Chapter 13: Advanced GUIs and
Graphics
Java Programming:
From Problem Analysis to Program Design,
Second Edition
Chapter Objectives
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Learn about applets.
Explore the class Graphics.
Learn about the class Font.
Explore the class Color.
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Learn to use additional layout managers.
Become familiar with more GUI components.
Learn how to create menu-based programs.
Explore how to handle key and mouse events.
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Inheritance Hierarchy of GUI Classes
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Constructors and Methods of the class Component
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Constructors and Methods of the class Component
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Constructors and Methods of the class Component
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Constructors and Methods of the class Component
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Applets
 A Java program that is embedded within a Web page
and executed by a Web browser.
 Create an applet by extending the class
JApplet.
 class JApplet is contained in package
javax.swing.
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Applets
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Applets
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Applets
 No main method.
 Methods init, start, and paint guaranteed to
be invoked in sequence.
 To develop an applet:
 Override any/all of the methods above.
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Applet Methods
 init method:
 Initializes variables.
 Gets data from user.
 Places various GUI components.
 paint method:
 Performs output.
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Skeleton of a Java Applet
import java.awt.Graphics;
import javax.swing.JApplet;
public class WelcomeApplet extends JApplet
{
}
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Applet Displaying Welcome Message
//Welcome Applet
import java.awt.Graphics;
import javax.swing.JApplet;
public class WelcomeApplet extends JApplet
{
public void paint(Graphics g)
{
super.paint(g);
//Line 1
g.drawString("Welcome to Java Programming" ,
30, 30);
//Line 2
}
}
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HTML to Run Applet
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class Font
 Shows text in different fonts.
 Contained in package java.awt.
 Available fonts:
 Serif/Sans Serif
 Monospaced
 Dialog/DialogInput
 Arguments for constructor:
 String specifying the font face name.
 int value specifying font style.
 int value specifying font size.
 Expressed in points (72 points = 1 inch) .
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class Font
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class Color
 Shows text in different colors.
 Changes background color of component.
 Contained in package java.awt.
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class Color
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class Color
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class Color
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class Graphics
 Provides methods for drawing items such as lines,
ovals, and rectangles on the screen.
 Contains methods to set the properties of graphic
elements including clipping areas, fonts, and colors.
 Contained in the package java.awt.
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class Graphics
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Constructors and Methods for the
class Graphics
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Constructors and Methods for the
class Graphics
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Constructors and Methods for the
class Graphics
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Constructors and Methods for the
class Graphics
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Differences Between Applets and
GUI Applications
 Applets
 GUI applications
 Derived from JApplet.
 Class extends JFrame.
 No main method.
 Invokes main method.
 Uses init method.
 Uses constructors.
 Displayed by HTML.
 Uses method setVisible.
 Sets title in HTML.
 Uses setTitle method.
 Size set in HTML.
 Uses method setSize.
 Applet closes when
HTML doc closes.
 Closes with Exit button.
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Converting a GUI Application
to an Applet
 Change JFrame to JApplet.
 Change constructor to method init.
 Remove method calls such as setVisible,
setTitle, setSize.
 Remove the method main.
 If applicable, remove Exit button and all code
associated with it (for example, action listener).
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Additional GUI Components
 JTextArea
 JCheckBox
 JRadioButton
 JComboBox
 JList
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JTextArea
 Can collect multiple lines of input from user.
 Can display multiple lines of output.
 Pressing Enter key separates lines of text.
 Each line ends with newline character (\n).
 Derived from class JTextComponent.
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JTextArea
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JTextArea
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JTextArea Example
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JCheckBox
 User selects from predefined values.
 Example of a toggle button.
 Clicking JCheckBox generates item event.
 Use interface ItemListener and its abstract
method itemStateChanged to handle event.
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JCheckBox
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Constructors and Methods of class JCheckBox
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Constructors and Methods of class JCheckBox
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JRadioButton
 Created same way as check boxes.
 Placed in content pane of applet.
 Forces user to select only one radion button at a
time.
 You create a button group to group radio buttons.
 Generates an ItemEvent.
 interface ItemListener and method
itemStateChanged used to handle events.
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JRadioButton
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JRadioButton
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JComboBox
 Commonly known as a drop-down list.
 Used to select an item from a list of possibilities.
 Generates an ItemEvent.
 Event monitored by ItemListener.
 ItemListener invokes method
itemStateChanged.
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JComboBox
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JComboBox
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JList
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JList
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Layout Managers
 FlowLayout
 Default layout manager.
 Places components from left to right until no more
items can be placed.
 Can align each line left, center, or right.
 Default alignment: LEFT.
 GridLayout
 Similar to FlowLayout.
 All rows (columns) have same number of
components.
 All components have the same size.
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Layout Managers
 BorderLayout
 Items placed into one of five specific regions:
 NORTH/SOUTH
 EAST/WEST
 CENTER
 NORTH and SOUTH components extend
horizontally (completely span one edge to the other).
 EAST and WEST components extend vertically
between components in NORTH and SOUTH
regions.
 CENTER component expands to occupy any unused
regions.
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Menus
 Allow for various functions without cluttering GUI
with too many components.
 Can be attached to objects such as JFrame and
JApplet (setJMenuBar method).
 To set a menu bar:
private JMenuBar menuMB =
new JMenuBar();
setJMenuBar(menuMB);
 Add menus to menu bar; add menu items to menu.
 Order of menus added = order of appearance.
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Keyboard and Mouse Events
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Chapter Summary
 Creating applets
 class Font
 class Graphics
 class Color
 Differences between applets and GUI applications
 Converting GUI applications to applets
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Chapter Summary
 GUI components:
 JTextArea
 JCheckBox
 JRadioButton
 Layout managers
 Menus
 Keyboard and mouse events
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