1. COS 260 DAY 23
Tony Gauvin

2. Agenda Mini Quiz 10 Assignment 7 Due Assignment 8 Posted
Questions?
Assignment 7 Due
Assignment 8 Posted
Dee Dec 12
Mini Quiz 10
Chapter 12
Password ElmerFudd
Capstone progress report 3 Due
Building Graphical User Interfaces Con’t

3. Capstone Project Capstone Project Description Fall 2017.pdf
October Proposal Due ed to Tony in Blackboard
October 27 Progress Report ed to Tony in Blackboard
November 17 Progress Report ed to Tony in Blackboard
November Progress Report ed to Tony in Blackboard
December All Deliverables & Presentation Due
Objects First with Java - A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling

4. Final CountDown Dec 1 Dec 5 Dec 8 Dec 12 @ 8 AM Gui’s Continued
Assignment 7 Due
Miniquiz 10
Course evaluations
Dec 5
Handling errors
Dec 8
Min quiz 11
Dec 8 AM
Assignment 8 due
Capstone Projects and presentation
Objects First with Java - A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling

5. Building Graphical User Interfaces
Objects First with Java
Building Graphical User Interfaces
Replace this with your course title and your name/contact details.
6.0
© David J. Barnes and Michael Kölling

6. Overview Constructing GUIs Interface components GUI layout
Event handling
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7. Dialogs Modal dialogs block all other interaction.
Forces a response from the user.
Non-modal dialogs allow other interaction.
This is sometimes desirable.
May be difficult to avoid inconsistencies.
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8. JOptionPane standard dialogs
Message dialog
Message text plus an OK button.
Confirm dialog
Yes, No, Cancel options.
Input dialog
Message text and an input field.
Variations are possible.
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9. A message dialog private void showAbout() {
JOptionPane.showMessageDialog(frame,
"ImageViewer\n" + VERSION,
"About ImageViewer",
JOptionPane.INFORMATION_MESSAGE); }
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10. Image filters Functions applied to the whole image.
int height = getHeight();
int width = getWidth();
for(int y = 0; y < height; y++) {
for(int x = 0; x < width; x++) {
Color pixel = getPixel(x, y);
alter the pixel's color value;
setPixel(x, y, pixel); }
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11. Adding further filters
private void makeLighter() {
if(currentImage != null) {
currentImage.lighter();
frame.repaint();
showStatus("Applied: lighter"); }
else {
showStatus("No image loaded.");
Code duplication?
Refactor!
private void threshold() {
if(currentImage != null) {
currentImage.threshold();
frame.repaint();
showStatus("Applied: threshold"); }
else {
showStatus("No image loaded.");
© 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

12. Adding further filters
Define a Filter superclass (abstract).
Create function-specific subclasses.
Create a collection of subclass instances in ImageViewer.
Define a generic applyFilter method.
See imageviewer2-0.
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13. imageviewer2-0
Ex 13.38
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14. Buttons and nested layouts
A GridLayout inside
a FlowLayout inside
a BorderLayout.
Ex 13.45
13.46 , , 13.48
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15. Borders Used to add decoration around components.
Defined in javax.swing.border
BevelBorder, CompoundBorder, EmptyBorder, EtchedBorder, TitledBorder.
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16. Adding spacing JPanel contentPane = (JPanel)frame.getContentPane();
contentPane.setBorder(new EmptyBorder(6, 6, 6, 6));
// Specify the layout manager with nice spacing
contentPane.setLayout(new BorderLayout(6, 6));
imagePanel = new ImagePanel();
imagePanel.setBorder(new EtchedBorder());
contentPane.add(imagePanel, BorderLayout.CENTER);
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17. Other components Slider
Spinner
Tabbed pane
Scroll pane
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18. Nested class syntax Class definitions may be nested.
public class Enclosing { … private class Inner { … } }
This is tight coupling
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19. Inner classes
Instances of the inner class are localized within the enclosing class.
Instances of the inner class have access to the private members of the enclosing class.
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20. Anonymous inner classes
Obey the rules of inner classes.
Used to create one-off objects for which a class name is not required.
Use a special syntax.
The instance is always referenced via its supertype, as it has no subtype name.
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21. Anonymous action listener
JMenuItem openItem = new JMenuItem("Open");
openItem.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
openFile(); }
});
Compare with the lambda version
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22. Lambda for ActionListener
JMenuItem openItem = new JMenuItem("Open");
...
openItem.addActionListener(
(ActionEvent ev) -> { openFile(); } );
General form
item.addActionListener(ev -> { actions });
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23. Why use inner classes?
The Lambda notations only works with functional interface (one abstract message)
Most listener(s) have more than one interface
Sometime we use adapters instead of listeners
Objects First with Java - A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling

24. Anonymous class elements
Anonymous object creation
openItem.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e)
openFile(); } );
Class definition
Actual parameter
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25. Exit on window close
frame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } });
WindowAdapter provides a no-op implementation of the WindowListener interface.
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26. Review Aim for cohesive application structures.
Endeavor to keep GUI elements separate from application functionality.
Pre-defined components simplify creation of sophisticated GUIs.
Layout managers handle component juxtaposition.
Nest containers for further control.
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27. Review Many components recognize user interactions with them.
Reactive components deliver events to listeners.
Lambdas are commonly used to implement listeners.
Anonymous inner classes are used where lambdas are not possible.
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