例6.1声明一个面板子类，面板子类对象有3个选择框。

  1. class Panel1 extends JPanel {
  2. 	JCheckBox box1, box2, box3;
  3.  
  4. 	Panel1() {
  5. 		box1 = new JCheckBox("足球");
  6. 		box2 = new JCheckBox("排球");
  7. 		box3 = new JCheckBox("篮球");
  8. 		add(box1);
  9. 		add(box2);
  10. 		add(box3);
  11. 	}
  12. }

例6.2处理选择项目事件的小应用程序。

  1. import java.applet.*;
  2. import javax.swing.*;
  3. import java.awt.*;
  4. import java.awt.event.*;
  5.  
  6. class Panel1 extends JPanel {// 扩展Panel类
  7. 	JRadioButton box1, box2, box3;
  8. 	ButtonGroup g;
  9.  
  10. 	Panel1() {// 3个单选按钮为一组
  11. 		setLayout(new GridLayout(1, 3));
  12. 		g = new ButtonGroup();
  13. 		box1 = new JRadioButton(MyWindow.fName[0] + "计算机", false);
  14. 		box2 = new JRadioButton(MyWindow.fName[1] + "计算机", false);
  15. 		box3 = new JRadioButton(MyWindow.fName[2] + "计算机", false);
  16. 		g.add(box1);
  17. 		g.add(box2);
  18. 		g.add(box3);
  19. 		add(box1);
  20. 		add(box2);
  21. 		add(box3);
  22. 		add(new JLabel("计算机3选1"));
  23. 	}
  24. }
  25.  
  26. class Panel2 extends JPanel {// 扩展Panel类
  27. 	JCheckBox box1, box2, box3;
  28. 	ButtonGroup g;
  29.  
  30. 	Panel2() {// 3个选择框为一组
  31. 		setLayout(new GridLayout(1, 3));
  32. 		g = new ButtonGroup();
  33. 		box1 = new JCheckBox("购买1台");
  34. 		box2 = new JCheckBox("购买2台");
  35. 		box3 = new JCheckBox("购买3台");
  36. 		g.add(box1);
  37. 		g.add(box2);
  38. 		g.add(box3);
  39. 		add(box1);
  40. 		add(box2);
  41. 		add(box3);
  42. 		add(new JLabel("选择1、2或3"));
  43. 	}
  44. }
  45.  
  46. class MyWindow extends JFrame implements ItemListener {
  47. 	Panel1 panel1;
  48. 	Panel2 panel2;
  49. 	JLabel label1, label2;
  50. 	JTextArea text1, text2;
  51. 	static String fName[] = { "HP", "IBM", "DELL" };// 公司名称表
  52. 	static double priTbl[][] = { { 1.20, 1.15, 1.10 }, { 1.70, 1.65, 1.60 }, { 1.65, 1.60, 1.58 } };// 产品数量价格对照表
  53. 	static int production = -1;// 产品标志
  54.  
  55. 	MyWindow(String s) {
  56. 		super(s);
  57. 		Container con = this.getContentPane();
  58. 		con.setLayout(new GridLayout(3, 2));
  59. 		this.setLocation(100, 100);
  60. 		this.setSize(400, 100);
  61. 		panel1 = new Panel1();
  62. 		panel2 = new Panel2();
  63. 		label1 = new JLabel("产品介绍", JLabel.CENTER);
  64. 		label2 = new JLabel("产品价格", JLabel.CENTER);
  65. 		text1 = new JTextArea();
  66. 		text2 = new JTextArea();
  67. 		con.add(label1);
  68. 		con.add(label2);
  69. 		con.add(panel1);
  70. 		con.add(panel2);
  71. 		con.add(text1);
  72. 		con.add(text2);
  73. 		panel1.box1.addItemListener(this);
  74. 		panel1.box2.addItemListener(this);
  75. 		panel1.box3.addItemListener(this);
  76. 		panel2.box1.addItemListener(this);
  77. 		panel2.box2.addItemListener(this);
  78. 		panel2.box3.addItemListener(this);
  79. 		this.setVisible(true);
  80. 		this.pack();
  81. 	}
  82.  
  83. 	public void itemStateChanged(ItemEvent e) {
  84. 		if (e.getItemSelectable() == panel1.box1) {
  85. 			production = 0;
  86. 			text1.setText(fName[0] + "公司生产");
  87. 			text2.setText("");
  88. 		} else if (e.getItemSelectable() == panel1.box2) {
  89. 			production = 1;
  90. 			text1.setText(fName[1] + "公司生产");
  91. 			text2.setText("");
  92. 		} else if (e.getItemSelectable() == panel1.box3) {
  93. 			production = 2;
  94. 			text1.setText(fName[2] + "公司生产");
  95. 			text2.setText("");
  96. 		} else {
  97. 			if (production == -1) {
  98. 				return;
  99. 			}
  100. 			if (e.getItemSelectable() == panel2.box1) {
  101. 				text2.setText("" + priTbl[production][0] + "万元/台");
  102. 			} else if (e.getItemSelectable() == panel2.box2) {
  103. 				text2.setText("" + priTbl[production][1] + "万元/台");
  104. 			} else if (e.getItemSelectable() == panel2.box3) {
  105. 				text2.setText("" + priTbl[production][2] + "万元/台");
  106. 			}
  107. 		}
  108. 	}
  109. }
  110.  
  111. public class Example6_2 {
  112. 	MyWindow myWin = new MyWindow("选择项目处理示例程序");
  113. }

