我对我的Java GUI程序有疑问。当我正在处理它时，它运行正常，但是当它应该显示几个按钮时，它突然停止在窗口中显示任何内容。该窗口看起来像具有正确标题的默认JFrame。我以为它可能是日食的问题，但我不确定。请帮忙，我需要尽快转过来......
以下是GUI类的代码：
package gui;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import image.PixelImage;
/**
*
* @author ???
* @version ???
*/
public class SnapShopGUI extends JFrame {
/**
*
*/
private static final long serialVersionUID = 1L;
/**
* Tracks whether there is currently an image loaded into the application.
*/
private boolean myIsLoaded;
/**
* The image File.
*/
private static PixelImage myImage;
/**
* The JFrame holding all window data.
*/
private final JFrame mySSWin;
/**
* List to hold all the filter buttons.
*/
private final List<JButton> myFilterButtons;
/**
* List to hold all the image buttons.
*/
private final List<JButton> myImageButtons;
/**
* JFileChooser for open and save dialogs.
*/
private final JFileChooser myFC;
private final JLabel myImageLabel;
/**
* JLabel to actually make it possible to remove the picture from the JFrame
* because apparently I can't just reference the JLabel in the JFrame like any
* other collection ever, I need the exact damn object.
*/
private final JPanel myImagePanel;
/**
* Constructor that creates the JFrame.
*/
public SnapShopGUI() {
super();
myImagePanel = new JPanel();
myImageLabel = new JLabel();
mySSWin = new JFrame("TCSS 305 SnapShop");
myIsLoaded = false;
myFilterButtons = new ArrayList<JButton>();
myImageButtons = new ArrayList<JButton>();
myFC = new JFileChooser();
}
/**
* Method that runs to initialize the GUI window.
*/
public void start() {
// Instantiate component variables
final JPanel p1 = new JPanel(new BorderLayout());
final JPanel p2 = new JPanel(new GridLayout(7, 1, 0, 3));
final JPanel p3 = new JPanel(new GridLayout(3, 1, 0, 3));
// myFilterButtons.add(makeButton("EDGE_DETECT"));
myFilterButtons.add(new JButton("Flip Horizontal"));
myFilterButtons.add(new JButton("Flip Vertical"));
myFilterButtons.add(new JButton("Grayscale"));
myFilterButtons.add(new JButton("Sharpen"));
myFilterButtons.add(new JButton("Soften"));
myImageButtons.add(new JButton("Open..."));
myImageButtons.add(new JButton("Save as..."));
myImageButtons.add(new JButton("Close Image"));
// Set up buttons
toggleButtons();
myImageButtons.get(0).addActionListener(new ActionListener() {
@Override
public void actionPerformed(final ActionEvent theE) {
getNewImage();
}
});
myImageButtons.get(1).addActionListener(new ActionListener() {
@Override
public void actionPerformed(final ActionEvent theE) {
saveImage();
}
});
myImageButtons.get(2).addActionListener(new ActionListener() {
@Override
public void actionPerformed(final ActionEvent theE) {
closeImage();
}
});
// Tweak JFrame and JFileChooser
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setResizable(true);
setLayout(new BorderLayout());
final File workingDir = new File(System.getProperty("user.dir"));
myFC.setCurrentDirectory(workingDir);
// Add components to JFrame
for (final JButton b : myFilterButtons) {
p2.add(b);
}
for (final JButton b : myImageButtons) {
p3.add(b);
}
p1.add(p2, BorderLayout.NORTH);
p1.add(p3, BorderLayout.SOUTH);
add(p1, BorderLayout.WEST);
resizeWindow();
}
/**
* Returns the current image.
*
* @return The image as a PixelImage
*/
public static PixelImage getImage() {
return myImage;
}
/**
* Used by buttons to get a new image from the user and update the currently
* displayed image.
*
* @throws IOException If user passes a file that is not an image.
*/
private void getNewImage() {
final int returnVal = myFC.showOpenDialog(mySSWin);
if (returnVal == JFileChooser.APPROVE_OPTION) {
if (!myIsLoaded) {
toggleButtons();
}
if (myIsLoaded) {
mySSWin.remove(myImagePanel);
mySSWin.revalidate();
mySSWin.repaint();
}
try {
myImage = PixelImage.load(myFC.getSelectedFile());
myImageLabel.setIcon(new ImageIcon(myImage));
} catch (final IOException e) {
JOptionPane.showMessageDialog(mySSWin,
"Please choose an image file.",
"Cannot load file", JOptionPane.ERROR_MESSAGE);
}
myIsLoaded = true;
myImagePanel.add(myImageLabel, BorderLayout.NORTH);
mySSWin.add(myImagePanel, BorderLayout.CENTER);
resizeWindow();
}
}
/**
* Creates a filter button for the start method.
*
* @param theButton A String defining what button to make.
* @return The JButton.
*/
private JButton makeButton(final String theButton) throws IllegalArgumentException {
final JButton b = new JButton();
switch (theButton) {
case "EDGE_DETECT": b.addActionListener(new EdgeDetectListener());
break;
case "EDGE_HIGHLIGHT": b.addActionListener(new EdgeHighlightListener());
break;
// case "FLIP_HORIZONTAL": b.addActionListener(new FlipHorizonalListener());
// break;
//
// case "FLIP_VERTICAL": b.addActionListener(new FlipVerticalListener());
// break;
//
// case "GRAYSCALE": b.addActionListener(new GrayscaleListener());
// break;
//
// case "SHARPEN": b.addActionListener(new SharpenListener());
// break;
//
// case "SOFTEN": b.addActionListener(new SoftenListener());
// break;
//
// default: throw new IllegalArgumentException("makeButton() must be called "
// + "with a proper filter!");
}
return b;
}
/**
* Saves the currently displayed picture to the user's computer.
*/
private void saveImage() {
final int rVal = myFC.showSaveDialog(mySSWin);
if (rVal == JFileChooser.APPROVE_OPTION) {
try {
myImage.save(myFC.getSelectedFile());
} catch (final IOException e) {
e.printStackTrace();
}
}
}
/**
* Enables/disables all filter buttons at once.
*/
private void toggleButtons() {
for (final JButton b : myFilterButtons) {
b.setEnabled(!b.isEnabled());
}
for (int i = 1; i <= 2; i++) {
myImageButtons.get(i).setEnabled(!myImageButtons.get(i).isEnabled());
}
}
/**
* Packs the window the the size of the components and ensures components
* cannot be covered. Also resets the window position to the center.
*/
private void resizeWindow() {
mySSWin.setVisible(false);
mySSWin.setMinimumSize(new Dimension(0, 0));
mySSWin.pack();
mySSWin.setMinimumSize(new Dimension(mySSWin.getSize()));
mySSWin.setLocationRelativeTo(null);
mySSWin.setVisible(true);
}
/**
* Closes the image.
*/
private void closeImage() {
mySSWin.remove(myImagePanel);
mySSWin.revalidate();
mySSWin.repaint();
if (myIsLoaded) {
toggleButtons();
}
myIsLoaded = false;
resizeWindow();
}
}
有些代码已被注释掉，但应该在此状态下在窗口内显示内容。