dialogdemo.java

这是一个用java编写的关于GUI应用编程的简单的样例

                                    "Eggs aren't supposed to be green.",
                                    "A plain message",
                                    JOptionPane.PLAIN_MESSAGE);
                //information icon
                } else if (command == infoCommand) {
                    JOptionPane.showMessageDialog(frame,
                                    "Eggs aren't supposed to be green.",
                                    "Inane informational dialog",
                                    JOptionPane.INFORMATION_MESSAGE);

            //XXX: It doesn't make sense to make a question with
            //XXX: only one button.
            //XXX: See "Yes/No (but not in those words)" for a better solution.
                //question icon
                } else if (command == questionCommand) {
                    JOptionPane.showMessageDialog(frame,
                                    "You shouldn't use a message dialog "
                                    + "(like this)\n"
                                    + "for a question, OK?",
                                    "Inane question",
                                    JOptionPane.QUESTION_MESSAGE);
                //error icon
                } else if (command == errorCommand) {
                    JOptionPane.showMessageDialog(frame,
                                    "Eggs aren't supposed to be green.",
                                    "Inane error",
                                    JOptionPane.ERROR_MESSAGE);
                //warning icon
                } else if (command == warningCommand) {
                    JOptionPane.showMessageDialog(frame,
                                    "Eggs aren't supposed to be green.",
                                    "Inane warning",
                                    JOptionPane.WARNING_MESSAGE);
                //custom icon
                } else if (command == customCommand) {
                    JOptionPane.showMessageDialog(frame,
                                    "Eggs aren't supposed to be green.",
                                    "Inane custom dialog",
                                    JOptionPane.INFORMATION_MESSAGE,
                                    icon);
                }
            }
        });

        return create2ColPane(iconDesc + ":",
                              radioButtons,
                              showItButton);
    }

    /** Creates the panel shown by the second tab. */
    private JPanel createFeatureDialogBox() {
        final int numButtons = 5;
        JRadioButton[] radioButtons = new JRadioButton[numButtons];
        final ButtonGroup group = new ButtonGroup();

        JButton showItButton = null;

        final String pickOneCommand = "pickone";
        final String textEnteredCommand = "textfield";
        final String nonAutoCommand = "nonautooption";
        final String customOptionCommand = "customoption";
        final String nonModalCommand = "nonmodal";

        radioButtons[0] = new JRadioButton("Pick one of several choices");
        radioButtons[0].setActionCommand(pickOneCommand);

        radioButtons[1] = new JRadioButton("Enter some text");
        radioButtons[1].setActionCommand(textEnteredCommand);

        radioButtons[2] = new JRadioButton("Non-auto-closing dialog");
        radioButtons[2].setActionCommand(nonAutoCommand);

        radioButtons[3] = new JRadioButton("Input-validating dialog "
                                           + "(with custom message area)");
        radioButtons[3].setActionCommand(customOptionCommand);

        radioButtons[4] = new JRadioButton("Non-modal dialog");
        radioButtons[4].setActionCommand(nonModalCommand);

        for (int i = 0; i < numButtons; i++) {
            group.add(radioButtons[i]);
        }
        radioButtons[0].setSelected(true);

        showItButton = new JButton("Show it!");
        showItButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String command = group.getSelection().getActionCommand();

                //pick one of many
                if (command == pickOneCommand) {
                    Object[] possibilities = {"ham", "spam", "yam"};
                    String s = (String)JOptionPane.showInputDialog(
                                        frame,
                                        "Complete the sentence:\n"
                                        + "\"Green eggs and...\"",
                                        "Customized Dialog",
                                        JOptionPane.PLAIN_MESSAGE,
                                        icon,
                                        possibilities,
                                        "ham");

                    //If a string was returned, say so.
                    if ((s != null) && (s.length() > 0)) {
                        setLabel("Green eggs and... " + s + "!");
                        return;
                    }

                    //If you're here, the return value was null/empty.
                    setLabel("Come on, finish the sentence!");

                //text input
                } else if (command == textEnteredCommand) {
                    String s = (String)JOptionPane.showInputDialog(
                                        frame,
                                        "Complete the sentence:\n"
                                        + "\"Green eggs and...\"",
                                        "Customized Dialog",
                                        JOptionPane.PLAIN_MESSAGE,
                                        icon,
                                        null,
                                        "ham");

                    //If a string was returned, say so.
                    if ((s != null) && (s.length() > 0)) {
                        setLabel("Green eggs and... " + s + "!");
                        return;
                    }

                    //If you're here, the return value was null/empty.
                    setLabel("Come on, finish the sentence!");

                //non-auto-closing dialog
                } else if (command == nonAutoCommand) {
                    final JOptionPane optionPane = new JOptionPane(
                                    "The only way to close this dialog is by\n"
                                    + "pressing one of the following buttons.\n"
                                    + "Do you understand?",
                                    JOptionPane.QUESTION_MESSAGE,
                                    JOptionPane.YES_NO_OPTION);

