title: How can I populate a JTree with an FTP directory?
body: <p>I am using FTP4j and I want to populate a JTree  with the root directory of an FTP server. I've tried using FTP4j's currentDirectory() method, but that only returns a "/" which isn't useful. I've also tried passing the ftp:// url to a method that initializes the JTree, which doesn't work either. This is my first Swing program so I'm kind of stumped on where to go. Here is the code:</p>
  
  <pre><code>package net.emptybox.ui;
  
  import java.awt.EventQueue;
  
  import javax.swing.JFrame;
  import net.miginfocom.swing.MigLayout;
  import javax.swing.JButton;
  import java.awt.event.ActionListener;
  import java.awt.event.ActionEvent;
  import javax.swing.JLabel;
  import javax.swing.JTextField;
  import java.awt.FlowLayout;
  import java.awt.BorderLayout;
  import javax.swing.BoxLayout;
  import javax.swing.JSplitPane;
  import javax.swing.JSeparator;
  import javax.swing.JTree;
  import javax.swing.JTextArea;
  import java.awt.Component;
  import java.io.File;
  
  import net.emptybox.ui.FTP;
  
  import javax.swing.Box;
  import javax.swing.event.TreeSelectionEvent;
  import javax.swing.event.TreeSelectionListener;
  import javax.swing.JScrollPane;
  import javax.swing.ScrollPaneConstants;
  
  
  
  public class GUI {
  
      static JFrame frame;
      static private JSplitPane splitPane;
      static private JLabel lblServer;
      static private JTextField serverField;
      static private JLabel lblPort;
      static private JTextField portField;
      static private JLabel lblUsername;
      static private JTextField usernameField;
      static private JLabel lblPassword;
      static private JTextField passwordField;
      static private JButton connectButton;
      static private JSeparator separator;
      static private JTextArea detailArea;
      static private JButton downloadButton;
      static private JButton uploadButton;
      static private Component horizontalGlue;
      static private JTextField fileField;
      static private JButton goButton;
      static private Component horizontalGlue_1;
  
      static FileSystemModel fileSystemModel;
      static JLabel consoleLabel;
      private static Component verticalGlue;
      private static JScrollPane scrollPane;
      static JTree fileTree;
  
      /**
       * Launch the application.
       */
  
      /**
       * Create the application.
       */
      public GUI() {
          initialize();
      }
  
      /**
       * Initialize the contents of the frame.
       */
      public static void initialize() {
          frame = new JFrame();
          frame.setBounds(100, 100, 648, 300);
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.getContentPane().setLayout(new MigLayout("", "[grow]", "[][][][grow][]"));
  
          lblServer = new JLabel("Server:");
          frame.getContentPane().add(lblServer, "flowx,cell 0 0");
  
          consoleLabel = new JLabel("");
          frame.getContentPane().add(consoleLabel, "flowx,cell 0 1");
  
          separator = new JSeparator();
          frame.getContentPane().add(separator, "cell 0 2");
  
          splitPane = new JSplitPane();
          splitPane.setOneTouchExpandable(true);
          splitPane.setContinuousLayout(true);
          frame.getContentPane().add(splitPane, "cell 0 3,grow");
  
          detailArea = new JTextArea();
          detailArea.setEditable(false);
          splitPane.setRightComponent(detailArea);
  
          scrollPane = new JScrollPane();
          scrollPane.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
          splitPane.setLeftComponent(scrollPane);
  
          serverField = new JTextField();
          frame.getContentPane().add(serverField, "cell 0 0,growx");
  
          lblPort = new JLabel("Port:");
          frame.getContentPane().add(lblPort, "cell 0 0");
  
          portField = new JTextField();
          frame.getContentPane().add(portField, "cell 0 0,growx");
  
          lblUsername = new JLabel("Username:");
          frame.getContentPane().add(lblUsername, "cell 0 0");
  
          usernameField = new JTextField();
          frame.getContentPane().add(usernameField, "cell 0 0,growx");
  
          lblPassword = new JLabel("Password:");
          frame.getContentPane().add(lblPassword, "cell 0 0");
  
          passwordField = new JTextField();
          frame.getContentPane().add(passwordField, "cell 0 0,growx");
  
  
          connectButton = new JButton("Connect");
          frame.getContentPane().add(connectButton, "cell 0 0");
  
          if (serverField.getText() == null || usernameField.getText() == null || passwordField.getText() == null) {
              connectButton.disable();
          } else {
              connectButton.enable();
          }
  
          if (portField.getText() == null) {
              portField.setText("21");
          }
  
          connectButton.addActionListener(new ActionListener() {
              public void actionPerformed(ActionEvent arg0) {
                  FTP.connect(serverField.getText(), portField.getText(), usernameField.getText(), passwordField.getText());
              }
          });
  
          downloadButton = new JButton("Download");
          frame.getContentPane().add(downloadButton, "flowx,cell 0 4");
          downloadButton.addActionListener(new ActionListener() {
              public void actionPerformed(ActionEvent arg0) {
              }
          });
  
          uploadButton = new JButton("Upload");
          frame.getContentPane().add(uploadButton, "cell 0 4");
          uploadButton.addActionListener(new ActionListener() {
              public void actionPerformed(ActionEvent arg0) {
              }
          });
  
          horizontalGlue_1 = Box.createHorizontalGlue();
          frame.getContentPane().add(horizontalGlue_1, "cell 0 4,growx");
  
          fileField = new JTextField();
          frame.getContentPane().add(fileField, "cell 0 4");
          fileField.setColumns(200);
  
          goButton = new JButton("Go");
          goButton.addActionListener(new ActionListener() {
              public void actionPerformed(ActionEvent arg0) {
              }
          });
          frame.getContentPane().add(goButton, "cell 0 4");
  
          horizontalGlue = Box.createHorizontalGlue();
          frame.getContentPane().add(horizontalGlue, "cell 0 4,alignx leading");
  
          verticalGlue = Box.createVerticalGlue();
          frame.getContentPane().add(verticalGlue, "cell 0 1");
      }
  
      private String getFileDetails(File file) {
          if (file == null)
            return "";
          StringBuffer buffer = new StringBuffer();
          buffer.append("Name: " + file.getName() + "\n");
          buffer.append("Path: " + file.getPath() + "\n");
          buffer.append("Size: " + file.length() + "\n");
          return buffer.toString();
        }
  
      public static void populateTree(String directory) {
          fileSystemModel = new FileSystemModel(new File(directory));
  
          fileTree = new JTree(fileSystemModel);
          scrollPane.setViewportView(fileTree);
      }
  }
  </code></pre>
  
  <p>Populate tree is called by another class when a connection is successfully established with the server and the user has logged in.</p>