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Chapter 12

Chapter 12. Graphical User Interfaces. Figure 1 A Program with Four Buttons. Use Panels to Organize Buttons. JPanel buttonPanel = new JPanel(); buttonPanel.add(upButton); buttonPanel.add(downButton); . . . contentPane.add(buttonPanel, "South");. Figure 2 Containers with

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Chapter 12

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  1. Chapter 12 Graphical User Interfaces

  2. Figure 1 A Program with Four Buttons

  3. Use Panels to Organize Buttons • JPanel buttonPanel = new JPanel(); • buttonPanel.add(upButton);buttonPanel.add(downButton);. . . • contentPane.add(buttonPanel, "South");

  4. Figure 2 Containers with Separate Layout Managers

  5. Layout Managers • BorderLayout (center, south, north, east, west) • FlowLayout (left-to-right) • GridLayout (rectangular grid) • Default: Content pane has border layout • Default: Panels have flow layout • Change default: panel.setLayout(new GridLayout(4, 3));

  6. Figure 3 The Border Layout Grows Components

  7. FlowLayout doesn't grow content • The border layout and grid layout grow buttons etc. to fit the entire area of the border or grid • Remedy: put button(s) inside panel with flow layout

  8. Figure 4 Grid Layout

  9. Grid Layout • Add buttons left-to-right/top-to-bottompanel.add(button7);panel.add(button8);panel.add(button9);panel.add(button4);. . .panel.add(buttonCE);

  10. Figure 5 Buttons with Labels and Icons

  11. Buttons • Specify label and optional icon in constructorJButton leftButton = new JButton("left");leftButton = new JButton("left", new ImageIcon("left.gif")); • Add action listener to handle “button click” event

  12. Program ButtonTest.java import java.awt.Container; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Rectangle; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; public class ButtonTest { public static void main(String[] args) { ButtonFrame frame = new ButtonFrame(); frame.setTitle("ButtonTest"); frame.show();

  13. } } class ButtonFrame extends JFrame { public ButtonFrame() { final int DEFAULT_FRAME_WIDTH = 300; final int DEFAULT_FRAME_HEIGHT = 300; setSize(DEFAULT_FRAME_WIDTH,DEFAULT_FRAME_HEIGHT); addWindowListener(new WindowCloser()); // construct components panel = new RectanglePanel(); JPanel buttonPanel = new JPanel(); ActionListener listener = new DirectionListener(); upButton = new JButton("Up"); upButton.addActionListener(listener);

  14. downButton = new JButton("Down"); downButton.addActionListener(listener); leftButton = new JButton("Left"); leftButton.addActionListener(listener); rightButton = new JButton("Right"); rightButton.addActionListener(listener); // add components to content pane Container contentPane = getContentPane(); contentPane.add(panel, "Center"); buttonPanel.add(upButton); buttonPanel.add(downButton); buttonPanel.add(leftButton); buttonPanel.add(rightButton);

  15. contentPane.add(buttonPanel, "South"); } private RectanglePanel panel; private JButton upButton; private JButton downButton; private JButton leftButton; private JButton rightButton; // inner class definition private class DirectionListener implements ActionListener { public void actionPerformed(ActionEvent event) { // find the button that was clicked Object source = event.getSource();

  16. if (source == upButton) panel.moveRectangle(0, -1); else if (source == downButton) panel.moveRectangle(0, 1); else if (source == leftButton) panel.moveRectangle(-1, 0); else if (source == rightButton) panel.moveRectangle(1, 0); } } private class WindowCloser extends WindowAdapter { public void windowClosing(WindowEvent event) { System.exit(0); } } }

  17. class RectanglePanel extends JPanel { public RectanglePanel() { rect = new Rectangle(0, 0, RECT_WIDTH, RECT_HEIGHT); } public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2 = (Graphics2D)g; g2.draw(rect); }

  18. /** Moves the rectangle and repaints it. The rectangle is moved by multiples of its full width or height. @param dx the number of width units @param dy the number of height units */ public void moveRectangle(int dx, int dy) { rect.translate(dx * RECT_WIDTH, dy * RECT_HEIGHT); repaint(); } private Rectangle rect; private static final int RECT_WIDTH = 20; private static final int RECT_HEIGHT = 30; }

  19. Figure 6 A Frame with a Text Area and a Text Field

  20. Text Components • Specify number of rows/characters in constructor:tf = new TextField(5);ta = new TextArea(10, 40); • Turn edit mode off if you want to display textta.setEditable(false); • Set text programmaticallytf.setText("Hello");

  21. Labels • Use a label to tag a text fieldJLabel label = new JLabel("Name", SwingConstants.RIGHT); • Add label to panel: panel.add(label);panel.add(nameField);

  22. Program TextTest.java import java.awt.Container; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.util.StringTokenizer; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JTextArea; import javax.swing.JTextField; public class TextTest { public static void main(String[] args) { TextFrame frame = new TextFrame();

