implements TreeModel to display File in a Tree
/*
* 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) {}
}
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