COS 260 DAY 23 Tony Gauvin

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

Capstone Project Capstone Project Description Fall 2017.pdf October 2 Proposal Due E-mailed to Tony in Blackboard October 27 Progress Report E-mailed to Tony in Blackboard November 17 Progress Report E-mailed to Tony in Blackboard November 30 Progress Report E-mailed to Tony in Blackboard December 12@8AM All Deliverables & Presentation Due Objects First with Java - A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling

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 12 @ 8 AM Assignment 8 due Capstone Projects and presentation Objects First with Java - A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling

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

Overview Constructing GUIs Interface components GUI layout Event handling © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

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. © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

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. https://docs.oracle.com/javase/8/docs/api/javax/swing/JOptionPane.html https://docs.oracle.com/javase/tutorial/uiswing/components/dialog.html © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

A message dialog private void showAbout() { JOptionPane.showMessageDialog(frame, "ImageViewer\n" + VERSION, "About ImageViewer", JOptionPane.INFORMATION_MESSAGE); } © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

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); } © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

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.

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. © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

imageviewer2-0 Ex 13.38 © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Buttons and nested layouts A GridLayout inside a FlowLayout inside a BorderLayout. Ex 13.45 13.46 , 13.47 , 13.48 © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Borders Used to add decoration around components. Defined in javax.swing.border BevelBorder, CompoundBorder, EmptyBorder, EtchedBorder, TitledBorder. https://docs.oracle.com/javase/tutorial/uiswing/components/border.html © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

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); © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Other components Slider https://docs.oracle.com/javase/tutorial/uiswing/components/slider.html Spinner https://docs.oracle.com/javase/tutorial/uiswing/components/spinner.html Tabbed pane https://docs.oracle.com/javase/tutorial/uiswing/components/tabbedpane.html Scroll pane https://docs.oracle.com/javase/tutorial/uiswing/components/scrollpane.html © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Nested class syntax Class definitions may be nested. public class Enclosing { … private class Inner { … } } This is tight coupling © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

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. © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

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. © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Anonymous action listener JMenuItem openItem = new JMenuItem("Open"); openItem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { openFile(); } }); Compare with the lambda version © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Lambda for ActionListener JMenuItem openItem = new JMenuItem("Open"); ... openItem.addActionListener( (ActionEvent ev) -> { openFile(); } ); General form item.addActionListener(ev -> { actions }); © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

Why use inner classes? The Lambda notations only works with functional interface (one abstract message) Most listener(s) have more than one interface https://docs.oracle.com/javase/8/docs/api/java/awt/event/MouseListener.html https://docs.oracle.com/javase/7/docs/api/java/awt/event/MouseMotionListener.html Sometime we use adapters instead of listeners https://www.youtube.com/watch?v=UuKNGMCfSkQ https://docs.oracle.com/javase/8/docs/api/java/awt/event/WindowAdapter.html Objects First with Java - A Practical Introduction using BlueJ, © David J. Barnes, Michael Kölling

Anonymous class elements Anonymous object creation openItem.addActionListener( new ActionListener() { public void actionPerformed(ActionEvent e) openFile(); } ); Class definition Actual parameter © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

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. © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

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. © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.

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. © 2017 Pearson Education, Inc. Hoboken, NJ. All rights reserved.