Java Programming: Creating a GUI with JFC/Swing

1. Java Programming: Creating a GUI with JFC/Swing Vyacheslav Grebenyuk CTDE, AI dept., KhNURE

2. Content • About the JFC and Swing • Learning Swing by Example (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

3. About the JFC and Swing • JFC is short for Java Foundation Classes, which encompass a group of features for building graphical user interfaces (GUIs) and adding rich graphics functionality and interactivity to Java applications (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

4. Features of the Java Foundation Classes 1 (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

5. Features of the Java Foundation Classes 2 (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

6. Which Releases Contain the Swing API? • The short answer is that the Swing API has been included in the Java 2 platform, Standard Edition (J2SETM) since its initial release (1.2) (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

7. Swing API Content • In release 1.4 of the Java platform, the Swing API has 17 public packages: • javax.accessibilityjavax.swing.plafjavax.swing.text.html • javax.swingjavax.swing.plaf.basicjavax.swing.text.parser • javax.swing.borderjavax.swing.plaf.metaljavax.swing.text.rtf • javax.swing.text javax.swing.plaf.multijavax.swing.tree • javax.swing.eventjavax.swing.tablejavax.swing.undo • javax.swing.filechooserjavax.swing.colorchooser • Fortunately, most programs use only a small subset of the API • javax.swing javax.swing.event (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

8. Example One: Your First Swing Program import javax.swing.*; public class HelloWorldSwing { private static void createAndShowGUI() { //Make sure we have nice window decorations. JFrame.setDefaultLookAndFeelDecorated(true); //Create and set up the window. JFrame frame = new JFrame("HelloWorldSwing"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Add the ubiquitous "Hello World" label. JLabel label = new JLabel("Hello World"); frame.getContentPane().add(label); //Display the window. frame.pack(); frame.setVisible(true); } (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

9. Example One: Your First Swing Program 2 public static void main(String[] args) { //Schedule a job for the event-dispatching thread: //creating and showing this application's GUI. javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } } (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

10. The basic code in every Swing program • Import the pertinent packages • Set up a top-level container • Display the container • Be thread-safe (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

11. Imports • import javax.swing.*; • import java.awt.*; • import java.awt.event.*; • Swing components use the AWT infrastructure, including the AWT event model (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

12. Top-level Swing container • Every program with a Swing GUI must have at least one top-level Swing container • A top-level Swing container provides the support Swing components need for painting and event handling • There are three commonly used top-level Swing containers: JFrame, JDialog, and (for applets) JApplet (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

13. JComponent • With the exception of top-level containers, such as JFrame, all Swing components descend from the JComponent class • HelloWorldSwing uses a JComponent descendant called JLabel, which displays the text Hello World JLabel label = new JLabel("Hello World"); frame.getContentPane().add(label); (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

14. Add components • Note that the label is added to the frame’s content pane instead of to the frame itself. Every top-level container has a content pane that contains, directly or indirectly, all the visible components (except for menus and window decorations) in the top-level container (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

15. Program exit • To make the program exit when the Close button is clicked, we include this code: frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); • In older programs frame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

16. Look and Feel • The following screenshots show the GUI of the SwingApplication, each one with a different look and feel String lookAndFeel = null; ... lookAndFeel = UIManager.getCrossPlatformLookAndFeelClassName(); ... try { UIManager.setLookAndFeel(lookAndFeel); } catch (Exception e) { } ...// Create and show the GUI... (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

17. Setting Up Buttons and Labels • the code that initializes the button: JButton button = new JButton("I'm a Swing button!"); button.setMnemonic('i'); button.addActionListener(/*...create an action listener...*/); • the code that initializes and manipulates the label: private static String labelPrefix = "Number of button clicks: "; private int numClicks = 0; final JLabel label = new JLabel(labelPrefix + "0 "); label.setLabelFor(button); label.setText(labelPrefix + numClicks); (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

18. Adding Components to Containers JPanel panel = new JPanel(new GridLayout(0,1)); panel.add(button); panel.add(label); panel.setBorder(BorderFactory.createEmptyBorder(...)); • layout manager - an object that determines the size and position of each component added to the container (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

19. Adding Borders Around Components • the code that adds a border to the panel: pane.setBorder(BorderFactory.createEmptyBorder( 30, //top 30, //left 10, //bottom 30) //right ); (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

20. Handling Events • Every time the user types a character or pushes a mouse button, an event occurs • Any object can be notified of the event • All the object has to do is implement the appropriate interface and be registered as an event listener on the appropriate event source (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

21. SwingApplication class public class SwingApplication implements ActionListener { ... JButton button = new JButton("I'm a Swing button!"); button.addActionListener(this); .... public void actionPerformed(ActionEvent e) { numClicks++; label.setText(labelPrefix + numClicks); } } (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

22. Event handler • Every event handler requires three pieces of code: • In the declaration for the event handler class one line of code specifies that the class either implements a listener interface or extends a class that implements a listener interface • Another line of code registers an instance of the event handler class as a listener on one or more components • The event handler class has code that implements the methods in the listener interface (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

23. Kinds of events (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

24. Adding HTML • To use HTML in a component’s text, simply place the <HTML> tag at the beginning of the text string and then use any valid HTML code in the remainder of the string button = new JButton("<html><b><u>T</u>wo</b><br>lines</html>"); (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

25. Adding an Icon • Some Swing components can be decorated with an icon--a fixed-size image ImageIcon convertIcon =createImageIcon("images/convert.gif", "Convert temperature"); ... JButton convertTemp = new JButton(icon); (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

26. Setting the Default Button converterFrame.getRootPane().setDefaultButton(convertTemp); (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

27. Using Layout Managers • The Java platform supplies six commonly used layout managers: BorderLayout, BoxLayout, FlowLayout, GridLayout, GridBagLayout, and SpringLayout • JPanel objects use FlowLayout by default content panes (the main containers in JApplet, JDialog, and JFrame objects) use BorderLayout by default (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

28. Using Layout Managers 2 • As a rule, the only time you have to think about layout managers is when you create a JPanel or add components to a content pane JPanel pane = new JPanel(new BorderLayout()); … Container contentPane = frame.getContentPane(); contentPane.setLayout(new FlowLayout()); (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

29. Compound Borders // Add border around the select panel selectPanel.setBorder(BorderFactory.createCompoundBorder(BorderFactory.createTitledBorder("Select Phase"),BorderFactory.createEmptyBorder(5,5,5,5))); (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

30. Combo Boxes JComboBox phaseChoices = null; ... //Create combo box with lunar phase choices. String[] phases = { "New", "Waxing Crescent", "First Quarter", "Waxing Gibbous", "Full", "Waning Gibbous", "Third Quarter", "Waning Crescent" }; phaseChoices = new JComboBox(phases); phaseChoices.setSelectedIndex(START_INDEX); (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006

31. Handling Events on a Combo Box • The combo box fires an action event when the user selects an item from the combo box's drop-down list phaseChoices.addActionListener(this); ... public void actionPerformed(ActionEvent event) { if ("comboBoxChanged".equals(event.getActionCommand())) { //Update the icon to display the new phase phaseIconLabel.setIcon(images[phaseChoices.getSelectedIndex()]); } } (С) ЦТДО, каф. Искусственного интеллекта, ХНУРЭ, 2006