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Lecture 11

Lecture 11. CS 202 Fall 2013. ActionEvent Methods. ActionEvent contains many methods you can use to get information about events. import java.awt.BorderLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.Date; import javax.swing.JButton;

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Lecture 11

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  1. Lecture 11 CS 202 Fall 2013

  2. ActionEvent Methods ActionEvent contains many methods you can use to get information about events. import java.awt.BorderLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.Date; import javax.swing.JButton; import javax.swing.JFrame; public class EventInfoGUI { JFrame frame; JButton button; private void createAndShowGUI() { frame = new JFrame("Event Info Demo"); button = new JButton("Click Me"); frame.add(button, BorderLayout.CENTER); button.addActionListener(new ActionListener(){ @Override public void actionPerformed(ActionEvent event) { System.out.println("Command: " + event.getActionCommand()); System.out.println("ID: " + event.getID()); System.out.println("Modifiers: " + event.getModifiers()); System.out.println("Source: " + event.getSource()); System.out.println("Date and Time: " + new Date(event.getWhen())); System.out.println("Parameter String: " + event.paramString()); System.out.println("Class: " + event.getClass()); }}); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.pack(); frame.setVisible(true); } public static void main(String[] args) { EventInfoGUI gui = new EventInfoGUI(); gui.createAndShowGUI(); }; } See http://docs.oracle.com/javase/6/docs/api/java/awt/event/ActionEvent.html for a complete list

  3. ActionEvent Methods package guidemo; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; public class SquareGrid { JFrame theFrame; JButton[][] buttons; int rowCount = 5; int colCount = 5; JPanel panel; private void createAndShowGui(){ theFrame = new JFrame ("grid"); buttons = new JButton[rowCount][colCount]; panel = new JPanel(); panel.setLayout(new GridLayout(rowCount, colCount)); for(int rowCounter = 0; rowCounter < rowCount; rowCounter++) for(int colCounter = 0; colCounter < colCount; colCounter++){ final JButton j = new JButton("not clicked"); j.addActionListener(new ActionListener(){ boolean clicked = false; @Override public void actionPerformed(ActionEvent event) { if(clicked == false) clicked = true; else clicked = false; if(clicked) j.setText("clicked"); else j.setText("not clicked"); } }); buttons[rowCounter][colCounter] = j; panel.add(j); } theFrame.add(panel); theFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); theFrame.pack(); theFrame.setVisible(true); } public static void main(String[] args){ SquareGrid h = new SquareGrid(); h.createAndShowGui(); } }

  4. ActionEvent Methods for(int rowCounter = 0; rowCounter < rowCount; rowCounter++) for(int colCounter = 0; colCounter < colCount; colCounter++){ final JButton j = new JButton("Click Me!"); j.setBackground(Color.RED); j.addActionListener(new ActionListener(){ boolean clicked = false; @Override public void actionPerformed(ActionEvent event) { if(clicked == false) clicked = true; else clicked = false; if(clicked) j.setBackground(Color.GREEN); else j.setBackground(Color.RED); System.out.println("Source: " + event.getSource()); } }); buttons[rowCounter][colCounter] = j; panel.add(j); } To make a component accessible inside an anonymous ActionListener attached to it, make the component final

  5. Listener Classes • Recall the code from the Celsius Converter, which used an anonymous class to implement ActionListener • This is a convenient solution if the listener is simple and you only need to use it in one place • However, it is hard to read and can’t be reused • For more complex ActionListeners, it is better to code non-anonymous classes that implement ActionListener, either separately or as inner classes

  6. Listener Classes • EventInfoGUI2 with separate ClickListener class import java.awt.BorderLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.Date; import javax.swing.JButton; import javax.swing.JFrame; public class EventInfoGUI2 { JFrame frame; JButton button; private void createAndShowGUI() { frame = new JFrame("Event Info Demo"); button = new JButton("Click Me"); frame.add(button, BorderLayout.CENTER); button.addActionListener(new EventInfoClickListener()); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.pack(); frame.setVisible(true); } public static void main(String[] args) { EventInfoGUI2 gui = new EventInfoGUI2(); gui.createAndShowGUI(); }; }

