ask = new ages(); ask.go("fifty"); } } (a) public void go(string s) { int a = Integer.parseInt(s); System.out.println("your age is "+a); } Add a try/catch block to the ages class (you should add and not delete or comment out any code) so that the program, when re-compiled and run will print out the message fifty is not parse-able as an integer. [3 marks] import java.io.bufferedreader; import java.io.filewriter; import java.io.ioexception; import java.io.inputstreamreader; import java.io.reader; import java.net.malformedurlexception; import java.net.url; class SourceViewer { public static void main(string args[]) throws IOException { String s = " URL u = new URL(s); Reader r = new BufferedReader(new InputStreamReader(u.openStream())); int c = 0; boolean intag = false; while ((c=r.read())!=-1) { System.out.print((char)c); } } }

16 (b) (c) (d) (e) (f) (g) (h) (i) Type and compile the above SourceViewer class. Run the program on a machine with an internet connection. Describe what the program does. Delete (or comment out) the words throws IOException from the main declaration and recompile the program. This time you should find that you have three errors. Correct the errors by using try/catch. Your revised program should have one try block and one catch block for each of the types of unreported exceptions found by the compiler. Explain why is it that the ages class would compile with unreported exceptions while the SourceViewer class would not. By modifying the SourceViewer class or otherwise write a new class, PageSourceFinder. The PageSourceFinder class should have one method with the signature public static String getsource (String s). This method should return the source code of the url given by String s. Write a new class called SourceTextGUI.java. Your new class should have a scrollable JTextArea and a JButton, and should use BorderLayout manager to place these components in the frame. Experiment with the size of the JFrame and the JTextArea until you are happy with the display. Add a JTextField to your program, and text to the JButton which says enter a url and then click me. Change your class so that this time the text that the user puts in the JTextField is treated as a url. If the url is parse-able then the source code of the page given by the url is printed in the JTextArea. If the text input by the user is not parse-able as a url then an error message is printed in the JTextArea. This error message should be generated in the PageSourceFinder class. [1 mark] [4 marks] [1 mark] [5 mark] [5 marks] [2 marks] [3 marks] [1 mark]

17 UNIVERSITY OF LONDON DIPLOMA AND BSc IN COMPUTING AND RELATED SUBJECTS FOR INTERNATIONAL PROGRAMMES STUDENTS COURSEWORK SUBMISSION FORM IMPORTANT, PLEASE NOTE: You must complete this form in full and attach it to the coursework that is to be submitted to the University. Full name:... (as it appears on your Registration Form) Student number:... Unit title:... Unit number:... Assignment number:... DECLARATION I declare that: I understand what is meant by plagiarism. I understand the implications of plagiarism. This assignment is all my own work and I have acknowledged any use of the published or unpublished works of other people. Signature Date

18 UNIVERSITY OF LONDON DIPLOMA AND BSc IN COMPUTING AND RELATED SUBJECTS FOR INTERNATIONAL PROGRAMMES STUDENTS COURSEWORK SUBMISSION CHECKLIST Before you submit your coursework to the University, have you: completed the title, unit number and assignment number on the submission form? signed and dated the Declaration? put your name and student number on every page? put the unit number, unit name and assignment number on every page? used more than one page? If so, have you securely stapled or tied the pages together? used a disk? If so, have you used a separate disk for each assignment? (Note: you should only use a disk if it is explicitly asked for in the assignment). labelled clearly and securely attached any disks? attached all parts of the coursework required (including the submission form)? If you fail to do these things your coursework may not be accepted. Please send all coursework to: The Registration and Learning Resources Office Room STG13 Stewart House University of London 32 Russell Square London WC1B 5DN United Kingdom Tel: +44 (0) Fax: +44 (0)