Java SplitPaneDemo 不起作用？

Question

我正在尝试从 java 官方网站启动并运行此代码，但我得到

Exception in thread "AWT-EventQueue-0" java.lang.StackOverflowError
    at sun.awt.Win32GraphicsConfig.getBounds(Native Method)
    at sun.awt.Win32GraphicsConfig.getBounds(Unknown Source)
    at java.awt.Window.init(Unknown Source)
    at java.awt.Window.<init>(Unknown Source)
    at java.awt.Frame.<init>(Unknown Source)
    at javax.swing.JFrame.<init>(Unknown Source)

http://download.oracle.com/javase/tutorial/uiswing/examples/components/SplitPaneDemo2Project/src/components/SplitPaneDemo2.java

另外，在以下行中，该方法甚至不存在。我正在使用 getContentPane() 代替。

 JSplitPane top = splitPaneDemo.getSplitPane();

Answer 1

该演示运行得很好。这是您的修改不起作用:)

这个确实起作用：

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 * are met:
 *
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 *     from this software without specific prior written permission.
 *
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 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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 */ 
import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;

public class SplitPaneDemo2 extends JFrame
        implements ListSelectionListener {

    private JLabel label;

    public SplitPaneDemo2() {
        super("SplitPaneDemo2");

        //Create an instance of SplitPaneDemo
        SplitPaneDemo splitPaneDemo = new SplitPaneDemo();
        JSplitPane top = splitPaneDemo.getSplitPane();
        splitPaneDemo.getImageList().addListSelectionListener(this);

        //XXXX: Bug #4131528, borders on nested split panes accumulate.
        //Workaround: Set the border on any split pane within
        //another split pane to null. Components within nested split
        //panes need to have their own border for this to work well.
        top.setBorder(null);

        //Create a regular old label
        label = new JLabel("Click on an image name in the list.",
                JLabel.CENTER);

        //Create a split pane and put "top" (a split pane)
        //and JLabel instance in it.
        JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
                top, label);
        splitPane.setOneTouchExpandable(true);
        splitPane.setDividerLocation(180);

        //Provide minimum sizes for the two components in the split pane
        top.setMinimumSize(new Dimension(100, 50));
        label.setMinimumSize(new Dimension(100, 30));

        //Add the split pane to this frame
        getContentPane().add(splitPane);
    }

    public void valueChanged(ListSelectionEvent e) {
        if (e.getValueIsAdjusting())
            return;

        JList theList = (JList) e.getSource();
        if (theList.isSelectionEmpty()) {
            label.setText("Nothing selected.");
        } else {
            int index = theList.getSelectedIndex();
            label.setText("Selected image number " + index);
        }
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Create and set up the window.
        JFrame frame = new SplitPaneDemo2();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //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();
            }
        });
    }
}

class SplitPaneDemo extends JPanel
        implements ListSelectionListener {
    private JLabel picture;
    private JList list;
    private JSplitPane splitPane;
    private String[] imageNames = {"Bird", "Cat", "Dog", "Rabbit", "Pig", "dukeWaveRed",
            "kathyCosmo", "lainesTongue", "left", "middle", "right", "stickerface"};

    public SplitPaneDemo() {

        //Create the list of images and put it in a scroll pane.

        list = new JList(imageNames);
        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        list.setSelectedIndex(0);
        list.addListSelectionListener(this);


        JScrollPane listScrollPane = new JScrollPane(list);
        picture = new JLabel();
        picture.setFont(picture.getFont().deriveFont(Font.ITALIC));
        picture.setHorizontalAlignment(JLabel.CENTER);

        JScrollPane pictureScrollPane = new JScrollPane(picture);

        //Create a split pane with the two scroll panes in it.
        splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,
                listScrollPane, pictureScrollPane);
        splitPane.setOneTouchExpandable(true);
        splitPane.setDividerLocation(150);

        //Provide minimum sizes for the two components in the split pane.
        Dimension minimumSize = new Dimension(100, 50);
        listScrollPane.setMinimumSize(minimumSize);
        pictureScrollPane.setMinimumSize(minimumSize);

        //Provide a preferred size for the split pane.
        splitPane.setPreferredSize(new Dimension(400, 200));
        updateLabel(imageNames[list.getSelectedIndex()]);
    }

    //Listens to the list
    public void valueChanged(ListSelectionEvent e) {
        JList list = (JList) e.getSource();
        updateLabel(imageNames[list.getSelectedIndex()]);
    }

    //Renders the selected image
    protected void updateLabel(String name) {
        ImageIcon icon = createImageIcon("images/" + name + ".gif");
        picture.setIcon(icon);
        if (icon != null) {
            picture.setText(null);
        } else {
            picture.setText("Image not found");
        }
    }

    //Used by SplitPaneDemo2
    public JList getImageList() {
        return list;
    }

    public JSplitPane getSplitPane() {
        return splitPane;
    }


    /**
     * Returns an ImageIcon, or null if the path was invalid.
     */
    protected static ImageIcon createImageIcon(String path) {
        java.net.URL imgURL = SplitPaneDemo.class.getResource(path);
        if (imgURL != null) {
            return new ImageIcon(imgURL);
        } else {
            System.err.println("Couldn't find file: " + path);
            return null;
        }
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {

        //Create and set up the window.
        JFrame frame = new JFrame("SplitPaneDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        SplitPaneDemo splitPaneDemo = new SplitPaneDemo();
        frame.getContentPane().add(splitPaneDemo.getSplitPane());

        //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();
            }
        });
    }
}

您可以将其全部粘贴到名为 SplitPaneDemo2.java 的文件中，然后编译并运行它。

原始来源：

• SplitPaneDemo.java
• SplitPaneDemo2.java

Answer 2

getContentPane () 是以前的方法。今天，您只需在框架上添加一个面板，即可放置东西。