                    //HACK used to get a close button.  This dialog
                    //illustrates the questionable practice of not
                    //letting someone close the window using the
                    //window decoration.  Since the Java Look and Feel
                    //doesn't decorate its dialogs with a close button,
                    //we must turn on system window decorations in hopes
                    //of getting a close button.
                    JDialog.setDefaultLookAndFeelDecorated(false);

                    //You can't use pane.createDialog() because that
                    //method sets up the JDialog with a property change
                    //listener that automatically closes the window
                    //when a button is clicked.
                    final JDialog dialog = new JDialog(frame,
                                                 "Click a button",
                                                 true);
                    dialog.setContentPane(optionPane);
                    dialog.setDefaultCloseOperation(
                        JDialog.DO_NOTHING_ON_CLOSE);
                    dialog.addWindowListener(new WindowAdapter() {
                        public void windowClosing(WindowEvent we) {
                            setLabel("Thwarted user attempt to close window.");
                        }
                    });
                    //Undo the hack!
                    JDialog.setDefaultLookAndFeelDecorated(true);

                    optionPane.addPropertyChangeListener(
                        new PropertyChangeListener() {
                            public void propertyChange(PropertyChangeEvent e) {
                                String prop = e.getPropertyName();

                                if (dialog.isVisible()
                                 && (e.getSource() == optionPane)
                                 && (JOptionPane.VALUE_PROPERTY.equals(prop))) {
                                    //If you were going to check something
                                    //before closing the window, you'd do
                                    //it here.
                                    dialog.setVisible(false);
                                }
                            }
                        });
                    dialog.pack();
                    dialog.setLocationRelativeTo(frame);
                    dialog.setVisible(true);

                    int value = ((Integer)optionPane.getValue()).intValue();
                    if (value == JOptionPane.YES_OPTION) {
                        setLabel("Good.");
                    } else if (value == JOptionPane.NO_OPTION) {
                        setLabel("Try using the window decorations "
                                 + "to close the non-auto-closing dialog. "
                                 + "You can't!");
                    } else {
                        setLabel("Window unavoidably closed (ESC?).");
                    }

                //non-auto-closing dialog with custom message area
                //NOTE: if you don't intend to check the input,
                //then just use showInputDialog instead.
                } else if (command == customOptionCommand) {
                    customDialog.setLocationRelativeTo(frame);
                    customDialog.setVisible(true);

                    String s = customDialog.getValidatedText();
                    if (s != null) {
                        //The text is valid.
                        setLabel("Congratulations!  "
                                 + "You entered \""
                                 + s
                                 + "\".");
                    }

                //non-modal dialog
                } else if (command == nonModalCommand) {
                    //Create the dialog.
                    final JDialog dialog = new JDialog(frame,
                                                       "A Non-Modal Dialog");

                    //Add contents to it. It must have a close button,
                    //since some L&Fs (notably Java/Metal) don't provide one
                    //in the window decorations for dialogs.
                    JLabel label = new JLabel("<html><p align=center>"
                        + "This is a non-modal dialog.<br>"
                        + "You can have one or more of these up<br>"
                        + "and still use the main window.");
                    label.setHorizontalAlignment(JLabel.CENTER);
                    Font font = label.getFont();
                    label.setFont(label.getFont().deriveFont(font.PLAIN,
                                                             14.0f));

                    JButton closeButton = new JButton("Close");
                    closeButton.addActionListener(new ActionListener() {
                        public void actionPerformed(ActionEvent e) {
                            dialog.setVisible(false);
                            dialog.dispose();
                        }
                    });
                    JPanel closePanel = new JPanel();
                    closePanel.setLayout(new BoxLayout(closePanel,
                                                       BoxLayout.LINE_AXIS));
                    closePanel.add(Box.createHorizontalGlue());
                    closePanel.add(closeButton);
                    closePanel.setBorder(BorderFactory.
                        createEmptyBorder(0,0,5,5));

                    JPanel contentPane = new JPanel(new BorderLayout());
                    contentPane.add(label, BorderLayout.CENTER);
                    contentPane.add(closePanel, BorderLayout.PAGE_END);
                    contentPane.setOpaque(true);
                    dialog.setContentPane(contentPane);

                    //Show it.
                    dialog.setSize(new Dimension(300, 150));
                    dialog.setLocationRelativeTo(frame);
                    dialog.setVisible(true);
                }
            }
        });

        return createPane(moreDialogDesc + ":",
                          radioButtons,
                          showItButton);
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        JFrame frame = new JFrame("DialogDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Create and set up the content pane.
        DialogDemo newContentPane = new DialogDemo(frame);
        newContentPane.setOpaque(true); //content panes must be opaque
        frame.setContentPane(newContentPane);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }

}