GUI程序在Netbeans之外崩溃但内部很好

Question

因此，这是一个与FTP服务器联系的相对基本的程序，并记录存在的文件。它使用GUI来启动和启动进程。但是，在Netbeans之外（作为独立的.jar或Eclipse），一旦按下开始按钮（内部类启动），它就会崩溃。我无法理解为什么会发生这种情况所以非常感谢任何帮助。

public class GUI {

private JFrame frame;
private JPanel jPanel;
private FTPSearch demo;

public GUI() {
    initialise();

}

public void initialise() {
    //set nimbus look and feel
    try {
        for (UIManager.LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (Exception e) {
        e.printStackTrace();

    }

    frame = new JFrame();
    jPanel = new JPanel();
    jPanel.setPreferredSize(new Dimension(500, 500));
    JButton jButton = new JButton("Start");
    jButton.addActionListener(new Start());
    jPanel.add(jButton);
    frame.setContentPane(jPanel);
    frame.setTitle("FTP Communicator");
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    frame.pack();
    demo = new FTPSearch();
}

public static void main(String[] args) {
    EventQueue.invokeLater(() -> {
        try {
            GUI window = new GUI();
            window.frame.setVisible(true);

        } catch (Exception e) {
            e.printStackTrace();
        }
    });
}

class Start implements ActionListener {

    @Override
    public void actionPerformed(ActionEvent arg0) {

        EventQueue.invokeLater(() -> {
            try {

                demo.searchAndLog();

            } catch (Exception e) {
                e.printStackTrace();
            }
        });

    }
}

}

然后是FTP类：

public class FTPSearch {

String server;
int port;
String user;
String password;
FTPClient Client;

public FTPSearch() {
    server = "ftp.pagesuite.com";
    port = 21;
    user = "tim";
    password = "access28";
    Client = new FTPClient();
}

public void searchAndLog() {
    try {

        Client.connect(server, port);

        int reply = Client.getReplyCode();
        if (!FTPReply.isPositiveCompletion(reply)) {
            System.out.println("Connect fail");
            return;
        }

        boolean ableToConnect = Client.login(user, password);

        if (!ableToConnect) {
            System.out.println("Login Fail");
            return;
        }

        String[] files2 = Client.listNames();
        //String dir2 = ftpClient.printWorkingDirectory();
        //System.out.println("directory is: " + dir2);
        printNames(files2);
        logNames(files2);

    } catch (IOException ex) {
        ex.printStackTrace();
    } finally {

        try {
            if (Client.isConnected()) {
                Client.logout();
                Client.disconnect();
                System.out.println("logged out");
            }
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
}

private static void printNames(String files[]) {
    if (files != null && files.length > 0) {
        for (String aFile : files) {
            System.out.println(aFile);
        }
    }
}

private static void logNames(String files[]) {
    if (files != null && files.length > 0) {
        for (String aFile : files) {
            writeToLog(aFile);
        }
    }
}

private static void showServerReply(FTPClient ftpClient) {
    String[] replies = ftpClient.getReplyStrings();
    if (replies != null && replies.length > 0) {
        for (String reply : replies) {
            System.out.println("SERVER: " + reply);
        }
    }
}

public static void writeToLog(String log) {
    File f = new File("LogFile.txt");
    boolean exists = f.exists();

    if (!exists) {
        try {
            f.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    FileWriter fWriter;

    try {
        fWriter = new FileWriter(f, true);
        BufferedWriter out = new BufferedWriter(fWriter);
        out.write(log + "\n");
        out.newLine();
        out.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

}
 }

所以这里似乎失败了：

        System.out.println("attempt to retrieve names");
        String[] files2 = Client.listNames();
        System.out.println("names retrieved");

它将打印第一个语句，但永远不会到达第二个打印。它必须在第二行代码上失败，不知道为什么......