  7. Listener Classes • ClickListener class import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.Date; public class EventInfoClickListener implements ActionListener{ @Override public void actionPerformed(ActionEvent event) { System.out.println("Command: " + event.getActionCommand()); System.out.println("ID: " + event.getID()); System.out.println("Modifiers: " + event.getModifiers()); System.out.println("Source: " + event.getSource()); System.out.println("Date and Time: " + new Date(event.getWhen())); System.out.println("Parameter String: " + event.paramString()); System.out.println("Class: " + event.getClass()); } }

  8. Listener Classes • It is also common to use an inner class that implements a Listener interface: import java.awt.BorderLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.Date; import javax.swing.JButton; import javax.swing.JFrame; public class EventInfoGUI3 { JFrame frame; JButton button; private void createAndShowGUI() { frame = new JFrame("Event Info Demo"); button = new JButton("Click Me"); frame.add(button, BorderLayout.CENTER); button.addActionListener(new EventInfoClickListener2()); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.pack(); frame.setVisible(true); } public static void main(String[] args) { EventInfoGUI3 gui = new EventInfoGUI3(); gui.createAndShowGUI(); }; private class EventInfoClickListener2 implements ActionListener{ @Override public void actionPerformed(ActionEvent event) { System.out.println("Command: " + event.getActionCommand()); System.out.println("ID: " + event.getID()); System.out.println("Modifiers: " + event.getModifiers()); System.out.println("Source: " + event.getSource()); System.out.println("Date and Time: " + new Date(event.getWhen())); System.out.println("Parameter String: " + event.paramString()); System.out.println("Class: " + event.getClass()); } } }

  9. JTable • JTable is a JComponent that displays a table • Contents come from a Table Model • The most straightforward form of Table Model uses a one-dimensional array of Strings for column names and a two-dimensional array of Objects for data. • This can be invisible to the programmer, who just sends the parameters to the JTable constructor • Since your data is usually in a list, not a two dimensional array, you have to write a method to generate the array. • There are ways to provide more sophisticated data models for JTable, but they are *very complicated*

  10. JTable // http://docs.oracle.com/javase/tutorial/uiswing/examples/components/SimpleTableDemoProject/src/components/SimpleTableDemo.java package menudemo; import java.awt.Dimension; import java.awt.GridLayout; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTable; public class SimpleTableDemo extends JPanel { public SimpleTableDemo() { super(new GridLayout(1, 0)); String[] columnNames = { "First Name", "Last Name", "Sport", "# of Years", "Vegetarian" }; final Object[][] data = { { "Kathy", "Smith", "Snowboarding", new Integer(5), new Boolean(false) }, { "John", "Doe", "Rowing", new Integer(3), new Boolean(true) }, { "Sue", "Black", "Knitting", new Integer(2), new Boolean(false) }, { "Jane", "White", "Speed reading", new Integer(20), new Boolean(true) }, { "Joe", "Brown", "Pool", new Integer(10), new Boolean(false) } }; JTable table = setUpTable(data, columnNames); // Create the scroll pane and add the table to it. JScrollPanescrollPane = new JScrollPane(table); // Add the scroll pane to this panel. add(scrollPane); } private JTablesetUpTable(Object[][] data, String[] columnNames){ JTable table = new JTable(data, columnNames); table.setPreferredScrollableViewportSize(new Dimension(500, 70)); table.setFillsViewportHeight(true); table.setAutoCreateRowSorter(true); return table; } private static void createAndShowGUI() { // Create and set up the window. JFrame frame = new JFrame("SimpleTableDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // Create and set up the content pane. SimpleTableDemonewContentPane = new SimpleTableDemo(); newContentPane.setOpaque(true); // content panes must be opaque frame.setContentPane(newContentPane); // Display the window. frame.pack(); frame.setVisible(true); } public static void main(String[] args) { createAndShowGUI(); } }

  11. Menus • JMenus are placed in JMenuBarsand contain JMenuItems • JMenuItems trigger events that can be handled with ActionListeners • setMnemonic() provides hotkeys as an alternative to using the mouse; very useful for accessibility.

