Java Programming: Advanced Topics 1 Common Elements of Graphical User Interfaces Chapter 6

Java Programming: Advanced Topics 2 Objectives Learn the characteristics of a graphical user interface Explore the contents of the Java Foundation Classes Discover how the JFC supports creating GUIs for the Java platform Design GUIs with layouts that dynamically adjust to screen resolution and window size Include predefined components such as text fields, buttons, and multimedia elements in your GUI

Java Programming: Advanced Topics 3 Objectives (Cont.) See how the JFC provides a framework for interacting with the user in event-driven programs Write code using component, container, and layout manager classes of the AWT and Swing State the name of the event class for any specified listener interface in the java.awt.event package Write code to implement the paintComponent method of a javax.swing.Jcomponent component

Java Programming: Advanced Topics 4 Main Features and Terminology of a GUI Components are predefined standard elements (such as buttons, text fields, frame windows, and dialog boxes) The layout managers control the way components are arranged within a container Graphics: drawing in the graphics context for a component Graphics context: is the area on the display screen where a component is positioned

Java Programming: Advanced Topics 5 Main Features and Terminology of a GUI (Cont.) Painting: the process of displaying components or refreshing the display of components on the screen Events can be triggered by the operating system or by user actions The adapter is a class that implements all the methods of the interface by providing empty methods for all of them Each listener interface that has more than one method also has a corresponding adapter class

Java Programming: Advanced Topics 6 Introducing the Java Foundation Classes The goal of the JFC is to simplify the development of 100% Pure Java programs for network or standalone environments The classes enable you to: –Design GUIs that reflect the operating system that is host to the JVM –Create your own platform-independent interface –Use a look and feel defined for the Java platform and common across all implementations of the JVM

Java Programming: Advanced Topics 7 Introducing the Java Foundation Classes

Java Programming: Advanced Topics 8 Introducing the Java Foundation Classes

Java Programming: Advanced Topics 9 Abstract Windowing Toolkit API

Java Programming: Advanced Topics 10 Abstract Windowing Toolkit API (Cont.)

Java Programming: Advanced Topics 11 Abstract Windowing Toolkit API (Cont.)

Java Programming: Advanced Topics 12 Event Model Define any class to be an event handler by implementing a listener interface Call a method of a component class to register the listener with the component When an event that relates to the component occurs, only the registered listeners are notified and passed a copy of the event The event model is consistent with the JavaBeans interface

Java Programming: Advanced Topics 13 Swing API The Swing API consists of more than 250 classes and 75 interfaces grouped into the following categories: –JComponent: extends the AWT class Container and a set of components that are subclasses of JComponent –Nonvisible support classes that provide important services –A set of related interfaces that are implemented by Swing component and support classes

Java Programming: Advanced Topics 14 Swing Components

Java Programming: Advanced Topics 15 Swing Components (Cont.)

Java Programming: Advanced Topics 16 Swing Components (Cont.)

Java Programming: Advanced Topics 17 Swing Components (Cont.)

Java Programming: Advanced Topics 18 Separable Model Architecture Swing components separate the manipulation of data associated with a component from the rendering or graphical-representation component and its contents The Swing API uses a separable model architecture Swing models use two different styles of notification: –Lightweight –Stateful The Swing API defines a set of model interfaces

Java Programming: Advanced Topics 19 Swing Model Interfaces

Java Programming: Advanced Topics 20 Swing Model Interfaces (Cont.)

Java Programming: Advanced Topics 21 An Example of JFC Program

Java Programming: Advanced Topics 22 Layout Managers Layout managers automate the positioning of components within containers Standard layout managers: –BorderLayout –FlowLayout –GridLayout –GridBagLayout –BoxLayout –CardLayout The javax.swing.JTabbedPane and javax.swing.JSplitPane containers in the Swing API have built-in layout characteristics

Java Programming: Advanced Topics 23 Layout Managers and Related Interfaces

Java Programming: Advanced Topics 24 Border Layouts The BorderLayout class implements the LayoutManager2 interface to support a container that holds up to five components: –North –South –West –East –Center By default, the JWindow, JFrame, and JDialog containers have border layouts

Java Programming: Advanced Topics 25 The BorderLayout Strategy

Java Programming: Advanced Topics 26 Flow Layouts The class FlowLayout implements the LayoutManager interface Components are arranged in a row across the area of the container Components in a flow layout retain their preferred size By default, JPanel objects have flow layouts

Java Programming: Advanced Topics 27 A FlowLayout Example

Java Programming: Advanced Topics 28 Grid Layouts The class GridLayout implements the LayoutManager2 interface GridLayout manager divides the area of the container into a grid of equally sized rows and columns Components are automatically put into the next cell, in a left to right order, filling rows from top to bottom

Java Programming: Advanced Topics 29 A GridLayout Example

Java Programming: Advanced Topics 30 Grid-Bag Layouts The class GridBagLayout implements the LayoutManager2 interface to support grid-bag layouts A grid-bag layout is based on a rectangular grid, and it uses a helper class, GridBagConstraints, to specify how each component should be located within the grid

Java Programming: Advanced Topics 31 A GridBagLayout Example

Java Programming: Advanced Topics 32 Events Events: objects that encapsulate changes in state that are initiated by the user or the operating system The AWT API includes the package java.awt.event of the classes that encapsulate the events that relate to the GUI components in your application or applet

Java Programming: Advanced Topics 33 AWT Event Classes

Java Programming: Advanced Topics 34 AWT Event Classes(Cont.)

Java Programming: Advanced Topics 35 Swing Event Classes

Java Programming: Advanced Topics 36 Selected Methods of the Event Classes

Java Programming: Advanced Topics 37 Selected Methods of the Event Classes (Cont.)

Java Programming: Advanced Topics 38 Events that Start Long Operations

Java Programming: Advanced Topics 39 Painting Painting: the act of drawing onto the graphics context of a component All objects that are instances of subclasses of java.awt.Component handle their own painting The key methods: –void paintComponent (Graphics context) –void paint (Graphics context) –void repaint (long time) –void update (Graphics context)

Java Programming: Advanced Topics 40 Basic Support for Graphics The AWT API provides basic graphics support through the class Graphics The drawing methods of the class Graphics are instance methods of the Graphics class, and each instance of Graphics is the graphics context for a component The Graphics class provides a number of methods for drawing onto a component

Java Programming: Advanced Topics 41 Java 2D API The basic support for drawing was lacking for high-quality graphics The goal was to create an API that addressed the needs of graphics professionals The Java 2D API was created and included as part of the JFC

Java Programming: Advanced Topics 42 Notable Java 2D Features

Java Programming: Advanced Topics 43 Summary The JFC consists of five major APIs, including the classes and interfaces in the AWT and Swing APIs that you use to program a GUI for an application or applet Layout managers are used to arrange the components in a way that adjusts for screen resolutions and window resizings Standard layout managers include BorderLayout, FlowLayout, GridLayout, GridBagLayout, Box, and CardLayout Each component class supports a number of events that are appropriate to its type of component

Java Programming: Advanced Topics 44 Summary (Cont.) The AWT contains a hierarchy of event classes for different kinds of user-initiated events, such as ComponentEvent, MouseEvent, KeyEvent, ItemEvent, TextEvent, and ActionEvent Each listener interface that has more than one method also has a corresponding adapter class Painting is the act of drawing onto the graphics context of a component, and drawing methods of the Graphics class are paintComponent, paint, and update methods of a component The goal of the Java 2D API addresses the needs of graphics professionals