例6.3小应用程序有两个列表，第一个只允许单选，第二个列表允许多选。

  1. import java.applet.*;
  2. import javax.swing.*;
  3. import java.awt.*;
  4. import javax.swing.event.*;
  5.  
  6. class MyWindow extends JFrame implements ListSelectionListener {
  7. 	JList list1, list2;
  8. 	String news[] = { "人民日报", "新民晚报", "浙江日报", "文汇报" };
  9. 	String sports[] = { "足球", "排球", "乒乓球", "篮球" };
  10. 	JTextArea text;
  11.  
  12. 	MyWindow(String s) {
  13. 		super(s);
  14. 		Container con = getContentPane();
  15. 		con.setBackground(Color.BLUE);
  16. 		con.setLayout(new GridLayout(2, 2));
  17. 		con.setSize(200, 500);
  18. 		list1 = new JList(news);
  19. 		list1.setVisibleRowCount(3);
  20. 		list1.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
  21. 		list1.addListSelectionListener(this);
  22. 		list2 = new JList(sports);
  23. 		list2.setVisibleRowCount(2);
  24. 		list2.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
  25. 		list2.addListSelectionListener(this);
  26. 		con.add(list1);
  27. 		con.add(list2);
  28. 		text = new JTextArea(10, 20);
  29. 		con.add(text);
  30. 		this.setVisible(true);
  31. 		this.pack();
  32. 	}
  33.  
  34. 	public void valueChanged(ListSelectionEvent e) {
  35. 		if (e.getSource() == list1) {
  36. 			text.setText(null);
  37. 			Object listValue = ((JList) e.getSource()).getSelectedValue();
  38. 			String seleName = listValue.toString();
  39. 			for (int i = 0; i < news.length; i++) {
  40. 				if (news[i].equals(seleName)) {
  41. 					text.append(seleName + "：被选中\n");
  42. 				}
  43. 			}
  44. 		} else if (e.getSource() == list2) {
  45. 			text.setText(null);
  46. 			int tempList[] = list2.getSelectedIndices();// 获得选中索引
  47. 			for (int i = 0; i < tempList.length; i++) {
  48. 				text.append(sports[tempList[i]] + "：被选中\n");
  49. 			}
  50. 		}
  51. 	}
  52. }
  53.  
  54. public class Example6_3 extends Applet {
  55. 	MyWindow myWin = new MyWindow("列表示例");
  56. }