  12. // http://zetcode.com/tutorials/javaswingtutorial/menusandtoolbars/ package menudemo; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyEvent; import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.SwingUtilities; public class Example extends JFrame { public Example() { initUI(); } public final void initUI() { JMenuBar menubar = new JMenuBar(); JMenu file = new JMenu("File"); file.setMnemonic(KeyEvent.VK_F); JMenuItem eMenuItem = new JMenuItem("Exit"); eMenuItem.setMnemonic(KeyEvent.VK_E); eMenuItem.setToolTipText("Exit application"); eMenuItem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { System.exit(0); } }); file.add(eMenuItem); menubar.add(file); setJMenuBar(menubar); setTitle("Simple menu"); setSize(300, 200); setLocationRelativeTo(null); setDefaultCloseOperation(EXIT_ON_CLOSE); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { Example ex = new Example(); ex.setVisible(true); } }); } }

  13. JFileChooser • JFileChooser is a dialog box that lets the user choose a file to open, save as , etc. It will look familiar when you see it. • By default, JFileChooser starts in the users' default directory (the one you see if you open Windows Explorer). Other starting directories can be specified. • JFileChooser returns a selected file or an array of selected files • JFileChooser() creates JFileChooser instance using user’s default directory. • JFileChooser(File currentDirectory) creates JFileChooser instance using a given directory. • setMultiSelectionEnabled(true) allows multiple file selections. This may or may not be appropriate for your task.

  14. Example • Example allows user to choose one or more files, using a method from a separate FileDumper class to print the contents of the files(s) to output. • Test it with text files only, or you will get strange results

  15. package menudemo; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyEvent; import java.io.File; import javax.swing.JFileChooser; import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; public class JFileChooserDemo { final JFrame frame; final FileDumper f; public JFileChooserDemo() { f = new FileDumper(); frame = new JFrame("JFileChooser Demo"); initUI(); } public final void initUI() { JMenuBar menubar = setUpMenus(); setUpFrame(menubar); }

  16. public JMenuBar setUpMenus() { JMenuBar menubar = new JMenuBar(); JMenu file = new JMenu("File"); file.setMnemonic(KeyEvent.VK_F); // instance variables are only visible inside anonymous classes if they // are final final JFileChooser fc = new JFileChooser(); // allow multiple selections. Don't use with Save As... ! fc.setMultiSelectionEnabled(true); JMenuItem fMenuItem = new JMenuItem("Open"); fMenuItem.setMnemonic(KeyEvent.VK_O); fMenuItem.setToolTipText("Open A File"); fMenuItem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { int retVal = fc.showOpenDialog(frame); if (retVal == JFileChooser.APPROVE_OPTION) { File[] selectedfiles = fc.getSelectedFiles(); for (int i = 0; i < selectedfiles.length; i++) { f.readFileToSystemOut(selectedfiles[i]); } } } }); JMenuItem eMenuItem = new JMenuItem("Exit"); eMenuItem.setMnemonic(KeyEvent.VK_E); eMenuItem.setToolTipText("Exit application"); eMenuItem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { System.exit(0); } }); file.add(fMenuItem); file.add(eMenuItem); menubar.add(file); return menubar; }

  17. private void setUpFrame(JMenuBar menubar) { frame.setJMenuBar(menubar); frame.setTitle("Simple menu"); frame.setSize(300, 200); frame.setLocationRelativeTo(null); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } public static void main(String[] args) { JFileChooserDemo ex = new JFileChooserDemo(); } }

  18. FileDumper package menudemo; import java.io.File; import java.io.FileNotFoundException; import java.util.Scanner; public class FileDumper { public void readFileToSystemOut(File f){ Scanner reader; try { System.out.println(f.getName()); reader = new Scanner(f); //... Loop as long as there are input lines. String line = null; while (reader.hasNextLine()) { line = reader.nextLine(); System.out.println(line); } //... Close reader reader.close(); System.out.println(); } catch (FileNotFoundException e) { e.printStackTrace(); } } }

  19. Look And Feel • Swing apps, like those using many other GUI frameworks, can use a variety of "Look and Feel" styles that control various graphic aspects of the GUI. • Available L and Fs vary between platforms • Set L and F in the first line of main: • UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");

  20. Look And Feel package guidemo; // from java2s: http://www.java2s.com/Code/Java/Swing-JFC/SimplelookandfeelExample.htm import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.swing.ButtonGroup; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JRadioButton; import javax.swing.SwingUtilities; import javax.swing.UIManager; public class SimpleLookAndFeelDemo extends JPanel { static JFrame frame; static String metal = "Metal"; static String metalClassName = "javax.swing.plaf.metal.MetalLookAndFeel"; static String motif = "Motif"; static String motifClassName = "com.sun.java.swing.plaf.motif.MotifLookAndFeel";

