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Create a lazy file tree
/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
//package org.eclipse.swt.snippets;
 
/*
 * Tree example snippet: create a tree (lazy)
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */
import java.io.File;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeItem;

public class FileTreeLazy{
  
public static void main (String [] args) {
  final Display display = new Display ();
  final Shell shell = new Shell (display);
  shell.setText ("Lazy Tree");
  shell.setLayout (new FillLayout ());
  final Tree tree = new Tree (shell, SWT.BORDER);
  File [] roots = File.listRoots ();
  for (int i=0; i<roots.length; i++) {
    TreeItem root = new TreeItem (tree, 0);
    root.setText (roots [i].toString ());
    root.setData (roots [i]);
    new TreeItem (root, 0);
  }
  tree.addListener (SWT.Expand, new Listener () {
    public void handleEvent (final Event event) {
      final TreeItem root = (TreeItem) event.item;
      TreeItem [] items = root.getItems ();
      for (int i= 0; i<items.length; i++) {
        if (items [i].getData () != null) return;
        items [i].dispose ();
      }
      File file = (File) root.getData ();
      File [] files = file.listFiles ();
      if (files == null) return;
      for (int i= 0; i<files.length; i++) {
        TreeItem item = new TreeItem (root, 0);
        item.setText (files [i].getName ());
        item.setData (files [i]);
        if (files [i].isDirectory()) {
          new TreeItem (item, 0);
        }
      }
    }
  });
  Point size = tree.computeSize (300, SWT.DEFAULT);
  int width = Math.max (300, size.x);
  int height = Math.max (300, size.y);
  shell.setSize (shell.computeSize (width, height));
  shell.open ();
  while (!shell.isDisposed ()) {
    if (!display.readAndDispatch ()) display.sleep ();
  }
  display.dispose ();
}
}








17.63.File Tree
17.63.1.Create a lazy file treeCreate a lazy file tree
17.63.2.System File TreeSystem File Tree