例6.4一个说明组合框用法的应用程序。

  1. import javax.swing.*;
  2. import java.awt.*;
  3. import java.awt.event.*;
  4.  
  5. public class Example6_4 {
  6. 	public static void main(String[] args) {
  7. 		ComboBoxDemo myComboBoxGUI = new ComboBoxDemo();
  8. 	}
  9. }
  10.  
  11. class ComboBoxDemo extends JFrame implements ActionListener, ItemListener {
  12. 	public static final int Width = 350;
  13. 	public static final int Height = 150;
  14. 	String proList[] = { "踢足球", "打篮球", "打排球" };
  15. 	JTextField text;
  16. 	JComboBox comboBox;
  17.  
  18. 	public ComboBoxDemo() {
  19. 		setSize(Width, Height);
  20. 		setTitle("组合框使用示意程序");
  21. 		Container conPane = getContentPane();
  22. 		conPane.setBackground(Color.BLUE);
  23. 		conPane.setLayout(new FlowLayout());
  24. 		comboBox = new JComboBox(proList);
  25. 		comboBox.addActionListener(this);
  26. 		comboBox.addItemListener(this);
  27. 		comboBox.setEditable(true);
  28. 		conPane.add(comboBox);
  29. 		text = new JTextField(10);
  30. 		conPane.add(text);
  31. 		this.setVisible(true);
  32. 	}
  33.  
  34. 	public void actionPerformed(ActionEvent e) {
  35. 		if (e.getSource() == comboBox) {
  36. 			text.setText(comboBox.getSelectedItem().toString());
  37. 		}
  38. 	}
  39.  
  40. 	public void itemStateChanged(ItemEvent e) {
  41. 		if (e.getSource() == comboBox) {
  42. 			text.setText(comboBox.getSelectedItem().toString());
  43. 		}
  44. 	}
  45. }

例6.5小应用程序示意窗口有菜单条的实现方法。

  1. import java.applet.*;
  2. import javax.swing.*;
  3. import java.awt.*;
  4. import java.awt.event.*;
  5.  
  6. class MenuWindow extends JFrame implements ActionListener {
  7. 	public static JTextField text;
  8.  
  9. 	private void addItem(JMenu menu, String menuName, ActionListener listener) {
  10. 		JMenuItem anItem = new JMenuItem(menuName);
  11. 		anItem.setActionCommand(menuName);
  12. 		anItem.addActionListener(listener);
  13. 		menu.add(anItem);
  14. 	}
  15.  
  16. 	public MenuWindow(String s, int w, int h) {
  17. 		setTitle(s);
  18. 		Container con = this.getContentPane();
  19. 		con.setLocation(100, 100);
  20. 		this.setSize(w, h);
  21. 		JMenu menu1 = new JMenu("体育");
  22. 		addItem(menu1, "跑步", this);
  23. 		addItem(menu1, "跳绳", this);
  24. 		addItem(menu1, "打球", this);
  25. 		JMenu menu2 = new JMenu("娱乐");
  26. 		addItem(menu2, "唱歌", this);
  27. 		addItem(menu2, "跳舞", this);
  28. 		addItem(menu2, "游戏", this);
  29. 		JMenuBar menubar = new JMenuBar();
  30. 		text = new JTextField();
  31. 		menubar.add(menu1);
  32. 		menubar.add(menu2);
  33. 		setJMenuBar(menubar);
  34. 		con.add(text, BorderLayout.NORTH);
  35. 	}
  36.  
  37. 	public void actionPerformed(ActionEvent e) {
  38. 		text.setText(e.getActionCommand() + "菜单项被选中！");
  39. 	}
  40. }
  41.  
  42. public class Example6_5 extends Applet implements ActionListener {
  43.  
  44. 	MenuWindow window;
  45. 	JButton button;
  46. 	boolean bflg;
  47.  
  48. 	public void init() {
  49. 		button = new JButton("打开我的体育娱乐之窗");
  50. 		bflg = true;
  51. 		window = new MenuWindow("体育娱乐之窗", 100, 100);
  52. 		button.addActionListener(this);
  53. 		add(button);
  54. 	}
  55.  
  56. 	public void actionPerformed(ActionEvent e) {
  57. 		if (e.getSource() == button) {
  58. 			if (bflg) {
  59. 				window.setVisible(true);
  60. 				bflg = false;
  61. 				button.setLabel("关闭我的体育娱乐之窗");
  62. 			} else {
  63. 				window.setVisible(false);
  64. 				bflg = true;
  65. 				button.setLabel("打开我的体育娱乐之窗");
  66. 			}
  67. 		}
  68. 	}
  69. }