  23. frame.setTitle("TextTest"); frame.show(); } } class TextFrame extends JFrame { public TextFrame() { final int DEFAULT_FRAME_WIDTH = 300; final int DEFAULT_FRAME_HEIGHT = 300; setSize(DEFAULT_FRAME_WIDTH, DEFAULT_FRAME_HEIGHT); addWindowListener(new WindowCloser()); // construct components inputArea = new JTextArea(); resultField = new JTextField(20); resultField.setEditable(false);

  24. calcButton = new JButton("Calculate"); calcButton.addActionListener(new ButtonListener()); // add components to content pane Container contentPane = getContentPane(); contentPane.add(inputArea, "Center"); // arrange the label and text field in a panel JPanel resultPanel = new JPanel(); resultPanel.add(new JLabel("Average:")); resultPanel.add(resultField); // place the button in a panel JPanel buttonPanel = new JPanel(); buttonPanel.add(calcButton); // stack up these two panels in another panel

  25. JPanel southPanel = new JPanel(); southPanel.setLayout(new GridLayout(2, 1)); southPanel.add(resultPanel); southPanel.add(buttonPanel); contentPane.add(southPanel, "South"); } /** Reads numbers from a string that contains a sequence of floating-point numbers separated by white space. @param input the string containing the numbers @return the numbers that were found in the string */ public static double[] getData(String input) { StringTokenizer tokenizer = new StringTokenizer(input); double[] data = new double[tokenizer.countTokens()]; for (int i = 0; i < data.length; i++) data[i] = Double.parseDouble(tokenizer.nextToken()); return data;

  26. } /** Computes the average of an array of floating-point numbers. @param data the numbers to average @return the average, or 0 if the array was empty */ public static double average(double[] data) { if (data.length == 0) return 0; double sum = 0; for (int i = 0; i < data.length; i++) sum = sum + data[i]; return sum / data.length; } private JTextArea inputArea; private JTextField resultField; private JButton calcButton;

  27. private class ButtonListener implements ActionListener { public void actionPerformed(ActionEvent event) { // get user input from text area double[] data = getData(inputArea.getText()); // compute average and display in result field double avg = average(data); resultField.setText("” + avg); } } private class WindowCloser extends WindowAdapter { public void windowClosing(WindowEvent event) { System.exit(0); } } }

  28. Figure 7 A Combo Box, Radio Buttons, and Check Boxes

  29. Radio Buttons • Radio buttons are mutually exclusive • Button group turns one button off when the next one is turned onsButton = new JRadioButton("Small");mButton = new JRadioButton("Medium"); lButton = new JRadioButton("Large");buttonGroup.add(sbutton);buttonGroup.add(mbutton);buttonGroup.add(lbutton) • Still need to add to panel

  30. Check Boxes • Similar to radio button, not mutually exclusiveJCheckBox it = new JCheckBox("Italic"); • Test if selectedif (it.isSelected()) . . .

  31. Borders • Use border to group related components • Add border to panel holding components • panel.setBorder(new TitledBorder(new EtchedBorder(), "Title"));

  32. Figure 8 An Opened Combo Box

  33. Combo boxes • Use less space than radio buttons • Users can type other values • “Combo” between list selection and text field • JComboBox faceName = new JComboBox();faceName.addItem("Serif");faceName.addItem("SansSerif");. . . • Get user selectionsel= (String)faceName.getSelectedItem();

  34. Program ChoiceTest.java import java.awt.Container; import java.awt.Font; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.swing.ButtonGroup; import javax.swing.JButton; import javax.swing.JCheckBox; import javax.swing.JComboBox; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JRadioButton; import javax.swing.JTextField; import javax.swing.border.EtchedBorder; import javax.swing.border.TitledBorder;

  35. public class ChoiceTest { public static void main(String[] args) { ChoiceFrame frame = new ChoiceFrame(); frame.setTitle("ChoiceTest"); frame.show(); } } class ChoiceFrame extends JFrame { public ChoiceFrame() { final int DEFAULT_FRAME_WIDTH = 300; final int DEFAULT_FRAME_HEIGHT = 300; setSize(DEFAULT_FRAME_WIDTH, DEFAULT_FRAME_HEIGHT); addWindowListener(new WindowCloser()); // construct components

  36. sampleField = new JTextField ("Computing Concepts with Java Essentials"); sampleField.setEditable(false); ChoiceListener listener = new ChoiceListener(); facenameCombo = new JComboBox(); facenameCombo.addItem("Serif"); facenameCombo.addItem("SansSerif"); facenameCombo.addItem("Monospaced"); facenameCombo.setEditable(true); facenameCombo.addActionListener(listener); italicCheckBox = new JCheckBox("Italic"); italicCheckBox.addActionListener(listener); boldCheckBox = new JCheckBox("Bold"); boldCheckBox.addActionListener(listener);

  37. smallButton = new JRadioButton("Small"); smallButton.setSelected(true); smallButton.addActionListener(listener); mediumButton = new JRadioButton("Medium"); mediumButton.addActionListener(listener); largeButton = new JRadioButton("Large"); largeButton.addActionListener(listener); // add radio buttons to button group ButtonGroup sizeGroup = new ButtonGroup(); sizeGroup.add(smallButton); sizeGroup.add(mediumButton); sizeGroup.add(largeButton);

