Swing_Introduction.ppt
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The document provides an overview of Java Swing, a widget toolkit for building graphical user interfaces, detailing its principles, architecture, and components. Key topics include the containment hierarchy of widgets, event handling with listeners and action events, as well as examples of Swing applications. It emphasizes the separation of models and views while comparing Swing to the original Abstract Windowing Toolkit (AWT).
![10
Swing Hello World
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class HelloWorld {
public static void main(String[] args) {
JFrame frame = new JFrame("Hello World!");
frame.setSize(220, 200);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container contentPane = frame.getContentPane();
contentPane.setLayout(null);
JButton button = new JButton("Hello World!");
button.setLocation(30, 30);
button.setSize(150, 100);
contentPane.add(button);
frame.setVisible(true);
}
}](https://image.slidesharecdn.com/swingintroduction-231002231056-58ae88ba/85/Swing_Introduction-ppt-10-320.jpg)
![11
Swing Hello World
with Events
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class MyActionListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
Toolkit.getDefaultToolkit().beep();
}
}
...
public class HelloWorld {
public static void main(String[] args) {
...
JButton button = new JButton("Hello World!");
button.addActionListener(new MyActionListener());
...
}
}](https://image.slidesharecdn.com/swingintroduction-231002231056-58ae88ba/85/Swing_Introduction-ppt-11-320.jpg)
![12
Containment Hierarchy
of a Menu
…
public class MenuExample {
public static void main(String[] args) {
JFrame frame = new JFrame("My Frame");
frame.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE);
JMenu fileMenu = new JMenu("File");
fileMenu.add(new JMenuItem("New"));
fileMenu.add(new JMenuItem("Open"));
fileMenu.add(new JMenuItem("Close"));
JMenu editMenu = new JMenu("Edit");
editMenu.add(new JMenuItem("Undo"));
editMenu.add(new JMenuItem("Redo"));
editMenu.add(new JMenuItem("Cut"));
JMenuBar menubar = new JMenuBar();
menubar.add(fileMenu);
menubar.add(editMenu);
frame.setJMenuBar(menubar);
frame.setVisible(true);
} }
File Edit
Undo
Redo
Cut
File Edit
New
Open
Close](https://image.slidesharecdn.com/swingintroduction-231002231056-58ae88ba/85/Swing_Introduction-ppt-12-320.jpg)
![13
Handling Menu Events
...
public class MenuActionListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(MenuExample.frame,
"Got an ActionEvent at " + new Date(e.getWhen())
+ " from " + e.getSource().getClass());
} }
...
public class MenuExample {
static JFrame frame;
public static void main(String[] args) {
...
JMenuItem item = new JMenuItem("Close");
item.addActionListener(new MenuActionListener());
fileMenu.add(item);
...
} }](https://image.slidesharecdn.com/swingintroduction-231002231056-58ae88ba/85/Swing_Introduction-ppt-13-320.jpg)
![14
Defining Event Listeners with Anonynous
Classes
• Use new Classname() {…} or new Interfacename(){…} to
create a single object of an anonymous subclass of the given
class/interface
• Anonymous classes can access final variables of their context (i.e.
final variables of the method or class they are created in)
...
public class MenuExample {
public static void main(String[] args) {
final JFrame frame = new JFrame("My Frame");
...
JMenuItem item = new JMenuItem("Close");
item.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int n = JOptionPane.showOptionDialog(frame,...
}
});
...
} }](https://image.slidesharecdn.com/swingintroduction-231002231056-58ae88ba/85/Swing_Introduction-ppt-14-320.jpg)
Swing_Introduction.ppt
- 2. 2 Introduction to Java Swing
- 3. 3 AWT vs. Swing Abstract Windowing Toolkit (AWT) • Original Java GUI toolkit • Wrapper API for native GUI components • Lowest-common denominator for all Java host environments Swing • Implemented entirely in Java on top of AWT • Richer set of GUI components • Pluggable look-and-feel support
- 4. 4 Swing Design Principles • GUI is built as containment hierarchy of widgets (i.e. the parent-child nesting relation between them) • Event objects and event listeners – Event object: is created when event occurs (e.g. click), contains additional info (e.g. mouse coordinates) – Event listener: object implementing an interface with an event handler method that gets an event object as argument • Separation of Model and View: – Model: the data that is presented by a widget – View: the actual presentation on the screen
- 5. 5 Partial AWT and Swing Class Hierarchy java.lang.Object Component MenuComponent CheckboxGroup Button Checkbox Canvas Choice Container Label List Scrollbar TextComponent JComponent Window Frame JFrame Dialog JDialog Panel Scrollpane Applet JApplet java.awt.* javax.swing.* JLabel JList AbstractButton JButton JPanel JScrollpane
- 6. 6 Swing Widgets (more on this next lecture) Top-Level Containers JFrame JPanel JSplitPane JTabbedPane JDialog JScrollPane General-Purpose Containers JButton JCheckbox JRadioButton and ButtonGroup JCombobox JLabel JList Menu