  21. Look And Feel static String windows = "Windows"; static String windowsClassName = "com.sun.java.swing.plaf.windows.WindowsLookAndFeel"; JRadioButton metalButton, motifButton, windowsButton; public SimpleLookAndFeelDemo() { JButton button = new JButton("Hello, world"); button.setMnemonic('h'); // for looks only; button does nada metalButton = new JRadioButton(metal); metalButton.setMnemonic('o'); metalButton.setActionCommand(metalClassName); motifButton = new JRadioButton(motif); motifButton.setMnemonic('m'); motifButton.setActionCommand(motifClassName); windowsButton = new JRadioButton(windows); windowsButton.setMnemonic('w'); windowsButton.setActionCommand(windowsClassName); ButtonGroup group = new ButtonGroup(); group.add(metalButton); group.add(motifButton); group.add(windowsButton);

  22. Look And Feel RadioListener myListener = new RadioListener(); metalButton.addActionListener(myListener); motifButton.addActionListener(myListener); windowsButton.addActionListener(myListener); add(button); add(metalButton); add(motifButton); add(windowsButton); } class RadioListener implements ActionListener { public void actionPerformed(ActionEvent e) { String lnfName = e.getActionCommand(); try { UIManager.setLookAndFeel(lnfName); SwingUtilities.updateComponentTreeUI(frame); frame.pack(); } catch (Exception exc) { JRadioButton button = (JRadioButton) e.getSource(); button.setEnabled(false); updateState(); System.err.println("Could not load LookAndFeel: " + lnfName); } } }

  23. Look And Feel public void updateState() { String lnfName = UIManager.getLookAndFeel().getClass().getName(); if (lnfName.indexOf(metal) >= 0) { metalButton.setSelected(true); } else if (lnfName.indexOf(windows) >= 0) { windowsButton.setSelected(true); } else if (lnfName.indexOf(motif) >= 0) { motifButton.setSelected(true); } else { System.err.println("SimpleExample is using an unknown L&F: " + lnfName); } } public static void main(String s[]) { SimpleLookAndFeelDemo panel = new SimpleLookAndFeelDemo(); frame = new JFrame("SimpleExample"); frame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); frame.getContentPane().add("Center", panel); frame.pack(); frame.setVisible(true); panel.updateState(); } }

  24. More On Layout Managers • Border Layout can also be used with these areas: • PAGE_START • PAGE_END • LINE_START • LINE_END • CENTER • It is easy to think of them as corresponding to North, South, West, East, and Center on a map.

  25. Instanceof • The next layout manager demo uses Java's instanceof operator, which determines whether an object is an instance of a particular class • The syntax of instanceof may be counterintuitive; the keyword does not use camel case and there are no parentheses around the class name • The next slide shows a simple demo of instanceof

  26. Instanceof package demos; public class Demo { Object myObject; public void setMyObject(Object o) { myObject = o; } public Object getMyObject() { return myObject; } public static void main(String[] args) { Demo demo = new Demo(); String newObject = new String("John"); demo.setMyObject(newObject); Object o = demo.getMyObject(); if (o instanceof String) System.out.println("\"" + o + "\"" + " is a String!"); else System.out.println("not a String!"); Object arch = new Archimedes(); demo.setMyObject(arch); Object o2 = demo.getMyObject(); if (o2 instanceof String) System.out.println("\"" + 02 + "\"" + " is a String!"); else System.out.println(o2 + " is not a String!"); } }

  27. More On Layout Managers package menudemo; // http://docs.oracle.com/javase/tutorial/uiswing/examples/layout/BorderLayoutDemoProject/src/layout/BorderLayoutDemo.java import javax.swing.*; import java.awt.BorderLayout; import java.awt.Container; import java.awt.Dimension; public class BorderLayoutDemo { public static booleanRIGHT_TO_LEFT = false; public static void addComponentsToPane(Container pane) { if (!(pane.getLayout() instanceofBorderLayout)) { pane.add(new JLabel("Container doesn't use BorderLayout!")); return; } if (RIGHT_TO_LEFT) { pane.setComponentOrientation( java.awt.ComponentOrientation.RIGHT_TO_LEFT); } JButton button = new JButton("Button 1 (PAGE_START)"); pane.add(button, BorderLayout.PAGE_START); //Make the center component big, since that's the //typical usage of BorderLayout. button = new JButton("Button 2 (CENTER)"); button.setPreferredSize(new Dimension(200, 100)); pane.add(button, BorderLayout.CENTER);

