Chapter 13: Advanced GUIs and Graphics J ava P rogramming: From Problem Analysis to Program Design, From Problem Analysis to Program Design, Second Edition Second Edition

Java Programming: From Problem Analysis to Program Design, Second Edition2 Chapter Objectives  Learn about applets.  Explore the class Graphics.  Learn about the class Font.  Explore the class Color.  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.

Java Programming: From Problem Analysis to Program Design, Second Edition3 Inheritance Hierarchy of GUI Classes

Java Programming: From Problem Analysis to Program Design, Second Edition4 Constructors and Methods of the class Component

Java Programming: From Problem Analysis to Program Design, Second Edition5 Constructors and Methods of the class Component

Java Programming: From Problem Analysis to Program Design, Second Edition6 Constructors and Methods of the class Component

Java Programming: From Problem Analysis to Program Design, Second Edition7 Constructors and Methods of the class Component

Java Programming: From Problem Analysis to Program Design, Second Edition8 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.

Java Programming: From Problem Analysis to Program Design, Second Edition9 Applets

Java Programming: From Problem Analysis to Program Design, Second Edition10 Applets

Java Programming: From Problem Analysis to Program Design, Second Edition11 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.

Java Programming: From Problem Analysis to Program Design, Second Edition12 Applet Methods  init method:  Initializes variables.  Gets data from user.  Places various GUI components.  paint method:  Performs output.

Java Programming: From Problem Analysis to Program Design, Second Edition13 Skeleton of a Java Applet import java.awt.Graphics; import javax.swing.JApplet; public class WelcomeApplet extends JApplet { }

Java Programming: From Problem Analysis to Program Design, Second Edition14 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 }

Java Programming: From Problem Analysis to Program Design, Second Edition15 HTML to Run Applet

Java Programming: From Problem Analysis to Program Design, Second Edition16 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).

Java Programming: From Problem Analysis to Program Design, Second Edition17 class Font

Java Programming: From Problem Analysis to Program Design, Second Edition18 class Color  Shows text in different colors.  Changes background color of component.  Contained in package java.awt.

Java Programming: From Problem Analysis to Program Design, Second Edition19 class Color

Java Programming: From Problem Analysis to Program Design, Second Edition20 class Color

Java Programming: From Problem Analysis to Program Design, Second Edition21 class Color

Java Programming: From Problem Analysis to Program Design, Second Edition22 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.

Java Programming: From Problem Analysis to Program Design, Second Edition23 class Graphics

Java Programming: From Problem Analysis to Program Design, Second Edition24 Constructors and Methods for the class Graphics

Java Programming: From Problem Analysis to Program Design, Second Edition25 Constructors and Methods for the class Graphics

Java Programming: From Problem Analysis to Program Design, Second Edition26 Constructors and Methods for the class Graphics

Java Programming: From Problem Analysis to Program Design, Second Edition27 Constructors and Methods for the class Graphics

Java Programming: From Problem Analysis to Program Design, Second Edition28 Differences Between Applets and GUI Applications  Applets  Derived from JApplet.  No main method.  Uses init method.  Displayed by HTML.  Sets title in HTML.  Size set in HTML.  Applet closes when HTML doc closes.  GUI applications  Class extends JFrame.  Invokes main method.  Uses constructors.  Uses method setVisible.  Uses setTitle method.  Uses method setSize.  Closes with Exit button.

Java Programming: From Problem Analysis to Program Design, Second Edition29 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).

Java Programming: From Problem Analysis to Program Design, Second Edition30 Additional GUI Components  JTextArea  JCheckBox  JRadioButton  JComboBox  JList

Java Programming: From Problem Analysis to Program Design, Second Edition31 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.

Java Programming: From Problem Analysis to Program Design, Second Edition32 JTextArea

Java Programming: From Problem Analysis to Program Design, Second Edition33 JTextArea

Java Programming: From Problem Analysis to Program Design, Second Edition34 JTextArea Example

Java Programming: From Problem Analysis to Program Design, Second Edition35 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.

Java Programming: From Problem Analysis to Program Design, Second Edition36 JCheckBox

Java Programming: From Problem Analysis to Program Design, Second Edition37 Constructors and Methods of class JCheckBox

Java Programming: From Problem Analysis to Program Design, Second Edition38 Constructors and Methods of class JCheckBox

Java Programming: From Problem Analysis to Program Design, Second Edition39 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.

Java Programming: From Problem Analysis to Program Design, Second Edition40 JRadioButton

Java Programming: From Problem Analysis to Program Design, Second Edition41 JRadioButton

Java Programming: From Problem Analysis to Program Design, Second Edition42 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.

Java Programming: From Problem Analysis to Program Design, Second Edition43 JComboBox

Java Programming: From Problem Analysis to Program Design, Second Edition44 JComboBox

Java Programming: From Problem Analysis to Program Design, Second Edition45 JList

Java Programming: From Problem Analysis to Program Design, Second Edition46 JList

Java Programming: From Problem Analysis to Program Design, Second Edition47 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.

Java Programming: From Problem Analysis to Program Design, Second Edition48 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.

Java Programming: From Problem Analysis to Program Design, Second Edition49 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.

Java Programming: From Problem Analysis to Program Design, Second Edition50 Keyboard and Mouse Events

Java Programming: From Problem Analysis to Program Design, Second Edition51 Chapter Summary  Creating applets  class Font  class Graphics  class Color  Differences between applets and GUI applications  Converting GUI applications to applets

Java Programming: From Problem Analysis to Program Design, Second Edition52 Chapter Summary  GUI components:  JTextArea  JCheckBox  JRadioButton  Layout managers  Menus  Keyboard and mouse events