無法使用expandPath方法擴展JTree

Question

I've used an example by Ian F. Darwin關於如何在JTree上顯示文件系統，儘管代碼對我來說很清楚，但我無法弄清楚爲什麼我無法展開valueChanged上的樹的TreeSelectionListener。下面的代碼：

package ericsonwrp.republica.vintage.caixa; 

/* 
* Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002. 
* All rights reserved. Software written by Ian F. Darwin and others. 
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $ 
* 
* Redistribution and use in source and binary forms, with or without 
* modification, are permitted provided that the following conditions 
* are met: 
* 1. Redistributions of source code must retain the above copyright 
* notice, this list of conditions and the following disclaimer. 
* 2. Redistributions in binary form must reproduce the above copyright 
* notice, this list of conditions and the following disclaimer in the 
* documentation and/or other materials provided with the distribution. 
* 
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' 
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS 
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
* POSSIBILITY OF SUCH DAMAGE. 
* 
* Java, the Duke mascot, and all variants of Sun's Java "steaming coffee 
* cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's, 
* pioneering role in inventing and promulgating (and standardizing) the Java 
* language and environment is gratefully acknowledged. 
* 
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for 
* inventing predecessor languages C and C++ is also gratefully acknowledged. 
*/ 

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.Container; 
import java.awt.Dimension; 
import java.io.File; 
import java.util.Collections; 
import java.util.Vector; 

import javax.swing.BoxLayout; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 
import javax.swing.JTree; 
import javax.swing.event.TreeSelectionEvent; 
import javax.swing.event.TreeSelectionListener; 
import javax.swing.tree.DefaultMutableTreeNode; 
import javax.swing.tree.TreePath; 

/** 
* Display a file system in a JTree view 
* 
* @version $Id: FileTree.java,v 1.9 2004/02/23 03:39:22 ian Exp $ 
* @author Ian Darwin 
*/ 
public class FileTree extends JPanel { 
    /** 
    * 
    */ 
    private static final long serialVersionUID = 1L; 
    private JTree tree; 
    private JScrollPane scrollpane; 

    /** Construct a FileTree */ 
    public FileTree(File dir) { 
     setLayout(new BorderLayout()); 

     tree = new JTree(addNodes(null, dir)); 
     tree.setRootVisible(false); 

     // Add a listener 
     tree.addTreeSelectionListener(new TreeSelectionListener() { 
      public void valueChanged(TreeSelectionEvent e) { 
       DefaultMutableTreeNode node = (DefaultMutableTreeNode) e 
         .getPath().getLastPathComponent(); 
       TreePath p = new TreePath(node.getPath()); 
       tree.expandPath(p); // HERE <<<<<<<<<<<<<< 
      } 
     }); 

     scrollpane = new JScrollPane(); 
     scrollpane.getViewport().add(tree); 
     add(BorderLayout.CENTER, scrollpane); 
    } 

    /** Add nodes from under "dir" into curTop. Highly recursive. */ 
    DefaultMutableTreeNode addNodes(DefaultMutableTreeNode curTop, File dir) { 
     String curPath = dir.getPath(); 
     DefaultMutableTreeNode curDir = new DefaultMutableTreeNode(curPath); 
     if (curTop != null) { // should only be null at root 
      curTop.add(curDir); 
     } 
     Vector<String> ol = new Vector<String>(); 
     String[] tmp = dir.list(); 
     for (int i = 0; i < tmp.length; i++) 
      ol.addElement(tmp[i]); 
     Collections.sort(ol, String.CASE_INSENSITIVE_ORDER); 
     File f; 
     Vector<String> files = new Vector<String>(); 
     // Make two passes, one for Dirs and one for Files. This is #1. 
     for (int i = 0; i < ol.size(); i++) { 
      String thisObject = (String) ol.elementAt(i); 
      String newPath; 
      if (curPath.equals(".")) 
       newPath = thisObject; 
      else 
       newPath = curPath + File.separator + thisObject; 
      if ((f = new File(newPath)).isDirectory()) 
       addNodes(curDir, f); 
      else 
       files.addElement(thisObject); 
     } 
     // Pass two: for files. 
     for (int fnum = 0; fnum < files.size(); fnum++) 
      curDir.add(new DefaultMutableTreeNode(files.elementAt(fnum))); 
     return curDir; 
    } 

    public Dimension getMinimumSize() { 
     return new Dimension(200, 400); 
    } 

    public Dimension getPreferredSize() { 
     return new Dimension(200, 400); 
    } 

} 

這裏是我的「文件選擇」與此JTree視覺例如：

正如你所看到的，節點應該對的valueChanged擴大，而不會發生（「遊戲」是一個文件夾）。

Answer 1

在你的圖片遊戲不是一個文件夾。看看your link的圖片。 addNodes()出錯了。您不能展開一片葉子;）

嘗試使用new File(".")調用FileTree。你應該看到你的項目文件夾。這對我有效。當我嘗試撥打new FileTree(new File("/"))以獲取所有文件夾...此處addNodes()失敗。使用this solution。

也許你必須做出一些改變：

... implements Comparable<File> { 

和

public int compareTo(File object)...