- 8. 8 The Initial Swing GUI Containment Hierarchy File Edit Undo Redo Cut Frame / Dialog / Applet Root Pane Layered Pane Content Pane Glass Pane a 3D model enables menus to pop up above the content pane allows for interception of mouse events and painting across GUI components
- 9. 9 The Initial Swing GUI Containment Hierarchy aTopLevelContainer: JFrame or JDialog or JApplet rootPane: JRootPane (JPanel) glassPane: java.awt.Component (JPanel) contentPane: java.awt.Container layeredPane: JLayeredPane menuBar: JMenuBar optional
- 10. 10 Swing Hello World import java.awt.*; import java.awt.event.*; import javax.swing.*; public class HelloWorld { public static void main(String[] args) { JFrame frame = new JFrame("Hello World!"); frame.setSize(220, 200); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); Container contentPane = frame.getContentPane(); contentPane.setLayout(null); JButton button = new JButton("Hello World!"); button.setLocation(30, 30); button.setSize(150, 100); contentPane.add(button); frame.setVisible(true); } }
- 11. 11 Swing Hello World with Events import java.awt.*; import java.awt.event.*; import javax.swing.*; public class MyActionListener implements ActionListener { public void actionPerformed(ActionEvent e) { Toolkit.getDefaultToolkit().beep(); } } ... public class HelloWorld { public static void main(String[] args) { ... JButton button = new JButton("Hello World!"); button.addActionListener(new MyActionListener()); ... } }
- 12. 12 Containment Hierarchy of a Menu … public class MenuExample { public static void main(String[] args) { JFrame frame = new JFrame("My Frame"); frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE); JMenu fileMenu = new JMenu("File"); fileMenu.add(new JMenuItem("New")); fileMenu.add(new JMenuItem("Open")); fileMenu.add(new JMenuItem("Close")); JMenu editMenu = new JMenu("Edit"); editMenu.add(new JMenuItem("Undo")); editMenu.add(new JMenuItem("Redo")); editMenu.add(new JMenuItem("Cut")); JMenuBar menubar = new JMenuBar(); menubar.add(fileMenu); menubar.add(editMenu); frame.setJMenuBar(menubar); frame.setVisible(true); } } File Edit Undo Redo Cut File Edit New Open Close
- 13. 13 Handling Menu Events ... public class MenuActionListener implements ActionListener { public void actionPerformed(ActionEvent e) { JOptionPane.showMessageDialog(MenuExample.frame, "Got an ActionEvent at " + new Date(e.getWhen()) + " from " + e.getSource().getClass()); } } ... public class MenuExample { static JFrame frame; public static void main(String[] args) { ... JMenuItem item = new JMenuItem("Close"); item.addActionListener(new MenuActionListener()); fileMenu.add(item); ... } }
- 14. 14 Defining Event Listeners with Anonynous Classes • Use new Classname() {…} or new Interfacename(){…} to create a single object of an anonymous subclass of the given class/interface • Anonymous classes can access final variables of their context (i.e. final variables of the method or class they are created in) ... public class MenuExample { public static void main(String[] args) { final JFrame frame = new JFrame("My Frame"); ... JMenuItem item = new JMenuItem("Close"); item.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { int n = JOptionPane.showOptionDialog(frame,... } }); ... } }
- 15. 15 Different Kinds of Swing Events Low-level events • MouseEvent: Component got mouse-down, mouse-move, etc. • KeyEvent: Component got key-press, key-release, etc. • ComponentEvent: Component resized, moved, etc. • ContainerEvent: Container's contents changed because a component was added or removed • FocusEvent: Component got focus or lost focus • WindowEvent: Window opened, closed, etc. High-level semantic events • ActionEvent: Main action of control invoked (e.g. JButton click) • AdjustmentEvent: Value was adjusted (e.g. JScrollBar moved) • ItemEvent: Item was selected or deselected (e.g. in JList) • TextEvent: Text in component has changed (e.g in JTextField)
- 16. 16 Events, Listeners, Adapters and Handler Methods Event Listener / Adapter Handler Methods ActionEvent ActionListener actionPerformed AdjustmentEvent AdjustmentListener adjustmentValueChanged MouseEvent MouseListener MouseAdapter mouseClicked mouseEntered mouseExited mousePressed mouseReleased KeyEvent KeyListener KeyAdapter keyPressed keyReleased keyTyped ComponentEvent ComponentListener ComponentAdapter componentShown componentHidden componentMoved componentResized Adapter classes with empty methods for Listener interfaces with >1 methods
- 17. 17 Summary • Desktop environments consist of: – Windowing System: handles input/output – Widget Toolkit: draws widgets and dispatches their events – Window Manager: takes care of windows • Swing is a widget toolkit for Java – GUI as containment hierarchy of widgets – Event objects and event listeners References: http://java.sun.com/docs/books/tutorial/uiswing/ http://www.javabeginner.com/java-swing-tutorial.htm