例6.6小应用程序声明一个用户窗口类和对话框类，用户窗口有两个按钮和两个文本框，当点击某个按钮时，对应的对话框被激活。

  1. import java.applet.*;
  2. import javax.swing.*;
  3. import java.awt.*;
  4. import java.awt.event.*;
  5.  
  6. class MyWindow extends JFrame implements ActionListener {
  7. 	private JButton button1, button2;
  8. 	private static int flg = 0;
  9. 	private static JTextField text1, text2;
  10.  
  11. 	MyWindow(String s)// 窗口内有两个按钮
  12. 	{
  13. 		super(s);
  14. 		Container con = this.getContentPane();
  15. 		con.setLayout(new GridLayout(2, 2));
  16. 		this.setSize(200, 100);
  17. 		this.setLocation(100, 100);
  18. 		button1 = new JButton("选择水果");
  19. 		button2 = new JButton("选择食品");
  20. 		button1.addActionListener(this);
  21. 		button2.addActionListener(this);
  22. 		text1 = new JTextField(20);
  23. 		text2 = new JTextField(20);
  24. 		con.add(button1);
  25. 		con.add(button2);
  26. 		con.add(text1);
  27. 		con.add(text2);
  28. 		this.setVisible(true);
  29. 		this.pack();
  30. 	}
  31.  
  32. 	public static void returnName(String s) {
  33. 		if (flg == 1) {
  34. 			text1.setText("选择的水果是：" + s);
  35. 		} else if (flg == 2) {
  36. 			text2.setText("选择的食品是：" + s);
  37. 		}
  38. 	}
  39.  
  40. 	public void actionPerformed(ActionEvent e) {
  41. 		MyDialog dialog;
  42. 		if (e.getSource() == button1) {
  43. 			dialog = new MyDialog(this, "水果");
  44. 			dialog.setVisible(true);
  45. 			flg = 1;
  46. 		} else if (e.getSource() == button2) {
  47. 			dialog = new MyDialog(this, "食品");
  48. 			dialog.setVisible(true);
  49. 			flg = 2;
  50. 		}
  51. 	}
  52. }
  53.  
  54. class MyDialog extends JDialog implements ActionListener {
  55. 	JLabel title;
  56. 	JTextField text;
  57. 	JButton done;
  58.  
  59. 	MyDialog(JFrame F, String s) {
  60. 		super(F, s, true);
  61. 		Container con = this.getContentPane();
  62. 		title = new JLabel("输入" + s + "名称");
  63. 		text = new JTextField(10);
  64. 		text.setEditable(true);
  65. 		con.setLayout(new FlowLayout());
  66. 		con.setSize(200, 100);
  67. 		setModal(false);
  68. 		done = new JButton("确定");
  69. 		done.addActionListener(this);
  70. 		con.add(title);
  71. 		con.add(text);
  72. 		con.add(done);
  73. 		con.setVisible(true);
  74. 		this.pack();
  75. 	}
  76.  
  77. 	public void actionPerformed(ActionEvent e) {
  78. 		MyWindow.returnName(text.getText());
  79. 		setVisible(false);
  80. 		dispose();
  81. 	}
  82. }
  83.  
  84. public class Example6_6 extends Applet {
  85. 	MyWindow window;
  86. 	MyDialog diaglog;
  87.  
  88. 	public void init()// 程序的主窗口暂没有组件
  89. 	{
  90. 		window = new MyWindow("带对话框窗口");// 创建一个窗口
  91. 	}
  92. }

