java面向对象编程3.2.1

1、 Swing components are based on AWT classes Java 2 released Swing as an alternative to AWT AWT uses platform-specific GUI components Swing is less reliant on platform-specific componentsmorelessheavyweightcomponentsAWTlightweightcomponentsSwingreliance on platform-specific GUI componentsimport javax.

2、swing.*;import java.awt.*; import java.awt.event.*; ObjectColorcontainerComponentLayoutManagerPanelWindowAppletFrameDialogJComponentJAppletJFrameJDialoglightweightheavyweightSwingAWTprimitivecontainerEvery widget is a container!Heavyweight ComponentsEvery program with a Swing GUI must have at least

3、one top-level Swing container.JFrame implements a single main windowJDialog creates a dialog window.JApplet implements an applet display area within a browser window. FrameMenu BarContent Pane JPanelJScrollPaneJToolBarJSplitPaneJTabbedPane3.2.1 Swing Components and Containers 3.2.1 Swing Components

4、and Containers Component JLabelComponent JLabelComponents of class Components of class JLabelJLabel can display text, an image, or both. can display text, an image, or both. import java.awt.*; import javax.swing.*; public class JLabelDemo extends JPanel private JLabel labelLeft; private JLabel label

5、Center; private JLabel labelRight; public static void main(String args) JFrame frame = new JFrame(JLabelDemo); frame.setContentPane(new JLabelDemo(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.pack(); / Adjust the size of the window frame.setVisible(true); public JLabelDemo() setLay

6、out(new GridLayout(1, 3); setBackground(Color.white); ImageIcon icon = new ImageIcon(images/bananas.gif, an image with bananas); labelLeft = new JLabel(Hello, icon, JLabel.CENTER); labelCenter = new JLabel(Hello); labelRight = new JLabel(icon); labelLeft.setVerticalTextPosition(JLabel.BOTTOM); label

7、Left.setHorizontalTextPosition(JLabel.CENTER); labelLeft.setFont(new Font(Serif, Font.BOLD, 16); labelCenter.setHorizontalAlignment(JLabel.CENTER); labelCenter.setFont(new Font(Serif, Font.BOLD, 30); add(labelLeft); add(labelCenter); add(labelRight); Component JButtonComponent JButtonComponents of c

8、lass JButton can display text, an image, or both. Component JRadioButtonComponent JRadioButtonComponents of class JRadioButton can be selected or deselected by the user. If JRadioButton components are grouped, by means of the class ButtonGroup, only one button at a time can be selected. Component JT

9、extFieldComponent JTextFieldComponents of class JTextField let the user enter (or edit) a small quantity of text. These components are also used to display small amounts of text. import java.awt.*; import javax.swing.*; public class JTextFieldDemo extends JPanel private JLabel labelCountry; private

10、JLabel labelCapital; private JTextField textFieldCountry; private JTextField textFieldCapital; public static void main(String args) JFrame frame = new JFrame(JTextFieldDemo); frame.setContentPane(new JTextFieldDemo(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.pack(); / Adjust the s

11、ize of the window frame.setVisible(true); public JTextFieldDemo() setLayout(new GridLayout(2, 1); setBackground(Color.white); labelCountry = new JLabel(Country:); textFieldCountry = new JTextField(Spain, 10); labelCapital = new JLabel(Capital:); textFieldCapital = new JTextField(Madrid, 10); textFie

12、ldCapital.setBackground(new Color(150, 0, 0); textFieldCapital.setForeground(Color.white); textFieldCapital.setHorizontalAlignment(JTextField.CENTER); textFieldCapital.setEditable(false); JPanel panelCountry = new JPanel(); panelCountry.setBackground(Color.white); panelCountry.add(labelCountry); pan

13、elCountry.add(textFieldCountry); add(panelCountry); JPanel panelCapital = new JPanel(); panelCapital.setBackground(Color.white); panelCapital.add(labelCapital); panelCapital.add(textFieldCapital); add(panelCapital); Component JTextAreaComponent JTextAreaComponents of class JTextArea let the user ent

14、er (or edit) multiple lines of text. A JTextArea component does not have scroll bars. If scroll bars are needed, the JTextArea is wrapped in a JScrollPane, which provides the scroll bars. import java.awt.*; import javax.swing.*; public class JTextAreaDemo extends JPanel private JTextArea textAreaOne

15、; private JTextArea textAreaTwo; public static void main(String args) JFrame frame = new JFrame(JTextAreaDemo); frame.setContentPane(new JTextAreaDemo(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.pack(); / Adjust the size of the window frame.setVisible(true); public JTextAreaDemo()

16、 setBackground(Color.white); String text = Line1nLine2nLine3nLine4nLine5n + Line6nLine7nLine8nLine9nLine10n; textAreaOne = new JTextArea(text, 7, 10); textAreaTwo = new JTextArea(text, 7, 10); textAreaOne.setBackground(new Color(0, 0, 150); textAreaTwo.setBackground(new Color(0, 150, 0); textAreaOne

17、.setForeground(Color.white); textAreaTwo.setForeground(Color.white); textAreaTwo.setEditable(false); add(new JScrollPane(textAreaOne, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED); add(new JScrollPane(textAreaTwo, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SC