  28. More On Layout Managers button = new JButton("Button 3 (LINE_START)"); pane.add(button, BorderLayout.LINE_START); button = new JButton("Long-Named Button 4 (PAGE_END)"); pane.add(button, BorderLayout.PAGE_END); button = new JButton("5 (LINE_END)"); pane.add(button, BorderLayout.LINE_END); } private static void createAndShowGUI() { //Create and set up the window. JFrame frame = new JFrame("BorderLayoutDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Set up the content pane. addComponentsToPane(frame.getContentPane()); //Use the content pane's default BorderLayout. No need for //setLayout(new BorderLayout()); //Display the window. frame.pack(); frame.setVisible(true); }

  29. More On Layout Managers public static void main(String[] args) { /* Use an appropriate Look and Feel */ try { //UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel"); } catch (UnsupportedLookAndFeelException ex) { ex.printStackTrace(); } catch (IllegalAccessException ex) { ex.printStackTrace(); } catch (InstantiationException ex) { ex.printStackTrace(); } catch (ClassNotFoundException ex) { ex.printStackTrace(); } /* Turn off metal's use bold fonts */ UIManager.put("swing.boldMetal", Boolean.FALSE); //Schedule a job for the event dispatch thread: //creating and showing this application's GUI. javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } }

  30. More On Layout Managers • The CardLayout class manages two or more components (usually JPanel instances) that share the same display space. • When using the CardLayout class, let the user choose between the components by using a combo box, menu, etc. http://docs.oracle.com/javase/tutorial/uiswing/layout/card.html

  31. More On Layout Managers package menudemo; // http://docs.oracle.com/javase/tutorial/uiswing/examples/layout/CardLayoutDemoProject/src/layout/CardLayoutDemo.java import java.awt.*; import java.awt.event.*; import javax.swing.*; public class CardLayoutDemo implements ItemListener { JPanel cards; //a panel that uses CardLayout final static String BUTTONPANEL = "Card with JButtons"; final static String TEXTPANEL = "Card with JTextField"; public void addComponentToPane(Container pane) { //Put the JComboBox in a JPanel to get a nicer look. JPanel comboBoxPane = new JPanel(); //use FlowLayout String comboBoxItems[] = { BUTTONPANEL, TEXTPANEL }; JComboBox cb = new JComboBox(comboBoxItems); cb.setEditable(false); cb.addItemListener(this); comboBoxPane.add(cb);

  32. More On Layout Managers //Create the "cards". JPanel card1 = new JPanel(); card1.add(new JButton("Button 1")); card1.add(new JButton("Button 2")); card1.add(new JButton("Button 3")); JPanel card2 = new JPanel(); card2.add(new JTextField("TextField", 20)); //Create the panel that contains the "cards". cards = new JPanel(new CardLayout()); cards.add(card1, BUTTONPANEL); cards.add(card2, TEXTPANEL); pane.add(comboBoxPane, BorderLayout.PAGE_START); pane.add(cards, BorderLayout.CENTER); } public void itemStateChanged(ItemEvent evt) { CardLayout cl = (CardLayout)(cards.getLayout()); System.out.println(evt.getItem()); System.out.println(evt.getSource()); cl.show(cards, (String)evt.getItem()); }

  33. More On Layout Managers private static void createAndShowGUI() { //Create and set up the window. JFrame frame = new JFrame("CardLayoutDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Create and set up the content pane. CardLayoutDemo demo = new CardLayoutDemo(); demo.addComponentToPane(frame.getContentPane()); //Display the window. frame.pack(); frame.setVisible(true); }