例6.7应用程序将滚动条作为值的选择。

  1. import javax.swing.*;
  2. import java.awt.*;
  3. import java.awt.event.*;
  4.  
  5. class MyScrollBar extends JScrollBar {
  6. 	public MyScrollBar(int init, int len, int low, int high) {
  7. 		super(JScrollBar.HORIZONTAL, init, len, low, high);
  8. 	}
  9.  
  10. 	public Dimension getPreferredSize() {
  11. 		return new Dimension(125, 20);
  12. 	}
  13. }
  14.  
  15. class MyWindow extends JFrame implements ActionListener, AdjustmentListener {
  16. 	private JButton button;
  17. 	private JTextField text;
  18. 	private boolean barOpened;
  19.  
  20. 	MyWindow(String s) {
  21. 		super(s);
  22. 		MyScrollBar tempBar = new MyScrollBar(10, 10, 0, 255);
  23. 		Container con = this.getContentPane();
  24. 		con.setLayout(new GridLayout(2, 1));
  25. 		this.setSize(200, 100);
  26. 		this.setLocation(100, 100);
  27. 		button = new JButton("开/闭滚动条");
  28. 		button.addActionListener(this);
  29. 		barOpened = false;
  30. 		tempBar.addAdjustmentListener(this);
  31. 		text = new JTextField("滚动条关闭", 20);
  32. 		con.add(button);
  33. 		con.add(text);
  34. 		con.add(tempBar);
  35. 		this.setVisible(true);
  36. 		this.pack();
  37. 	}
  38.  
  39. 	public void actionPerformed(ActionEvent e) {
  40. 		if (e.getSource() == button) {
  41. 			if (barOpened) {
  42. 				text.setText("滚动条关闭");
  43. 			} else {
  44. 				text.setText("滚动条打开");
  45. 			}
  46. 			barOpened = !barOpened;
  47. 		}
  48. 	}
  49.  
  50. 	public void adjustmentValueChanged(AdjustmentEvent e) {
  51. 		if (barOpened) {
  52. 			MyScrollBar myBar = (MyScrollBar) e.getAdjustable();
  53. 			text.setText("选择的值是：" + myBar.getValue());
  54. 		}
  55. 	}
  56. }
  57.  
  58. public class Example6_7 {
  59. 	public static void main(String[] args) {
  60. 		MyWindow myWindow = new MyWindow("滚动条实例");
  61. 	}
  62. }

