在我之前的问题中，我说过我对 Java 的 JFrame 功能有些陌生。我正在尝试创建一个 JFileChooser，它将获取一个目录，其中setup.exe将保存一个名为的文件。不过，这无关紧要。我收到此错误：
C:\Users\b\Downloads\files\thankyousanta>javac UpdateMechanism.java
UpdateMechanism.java:31: error: <identifier> expected
fc.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
^
UpdateMechanism.java:31: error: <identifier> expected
fc.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
^
UpdateMechanism.java:33: error: <identifier> expected
openButton.addActionListener(openButton);
^
UpdateMechanism.java:33: error: <identifier> expected
openButton.addActionListener(openButton);
^
4 errors
...对于此代码：
import java.awt.event.*;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontFormatException;
import java.awt.GraphicsEnvironment;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.Scanner;
import javax.swing.filechooser.*;
import javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.JTextArea;
import javax.swing.JScrollPane;
import javax.swing.JFileChooser;
import javax.swing.BoxLayout;
import javax.Swing.SwingUtilities;
import javax.swing.BorderFactory;
import javax.swing.border.EmptyBorder;
import javax.imageio.ImageIO;
public class definitiveVoid extends JFileChooser implements ActionListener {
JFileChooser fc = new JFileChooser();
fc.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
JButton openButton = new JButton("The update is waiting on you.");
openButton.addActionListener(openButton);
}
public class UpdateMechanism extends JPanel
implements ActionListener {
public void actionPerformed(ActionEvent e) {
if (e.getSource() == openButton) {
int returnVal = fc.showOpenDialog(UpdateMechanism.this);
if (returnVal == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
} else {
// operation cancelled
}
} else {
// destroy life
}
}
private static String readURL(String targetURL) {
String returnish = "";
try {
URL tempURL = new URL(targetURL);
Scanner s = new Scanner(tempURL.openStream());
while (s.hasNextLine()) {
returnish = returnish+s.nextLine();
}
} catch (IOException e) {
System.out.println(e);
}
return returnish;
}
private static String readFile(String targetFile) {
String returnString = "";
try {
File tempFile = new File(targetFile);
Scanner s = new Scanner(tempFile);
while (s.hasNextLine()) {
returnString = returnString + s.nextLine();
}
} catch(IOException e) {
// !
System.out.println(e);
}
return returnString;
}
private static void showGUI() {
JFrame frame = new JFrame("The Neverhood Restoration Project");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(new Dimension(1024, 600));
frame.setExtendedState(frame.MAXIMIZED_BOTH);
frame.getContentPane().setBackground(new Color(0xA64343));
File fileCheck = new File("C:/Program Files (x86)");
String returnString = null;
String rootDirectory = null;
if (fileCheck.exists()) {
rootDirectory = "C:/Program Files (x86)/DreamWorks Interactive";
String checkFile = rootDirectory+"/Neverhood/version.txt";
File tempFile = new File(checkFile);
if (tempFile.exists()) {
returnString = readFile(checkFile);
} else {
returnString = "It appears you do not have the Neverhood Restoration Project installed, or you are using an earlier version.";
}
} else {
rootDirectory = "C:/Program Files/DreamWorks Interactive";
String checkFile = rootDirectory+"/Neverhood/version.txt";
File tempFile = new File(checkFile);
if (tempFile.exists()) {
returnString = readFile(checkFile);
} else {
returnString = "It appears you do not have the Neverhood Restoration Project installed, or you are using an earlier version.";
}
}
if (returnString.equals(readURL("http://theneverhood.sourceforge.net/version.txt"))) {
returnString = "You are updated to the recent version!";
} else {
returnString = "It appears you're not updated.";
}
JLabel headerLabel = new JLabel("The Neverhood Restoration Project");
headerLabel.setHorizontalAlignment(JLabel.CENTER);
JPanel heapPanel = new JPanel();
heapPanel.setLayout(new BoxLayout(heapPanel, BoxLayout.PAGE_AXIS));
heapPanel.setPreferredSize(new Dimension(500, heapPanel.getPreferredSize().height));
JTextArea heapLabel = new JTextArea(50, 50);
heapLabel.setLineWrap(true);
heapLabel.setWrapStyleWord(true);
heapLabel.setEditable(false);
heapLabel.setBorder(BorderFactory.createEmptyBorder(10, 20, 10, 20));
heapLabel.setFont(new Font("Serif", Font.PLAIN, 14));
heapLabel.append("Current version: "+readURL("http://theneverhood.sourceforge.net/prettyversion.txt")+".\nInstalled version: "+readFile(rootDirectory+"/Neverhood/prettyversion.txt")+".\n"+returnString+"\n" +
"You can read the full version of the document to the left at http://theneverhood.sourceforge.net."
+ "\nBelow is the download button. Just click, choose your directory to save setup.exe in and enjoy!");
heapPanel.add(heapLabel);
try {
Font sFont = Font.createFont(Font.TRUETYPE_FONT, new File("DUGFB___.TTF"));
sFont = sFont.deriveFont(Font.PLAIN, 48);
GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
ge.registerFont(sFont);
headerLabel.setFont(sFont);
} catch (FontFormatException | IOException e) {
System.out.println(e);
}
BufferedImage icoImage = null;
try {
icoImage = ImageIO.read(
frame.getClass().getResource("/nhood.bmp"));
} catch (IOException e) {
System.out.println(e);
}
frame.setIconImage(icoImage);
JEditorPane updateLog = new JEditorPane();
JScrollPane scrollPane = new JScrollPane(updateLog);
updateLog.setEditable(false);
try {
updateLog.setPage("http://theneverhood.sourceforge.net/");
} catch (IOException e) {
updateLog.setContentType("text/html");
updateLog.setText("<html>The application could not load the webpage.</html>");
}
frame.add(headerLabel, BorderLayout.NORTH);
frame.add(scrollPane);
frame.add(heapPanel, BorderLayout.EAST);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
showGUI();
}
});
}
}