  38. // add components to panels JPanel facenamePanel = new JPanel(); facenamePanel.add(facenameCombo); JPanel sizeGroupPanel = new JPanel(); sizeGroupPanel.add(smallButton); sizeGroupPanel.add(mediumButton); sizeGroupPanel.add(largeButton); sizeGroupPanel.setBorder (new TitledBorder(new EtchedBorder(), "Size")); JPanel styleGroupPanel = new JPanel(); styleGroupPanel.add(italicCheckBox); styleGroupPanel.add(boldCheckBox); styleGroupPanel.setBorder (new TitledBorder(new EtchedBorder(), "Style")); // line up component panels

  39. JPanel southPanel = new JPanel(); southPanel.setLayout(new GridLayout(3, 1)); southPanel.add(facenamePanel); southPanel.add(sizeGroupPanel); southPanel.add(styleGroupPanel); // add panels to content pane Container contentPane = getContentPane(); contentPane.add(sampleField, "Center"); contentPane.add(southPanel, "South"); setSampleFont(); } /** Gets user choice for font name, style, and size and sets the font of the text field. */

  40. public void setSampleFont() { // get font name String facename = (String)facenameCombo.getSelectedItem(); // get font style int style = 0; if (italicCheckBox.isSelected()) style = style + Font.ITALIC; if (boldCheckBox.isSelected()) style = style + Font.BOLD; // get font size final int SMALL_SIZE = 12; final int MEDIUM_SIZE = 16; final int LARGE_SIZE = 24;

  41. int size = 0; if (smallButton.isSelected()) size = SMALL_SIZE; else if (mediumButton.isSelected()) size = MEDIUM_SIZE; else if (largeButton.isSelected()) size = LARGE_SIZE; // set font of text field sampleField.setFont(new Font(facename, style, size)); sampleField.repaint(); }

  42. private JTextField sampleField; private JCheckBox italicCheckBox; private JCheckBox boldCheckBox; private JRadioButton smallButton; private JRadioButton mediumButton; private JRadioButton largeButton; private JComboBox facenameCombo; private class ChoiceListener implements ActionListener { public void actionPerformed(ActionEvent event) { setSampleFont(); } } private class WindowCloser extends WindowAdapter { public void windowClosing(WindowEvent event) { System.exit(0); } } }

  43. Figure 9 Pulldown Menus

  44. Menus • Add menu bar to frameJMenuBar bar = new JMenuBar();frame.setJMenuBar(bar); • Add menus to the menu barJMenu fileMenu = new JMenu("File");bar.add(fileMenu);

  45. Menu items • Add menu items to the menuJMenuItem fileNew = new JMenuItem("New"); • Add action listener to the menu itemActionListener l = ...;fileNew.addActionListener(l);

  46. Program MenuTest.java import java.awt.Container; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Rectangle; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.util.Random; import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.JPanel;

  47. public class MenuTest { public static void main(String[] args) { MenuFrame frame = new MenuFrame(); frame.setTitle("MenuTest"); frame.show(); } } class MenuFrame extends JFrame { public MenuFrame() { final int DEFAULT_FRAME_WIDTH = 300; final int DEFAULT_FRAME_HEIGHT = 300; setSize(DEFAULT_FRAME_WIDTH, DEFAULT_FRAME_HEIGHT); addWindowListener(new WindowCloser()); // add drawing panel to content pane

  48. panel = new RectanglePanel(); Container contentPane = getContentPane(); contentPane.add(panel, "Center"); // construct menu JMenuBar menuBar = new JMenuBar(); setJMenuBar(menuBar); JMenu fileMenu = new JMenu("File"); menuBar.add(fileMenu); MenuListener listener = new MenuListener(); newMenuItem = new JMenuItem("New"); fileMenu.add(newMenuItem); newMenuItem.addActionListener(listener);

  49. exitMenuItem = new JMenuItem("Exit"); fileMenu.add(exitMenuItem); exitMenuItem.addActionListener(listener); JMenu editMenu = new JMenu("Edit"); menuBar.add(editMenu); JMenuItem moveMenu = new JMenu("Move"); editMenu.add(moveMenu); upMenuItem = new JMenuItem("Up"); moveMenu.add(upMenuItem); upMenuItem.addActionListener(listener); downMenuItem = new JMenuItem("Down"); moveMenu.add(downMenuItem); downMenuItem.addActionListener(listener);

  50. leftMenuItem = new JMenuItem("Left"); moveMenu.add(leftMenuItem); leftMenuItem.addActionListener(listener); rightMenuItem = new JMenuItem("Right"); moveMenu.add(rightMenuItem); rightMenuItem.addActionListener(listener); randomizeMenuItem = new JMenuItem("Randomize"); editMenu.add(randomizeMenuItem); randomizeMenuItem.addActionListener(listener); } private JMenuItem exitMenuItem; private JMenuItem newMenuItem; private JMenuItem upMenuItem; private JMenuItem downMenuItem; private JMenuItem leftMenuItem; private JMenuItem rightMenuItem;

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