例6.8小应用程序设置了一个文本区，用于记录一系列鼠标事件。

  1. import java.applet.*;
  2. import java.awt.*;
  3. import javax.swing.*;
  4. import java.awt.event.*;
  5.  
  6. class MyPanel extends JPanel {
  7. 	public void print(int r) {
  8. 		Graphics g = getGraphics();// 获得系统给予小应用程序的图形对象
  9. 		g.clearRect(0, 0, this.getWidth(), this.getHeight());
  10. 		g.setColor(Color.red);
  11. 		g.fillOval(10, 10, r, r);// 用红色填充一个圆块
  12. 	}
  13. }
  14.  
  15. class MyWindow extends JFrame implements MouseListener {
  16. 	JTextArea text;
  17. 	MyPanel panel;
  18. 	int x, y, r = 10;
  19. 	int mouseFlg = 0;
  20. 	static String mouseStates[] = { "鼠标键按下", "鼠标松开", "鼠标进来", "鼠标走开", "鼠标双击" };
  21.  
  22. 	MyWindow(String s) {
  23. 		super(s);
  24. 		Container con = this.getContentPane();
  25. 		con.setLayout(new GridLayout(2, 1));
  26. 		this.setSize(200, 300);
  27. 		this.setLocation(100, 100);
  28. 		panel = new MyPanel();
  29. 		con.add(panel);
  30. 		text = new JTextArea(10, 20);
  31. 		text.setBackground(Color.blue);
  32. 		con.add(text);
  33. 		addMouseListener(this);
  34. 		this.setVisible(true);
  35. 		this.pack();
  36. 	}
  37.  
  38. 	public void paint(Graphics g) {
  39. 		r = r + 4;
  40. 		if (r > 80) {
  41. 			r = 10;
  42. 		}
  43. 		text.append(mouseStates[mouseFlg] + "了，位置是：" + x + "," + y + "\n");
  44. 		panel.print(r);
  45. 	}
  46.  
  47. 	public void mousePressed(MouseEvent e) {
  48. 		x = e.getX();
  49. 		y = e.getY();
  50. 		mouseFlg = 0;
  51. 		repaint();
  52. 	}
  53.  
  54. 	public void mouseReleased(MouseEvent e) {
  55. 		x = e.getX();
  56. 		y = e.getY();
  57. 		mouseFlg = 1;
  58. 		repaint();
  59. 	}
  60.  
  61. 	public void mouseEntered(MouseEvent e) {
  62. 		x = e.getX();
  63. 		y = e.getY();
  64. 		mouseFlg = 2;
  65. 		repaint();
  66. 	}
  67.  
  68. 	public void mouseExited(MouseEvent e) {
  69. 		x = e.getX();
  70. 		y = e.getY();
  71. 		mouseFlg = 3;
  72. 		repaint();
  73. 	}
  74.  
  75. 	public void mouseClicked(MouseEvent e) {
  76. 		if (e.getClickCount() == 2) {
  77. 			x = e.getX();
  78. 			y = e.getY();
  79. 			mouseFlg = 4;
  80. 			repaint();
  81. 		} else {
  82.  
  83. 		}
  84. 	}
  85. }
  86.  
  87. public class Example6_8 extends Applet {
  88. 	public void init() {
  89. 		MyWindow myWindow = new MyWindow("鼠标事件示意程序");
  90. 	}
  91. }

