FileTreeDemo.java Source code

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Here is the source code for FileTreeDemo.java

Source

/*
 * This example is from the book "Java Foundation Classes in a Nutshell".
 * Written by David Flanagan. Copyright (c) 1999 by O'Reilly & Associates.  
 * You may distribute this source code for non-commercial purposes only.
 * You may study, modify, and use this example for any purpose, as long as
 * this notice is retained.  Note that this example is provided "as is",
 * WITHOUT WARRANTY of any kind either expressed or implied.
 */

import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;
import java.io.File;

public class FileTreeDemo {
    public static void main(String[] args) {
        // Figure out where in the filesystem to start displaying
        File root;
        if (args.length > 0)
            root = new File(args[0]);
        else
            root = new File(System.getProperty("user.home"));

        // Create a TreeModel object to represent our tree of files
        FileTreeModel model = new FileTreeModel(root);

        // Create a JTree and tell it to display our model
        JTree tree = new JTree();
        tree.setModel(model);

        // The JTree can get big, so allow it to scroll.
        JScrollPane scrollpane = new JScrollPane(tree);

        // Display it all in a window and make the window appear
        JFrame frame = new JFrame("FileTreeDemo");
        frame.getContentPane().add(scrollpane, "Center");
        frame.setSize(400, 600);
        frame.setVisible(true);
    }
}

/**
 * The methods in this class allow the JTree component to traverse
 * the file system tree, and display the files and directories.
 **/
class FileTreeModel implements TreeModel {
    // We specify the root directory when we create the model.
    protected File root;

    public FileTreeModel(File root) {
        this.root = root;
    }

    // The model knows how to return the root object of the tree
    public Object getRoot() {
        return root;
    }

    // Tell JTree whether an object in the tree is a leaf or not
    public boolean isLeaf(Object node) {
        return ((File) node).isFile();
    }

    // Tell JTree how many children a node has
    public int getChildCount(Object parent) {
        String[] children = ((File) parent).list();
        if (children == null)
            return 0;
        return children.length;
    }

    // Fetch any numbered child of a node for the JTree.
    // Our model returns File objects for all nodes in the tree.  The
    // JTree displays these by calling the File.toString() method.
    public Object getChild(Object parent, int index) {
        String[] children = ((File) parent).list();
        if ((children == null) || (index >= children.length))
            return null;
        return new File((File) parent, children[index]);
    }

    // Figure out a child's position in its parent node.
    public int getIndexOfChild(Object parent, Object child) {
        String[] children = ((File) parent).list();
        if (children == null)
            return -1;
        String childname = ((File) child).getName();
        for (int i = 0; i < children.length; i++) {
            if (childname.equals(children[i]))
                return i;
        }
        return -1;
    }

    // This method is only invoked by the JTree for editable trees.  
    // This TreeModel does not allow editing, so we do not implement 
    // this method.  The JTree editable property is false by default.
    public void valueForPathChanged(TreePath path, Object newvalue) {
    }

    // Since this is not an editable tree model, we never fire any events,
    // so we don't actually have to keep track of interested listeners.
    public void addTreeModelListener(TreeModelListener l) {
    }

    public void removeTreeModelListener(TreeModelListener l) {
    }
}