INTRODUCTION TO JAVA PROGRAMMING教学（华南理工）12slide-GUI.pptVIP

Introduction to Java Programming Chapter12 GUI Basics Objectives To distinguish simple GUI components (§12.2). To describe the Java GUI API hierarchy (§12.3). To create user interfaces using frames, panels, and simple UI components (§12.4). To understand the role of layout managers (§12.5). To use the FlowLayout, GridLayout, and BorderLayout managers to layout components in a container (§12.5). To specify colors and fonts using the Color and Font classes (§12.6-12.7). To use JPanel as subcontainers (§12.8). Creating GUI Objects // Create a button with text OK JButton jbtOK = new JButton(OK); ? // Create a label with text Enter your name: JLabel jlblName = new JLabel(Enter your name: ); ? // Create a text field with text Type Name Here JTextField jtfName = new JTextField(Type Name Here); ? // Create a check box with text bold JCheckBox jchkBold = new JCheckBox(Bold); ? // Create a radio button with text red JRadioButton jrbRed = new JRadioButton(Red); ? // Create a combo box with choices red, green, and blue JComboBox jcboColor = new JComboBox(new String[]{Red, Green, Blue}); Swing vs. AWT So why do the GUI component classes have a prefix J? Instead of JButton, why not name it simply Button? In fact, there is a class already named Button in the java.awt package. When Java was introduced, the GUI classes were bundled in a library known as the Abstract Windows Toolkit (AWT). For every platform on which Java runs, the AWT components are automatically mapped to the platform-specific components through their respective agents, known as peers. AWT is fine for developing simple graphical user interfaces, but not for developing comprehensive GUI projects. Besides, AWT is prone to platform-specific bugs because its peer-based approach relies heavily on the underlying platform. With the release of Java 2, the AWT user-interface components were replaced by a more robust, versatile, and flexible library known as Swing components. Swing components are pai