例6.9一个滚动条与显示窗口同步变化的应用程序。

  1. import java.awt.*;
  2. import javax.swing.*;
  3. import java.awt.event.*;
  4.  
  5. class MyWindow extends JFrame {
  6. 	public MyWindow(String s) {
  7. 		super(s);
  8. 		Container con = this.getContentPane();
  9. 		con.setLayout(new GridLayout());
  10. 		this.setLocation(100, 100);
  11. 		JScrollBar xAxis = new JScrollBar(JScrollBar.HORIZONTAL, 50, 1, 0, 100);
  12. 		JScrollBar yAxis = new JScrollBar(JScrollBar.VERTICAL, 50, 1, 0, 100);
  13. 		MyListener listener = new MyListener(xAxis, yAxis, 238, 118);
  14. 		JPanel scrolledCanvas = new JPanel();
  15. 		scrolledCanvas.setLayout(new BorderLayout());
  16. 		scrolledCanvas.add(listener, BorderLayout.CENTER);
  17. 		scrolledCanvas.add(xAxis, BorderLayout.SOUTH);
  18. 		scrolledCanvas.add(yAxis, BorderLayout.EAST);
  19. 		con.add(scrolledCanvas, BorderLayout.CENTER);
  20. 		this.setVisible(true);
  21. 		this.pack();
  22. 	}
  23.  
  24. 	public Dimension getPreferredSize() {
  25. 		return new Dimension(500, 300);
  26. 	}
  27. }
  28.  
  29. class MyListener extends JComponent implements MouseListener, MouseMotionListener, AdjustmentListener {
  30. 	private int x, y;
  31. 	private JScrollBar xScrollBar;
  32. 	private JScrollBar yScrollBar;
  33.  
  34. 	private void updateScrollBars(int x, int y) {
  35. 		int d;
  36. 		d = (int) (((float) x / (float) getSize().width) * 100.0);
  37. 		xScrollBar.setValue(d);
  38. 		d = (int) (((float) y / (float) getSize().height) * 100.0);
  39. 		yScrollBar.setValue(d);
  40. 	}
  41.  
  42. 	public MyListener(JScrollBar xaxis, JScrollBar yaxis, int x0, int y0) {
  43. 		xScrollBar = xaxis;
  44. 		yScrollBar = yaxis;
  45. 		x = x0;
  46. 		y = y0;
  47. 		xScrollBar.addAdjustmentListener(this);
  48. 		yScrollBar.addAdjustmentListener(this);
  49. 		this.addMouseListener(this);// 监视鼠标点击事件
  50. 		this.addMouseMotionListener(this);// 监视鼠标拖动事件
  51. 	}
  52.  
  53. 	public void paint(Graphics g) {
  54. 		g.setColor(getBackground());
  55. 		Dimension size = getSize();
  56. 		g.fillRect(0, 0, size.width, size.height);
  57. 		g.setColor(Color.blue);
  58. 		g.fillRect(x, y, 50, 50);
  59. 	}
  60.  
  61. 	public void mouseEntered(MouseEvent e) {
  62.  
  63. 	}
  64.  
  65. 	public void mouseExited(MouseEvent e) {
  66.  
  67. 	}
  68.  
  69. 	public void mouseClicked(MouseEvent e) {
  70.  
  71. 	}
  72.  
  73. 	public void mouseReleased(MouseEvent e) {
  74.  
  75. 	}
  76.  
  77. 	public void mouseMoved(MouseEvent e) {
  78.  
  79. 	}
  80.  
  81. 	public void mousePressed(MouseEvent e) {
  82. 		x = e.getX();
  83. 		y = e.getY();
  84. 		updateScrollBars(x, y);
  85. 		repaint();
  86. 	}
  87.  
  88. 	public void mouseDragged(MouseEvent e) {
  89. 		x = e.getX();
  90. 		y = e.getY();
  91. 		updateScrollBars(x, y);
  92. 		repaint();
  93. 	}
  94.  
  95. 	public void adjustmentValueChanged(AdjustmentEvent e) {
  96. 		if (e.getSource() == xScrollBar) {
  97. 			x = (int) ((float) (xScrollBar.getValue() / 100.0) * getSize().width);
  98. 		} else if (e.getSource() == yScrollBar) {
  99. 			y = (int) ((float) (yScrollBar.getValue() / 100.0) * getSize().height);
  100. 		}
  101. 		repaint();
  102. 	}
  103. }
  104.  
  105. public class Example6_9 {
  106. 	public static void main(String[] args) {
  107. 		MyWindow myWindow = new MyWindow("滚动条示意程序");
  108. 	}
  109. }

例6.10小应用程序有一个按钮和一个文本区，按钮作为发生键盘事件的事件源，并对它实施监视。

  1. import java.applet.*;
  2. import java.awt.*;
  3. import java.awt.event.*;
  4.  
  5. public class Example6_10 extends Applet implements KeyListener {
  6. 	int count = 0;
  7. 	Button button = new Button();
  8. 	TextArea text = new TextArea(5, 20);
  9.  
  10. 	public void init() {
  11. 		button.addKeyListener(this);
  12. 		add(button);
  13. 		add(text);
  14. 	}
  15.  
  16. 	public void keyPressed(KeyEvent e) {
  17. 		int t = e.getKeyCode();
  18. 		if (t >= KeyEvent.VK_A && t <= KeyEvent.VK_Z) {
  19. 			text.append((char) t + " ");
  20. 			count++;
  21. 			if (count % 10 == 0) {
  22. 				text.append("\n");
  23. 			}
  24. 		}
  25. 	}
  26.  
  27. 	public void keyTyped(KeyEvent e) {
  28.  
  29. 	}
  30.  
  31. 	public void keyReleased(KeyEvent e) {
  32.  
  33. 	}
  34. }

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