Chapter 13: Advanced GUIs and Graphics Java Programming: Program Design Including Data Structures

Chapter Objectives Learn about applets Explore the class Graphics Learn about the class Font Explore the class Color Java Programming: Program Design Including Data Structures

Chapter Objectives (continued) 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: Program Design Including Data Structures

Inheritance Hierarchy of GUI Classes Java Programming: Program Design Including Data Structures

Constructors and Methods of the class Component Java Programming: Program Design Including Data Structures

Constructors and Methods of the class Component Java Programming: Program Design Including Data Structures

Constructors and Methods of the class Component Java Programming: Program Design Including Data Structures

Constructors and Methods of the class Component Java Programming: Program Design Including Data Structures

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: Program Design Including Data Structures

Applets Java Programming: Program Design Including Data Structures

Applets (continued) Java Programming: Program Design Including Data Structures

Applets (continued) 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: Program Design Including Data Structures

Applet Methods init method: paint method: Initializes variables Gets data from user Places various GUI components paint method: Performs output Java Programming: Program Design Including Data Structures

Skeleton of a Java Applet import java.awt.Graphics; import javax.swing.JApplet; public class WelcomeApplet extends JApplet { } Java Programming: Program Design Including Data Structures

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: Program Design Including Data Structures

HTML to Run Applet Java Programming: Program Design Including Data Structures

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: Program Design Including Data Structures

class Font (continued) Java Programming: Program Design Including Data Structures

class Color Shows text in different colors Changes background color of component Contained in package java.awt Java Programming: Program Design Including Data Structures

class Color (continued) Java Programming: Program Design Including Data Structures

class Color (continued) Java Programming: Program Design Including Data Structures

class Color (continued) Java Programming: Program Design Including Data Structures

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: Program Design Including Data Structures

class Graphics Java Programming: Program Design Including Data Structures

Constructors and Methods for the class Graphics Java Programming: Program Design Including Data Structures

Constructors and Methods for the class Graphics Java Programming: Program Design Including Data Structures

Constructors and Methods for the class Graphics Java Programming: Program Design Including Data Structures

Constructors and Methods for the class Graphics Java Programming: Program Design Including Data Structures

Differences Between Applets and GUI Applications 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: Program Design Including Data Structures

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: Program Design Including Data Structures

Additional GUI Components JTextArea JCheckBox JRadioButton JComboBox JList Java Programming: Program Design Including Data Structures

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: Program Design Including Data Structures

JTextArea Java Programming: Program Design Including Data Structures

JTextArea (continued) Java Programming: Program Design Including Data Structures

JTextArea Example Java Programming: Program Design Including Data Structures

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: Program Design Including Data Structures

JCheckBox Java Programming: Program Design Including Data Structures

Constructors and Methods of class JCheckBox Java Programming: Program Design Including Data Structures

Constructors and Methods of class JCheckBox Java Programming: Program Design Including Data Structures

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: Program Design Including Data Structures

JRadioButton Java Programming: Program Design Including Data Structures

JRadioButton Java Programming: Program Design Including Data Structures

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: Program Design Including Data Structures

JComboBox (continued) Java Programming: Program Design Including Data Structures

JComboBox (continued) Java Programming: Program Design Including Data Structures

JList Java Programming: Program Design Including Data Structures

JList (continued) Java Programming: Program Design Including Data Structures

Layout Managers FlowLayout GridLayout 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: Program Design Including Data Structures

Layout Managers (continued) 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: Program Design Including Data Structures

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: Program Design Including Data Structures

Keyboard and Mouse Events Java Programming: Program Design Including Data Structures

Chapter Summary Creating applets class Font class Graphics class Color Differences between applets and GUI applications Converting GUI applications to applets Java Programming: Program Design Including Data Structures

Chapter Summary (continued) GUI components: JTextArea JCheckBox JRadioButton Layout managers Menus Keyboard and mouse events Java Programming: Program Design Including Data Structures