for JTree File System Display Create an application that uses a JTree to display the contents of a portion of the local file system. Using the JFileChooser dialog, allow the user to pick a directory to use as the root of the directory tree. Using methods of class File (package java.io), navigate from this directory through its files and subdirectories. During the traversal of the directory tree, build a parallel JTree using DefaultMutableTreeNode objects. The user object for each node should be a reference to the corresponding file or directory. At the end of the traversal, set the root of the directory tree to be the root node of a JTree object. Display the JTree object on the GUI.
Additional Features A common organization for GUIs using JTree-based data display is to use a JSplitPane with the JTree on the left side panel, and the display of information associated with the currently selected node in the right side panel. For example, you could use this GUI skeleton to implement an image browser or Java source code browser. Example Implementation Below is code for a simplified implementation that allows the user to pick a file, then build a string representation of all files/directories within the file system subtree starting at the chosen file. The string is then displayed as text in a JOptionPane dialog box. The method String getFileNames() is the recursive method that builds the String. For this exercise, start by rewriting the getFileNames() method to build a JTree instead of a String. At every level in the hierarchy, the method should build a DefaultMutableTreeNode, make recursive calls to build subtrees, add subtree nodes to the current node, and then finally return a reference to the original node. Once the nodes have been built, the root node is added to a JTree, the JTree is placed into a JScrollPane, and the is JScrollPane displayed on the GUI.
import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.io.*; import javax.swing.tree.*; public class FileDemo extends JPanel { JFileChooser fc; JButton btnfc; public FileDemo() { super(true); fc = new JFileChooser(); fc.setFileSelectionMode(JFileChooser.FILES_AND_DIRECTORIES); btnfc = new JButton("Choose File"); add(btnfc); // action listener for the choose file button // will open the file choose and allow the user to pick a directory btnfc.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { int fcstatus = fc.showOpenDialog(FileDemo.this); if (fcstatus == JFileChooser.APPROVE_OPTION) { // build string list of file/directory names String s = getFileNames(fc.getSelectedFile(),0); // place string into a text pane, and display it JTextPane tp = new JTextPane(); tp.setText(s); JScrollPane sp = new JScrollPane(tp); sp.setPreferredSize(new Dimension(400,300)); JOptionPane.showConfirmDialog(FileDemo.this, sp); } } }); } public static void buildGUI() { JFrame f = new JFrame("File Demo")...