  34. More On Layout Managers public static void main(String[] args) { /* Use an appropriate Look and Feel */ try { //UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel"); } catch (UnsupportedLookAndFeelException ex) { ex.printStackTrace(); } catch (IllegalAccessException ex) { ex.printStackTrace(); } catch (InstantiationException ex) { ex.printStackTrace(); } catch (ClassNotFoundException ex) { ex.printStackTrace(); } /* Turn off metal's use of bold fonts */ UIManager.put("swing.boldMetal", Boolean.FALSE); createAndShowGUI(); } }

  35. Images in Swing • BufferedImage reads and writes image files • ImageIcon displays an image. It was originally used to create icons but is typically used for all images. • ImageIcons are typically added to Jlabels which are then placed in the frame

  36. // adapted from http://stackoverflow.com/questions/299495/java-swing-how-to-add-an-image-to-a-jpanel // paste the image file directly to your project, not into src or any other folder within it package menudemo; import java.awt.BorderLayout; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import javax.imageio.ImageIO; import javax.swing.ImageIcon; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; public class ImageDemo { JFrame frame; JPanel panel; JLabel picLabel; BufferedImage myPicture; public ImageDemo() { frame = new JFrame(); myPicture = null; try { File f = new File("godzilla.jpg"); myPicture = ImageIO.read(f); ImageIcon i = new ImageIcon(myPicture); picLabel = new JLabel(i); } catch (IOException e) { e.printStackTrace(); } setUpFrame(); } private void setUpFrame(){ frame = new JFrame("Show an image"); panel = new JPanel(); panel.add(picLabel); frame.getContentPane().add(panel, BorderLayout.CENTER); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.pack(); frame.setVisible(true); } public static void main(String[] args) { ImageDemo i = new ImageDemo(); } }

  37. Images More sophisticated image demo, from http://alvinalexander.com/java/jwarehouse/netbeans-src/usersguide/demosrc/examples/imageviewer/ImageFrame.java.shtml The author of this demo used a GUI builder which left some annotations that are not relevant to us. I may not have deleted them all.

  38. Images This example uses several new (to us) components. Note that if you mouse-hover over a class name in code in Eclipse, you see a description of the class from the class' Javadoc.

  39. Images package week10; /** This class is an entry point of the simple image viewer. * It creates and shows the main application frame. */ public class ImageViewer extends javax.swing.JFrame { /** Image Viewer constructor. * It initializes all GUI components [menu bar, menu items, desktop pane, etc.]. */ public ImageViewer() { initComponents(); pack(); setBounds( 100, 100, 400, 400 ); } private void initComponents() { desktop = new javax.swing.JDesktopPane(); mainMenuBar = new javax.swing.JMenuBar(); fileMenu = new javax.swing.JMenu(); openMenuItem = new javax.swing.JMenuItem(); jSeparator1 = new javax.swing.JSeparator(); exitMenuItem = new javax.swing.JMenuItem(); setTitle("Image Viewer"); addWindowListener(new java.awt.event.WindowAdapter() { public void windowClosing(java.awt.event.WindowEvent evt) { exitForm(evt); } });

  40. Images getAccessibleContext().setAccessibleName("Image Viewer Frame"); getContentPane().add(desktop, java.awt.BorderLayout.CENTER); desktop.getAccessibleContext().setAccessibleName("Image Desktop"); desktop.getAccessibleContext().setAccessibleDescription("Image desktop"); fileMenu.setMnemonic('f'); fileMenu.setText("File"); openMenuItem.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_O, java.awt.event.InputEvent.CTRL_MASK)); openMenuItem.setMnemonic('o'); openMenuItem.setText("Open"); openMenuItem.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { openMenuItemActionPerformed(evt); } }); fileMenu.add(openMenuItem); openMenuItem.getAccessibleContext().setAccessibleName("Open Menu Item"); openMenuItem.getAccessibleContext().setAccessibleDescription("Open menu item."); fileMenu.add(jSeparator1); exitMenuItem.setMnemonic('x'); exitMenuItem.setText("Exit"); exitMenuItem.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { exitMenuItemActionPerformed(evt); } });

