listdialog.java

这是一个英文版的《Java程序设计与问题解决》现在好多大学都当成教材

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

/*
 * ListDialog.java is a 1.4 class meant to be used by programs such as
 * ListDialogRunner.  It requires no additional files.
 */

/**
 * Use this modal dialog to let the user choose one string from a long
 * list.  See ListDialogRunner.java for an example of using ListDialog.
 * The basics:
 * <pre>
    String[] choices = {"A", "long", "array", "of", "strings"};
    String selectedName = ListDialog.showDialog(
                                componentInControllingFrame,
                                locatorComponent,
                                "A description of the list:",
                                "Dialog Title",
                                choices,
                                choices[0]);
 * </pre>
 */
public class ListDialog extends JDialog
                        implements ActionListener {
    private static ListDialog dialog;
    private static String value = "";
    private JList list;

    /**
     * Set up and show the dialog.  The first Component argument
     * determines which frame the dialog depends on; it should be
     * a component in the dialog's controlling frame. The second
     * Component argument should be null if you want the dialog
     * to come up with its left corner in the center of the screen;
     * otherwise, it should be the component on top of which the
     * dialog should appear.
     */
    public static String showDialog(Component frameComp,
                                    Component locationComp,
                                    String labelText,
                                    String title,
                                    String[] possibleValues,
                                    String initialValue) {
        Frame frame = JOptionPane.getFrameForComponent(frameComp);
        dialog = new ListDialog(frame,
                                locationComp,
                                labelText,
                                title,
                                possibleValues,
                                initialValue);
        dialog.setVisible(true);
        return value;
    }

    private void setValue(String newValue) {
        value = newValue;
        list.setSelectedValue(value, true);
    }

    private ListDialog(Frame frame,
                       Component locationComp,
                       String labelText,
                       String title,
                       Object[] data,
                       String initialValue) {
        super(frame, title, true);

        //Create and initialize the buttons.
        JButton cancelButton = new JButton("Cancel");
        cancelButton.addActionListener(this);
        //
        final JButton setButton = new JButton("Set");
        setButton.setActionCommand("Set");
        setButton.addActionListener(this);
        getRootPane().setDefaultButton(setButton);

        //main part of the dialog
        list = new JList(data);
        list.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
        list.addMouseListener(new MouseAdapter() {
            public void mouseClicked(MouseEvent e) {
                if (e.getClickCount() == 2) {
                    setButton.doClick(); //emulate button click
                }
            }
        });
        JScrollPane listScroller = new JScrollPane(list);
        listScroller.setPreferredSize(new Dimension(250, 80));
        //XXX: Must do the following, too, or else the scroller thinks
        //XXX: it's taller than it is:
        listScroller.setMinimumSize(new Dimension(250, 80));
        listScroller.setAlignmentX(LEFT_ALIGNMENT);

        //Create a container so that we can add a title around
        //the scroll pane.  Can't add a title directly to the
        //scroll pane because its background would be white.
        //Lay out the label and scroll pane from top to button.
        JPanel listPane = new JPanel();
        listPane.setLayout(new BoxLayout(listPane, BoxLayout.Y_AXIS));
        JLabel label = new JLabel(labelText);
        label.setLabelFor(list);
        listPane.add(label);
        listPane.add(Box.createRigidArea(new Dimension(0,5)));
        listPane.add(listScroller);
        listPane.setBorder(BorderFactory.createEmptyBorder(10,10,10,10));

        //Lay out the buttons from left to right.
        JPanel buttonPane = new JPanel();
        buttonPane.setLayout(new BoxLayout(buttonPane, BoxLayout.X_AXIS));
        buttonPane.setBorder(BorderFactory.createEmptyBorder(0, 10, 10, 10));
        buttonPane.add(Box.createHorizontalGlue());
        buttonPane.add(cancelButton);
        buttonPane.add(Box.createRigidArea(new Dimension(10, 0)));
        buttonPane.add(setButton);

        //Put everything together, using the content pane's BorderLayout.
        Container contentPane = getContentPane();
        contentPane.add(listPane, BorderLayout.CENTER);
        contentPane.add(buttonPane, BorderLayout.PAGE_END);

        //Initialize values.
        setValue(initialValue);
        pack();
        setLocationRelativeTo(locationComp);
    }

    //Handle clicks on the Set and Cancel buttons.
    public void actionPerformed(ActionEvent e) {
        if ("Set".equals(e.getActionCommand())) {
            ListDialog.value = (String)(list.getSelectedValue());
        }
        ListDialog.dialog.setVisible(false);
    }
}