  41. Images fileMenu.add(exitMenuItem); exitMenuItem.getAccessibleContext().setAccessibleName("Exit Menu Item"); exitMenuItem.getAccessibleContext().setAccessibleDescription("Exit menu item."); mainMenuBar.add(fileMenu); fileMenu.getAccessibleContext().setAccessibleName("File Menu"); fileMenu.getAccessibleContext().setAccessibleDescription("File menu."); setJMenuBar(mainMenuBar); mainMenuBar.getAccessibleContext().setAccessibleName("Main Menu Bar"); mainMenuBar.getAccessibleContext().setAccessibleDescription("Main menu bar."); } /** This method is called when File -> Exit menu item is invoked. * It closes the application. * @param evt ActionEvent instance passed from actionPerformed event. */ private void exitMenuItemActionPerformed(java.awt.event.ActionEvent evt) { System.exit( 0 ); } /** This method is called when File -> Open menu item is invoked. * It displays a dialog to choose the image file to be opened and displayed. * @param evt ActionEvent instance passed from actionPerformed event. */

  42. Images private void openMenuItemActionPerformed(java.awt.event.ActionEventevt) { javax.swing.JFileChooser chooser = new javax.swing.JFileChooser(); chooser.addChoosableFileFilter(new ImageFileFilter()); int option = chooser.showOpenDialog(this); if (option == javax.swing.JFileChooser.APPROVE_OPTION) { java.io.File file = chooser.getSelectedFile(); if (file == null) return; ImageFrameifr = new ImageFrame(file.getAbsolutePath()); desktop.add(ifr, javax.swing.JLayeredPane.DEFAULT_LAYER); ifr.setVisible( true ); ifr.setSize(200, 200); ifr.setLocation(0, 0); } } /** This method is called when the application frame is closed. * @paramevtWindowEvent instance passed from windowClosing event. */ private void exitForm(java.awt.event.WindowEventevt) { System.exit(0); } /** Define custom file filter for acceptable image files. */ private static class ImageFileFilter extends javax.swing.filechooser.FileFilter { public boolean accept(java.io.File file) { if (file == null) return false; return file.isDirectory() || file.getName().toLowerCase().endsWith(".gif") || file.getName().toLowerCase().endsWith(".jpg"); } public String getDescription() { return "Image files (*.gif, *.jpg)"; } } // Variables declaration - do not modify//GEN-BEGIN:variables private javax.swing.JDesktopPane desktop; private javax.swing.JMenuItemexitMenuItem; private javax.swing.JMenufileMenu; private javax.swing.JSeparator jSeparator1; private javax.swing.JMenuBarmainMenuBar; private javax.swing.JMenuItemopenMenuItem; // End of variables declaration//GEN-END:variables /** Starts the application. * @paramargs Application arguments. */ public static void main(String args[]) { new ImageViewer().show(); } }

  43. Images public String getDescription() { return "Image files (*.gif, *.jpg)"; } } // Variables declaration private javax.swing.JDesktopPane desktop; private javax.swing.JMenuItemexitMenuItem; private javax.swing.JMenufileMenu; private javax.swing.JSeparator jSeparator1; private javax.swing.JMenuBarmainMenuBar; private javax.swing.JMenuItemopenMenuItem; // End of variables declaration//GEN-END:variables /** Starts the application. * @paramargs Application arguments. */ public static void main(String args[]) { new ImageViewer().show(); } }

  44. package week10; /** Instances of this class create internal frames to display given images. */ public class ImageFrame extends javax.swing.JInternalFrame { /** ImageFrame constructor. * It creates new internal frame containing the given image and displays it. */ public ImageFrame(String imageName ) { initComponents(); setTitle(imageName); imageLabel.setIcon(new javax.swing.ImageIcon(imageName) ); } /** This method is called from within the constructor to * initialize the form. */ private void initComponents() { jScrollPane1 = new javax.swing.JScrollPane(); imageLabel = new javax.swing.JLabel(); setClosable(true); setIconifiable(true); setResizable(true); getAccessibleContext().setAccessibleName("Image Internal Frame"); getAccessibleContext().setAccessibleDescription("Image internal frame."); jScrollPane1.setViewportView(imageLabel); imageLabel.getAccessibleContext().setAccessibleName("Image Label"); imageLabel.getAccessibleContext().setAccessibleDescription("Image label."); getContentPane().add(jScrollPane1, java.awt.BorderLayout.CENTER); } // Variables declaration private javax.swing.JLabel imageLabel; private javax.swing.JScrollPane jScrollPane1; }

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