path: root/javax/swing/filechooser/FileSystemView.java

/* FileSystemView.java --
   Copyright (C) 2002, 2004, 2005  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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package javax.swing.filechooser;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;

import javax.swing.Icon;
import javax.swing.JFileChooser;


/**
 * The base class providing a view of the file system for use by the 
 * {@link JFileChooser} component.
 */
public abstract class FileSystemView
{
  /** The instance returned by {@link #getFileSystemView()}. */
  private static FileSystemView defaultFileSystemView;
  
  /**
   * Creates a new file object with the given name in the specified directory.
   *
   * @param dir  the directory (<code>null</code> permitted).
   * @param filename  the file name.
   *
   * @return A new file object.
   */
  public File createFileObject(File dir, String filename)
  {
    return new File(dir, filename);
  }

  /**
   * Creates a new file object from the specified path.
   *
   * @param path  the path.
   *
   * @return A new file object.
   */
  public File createFileObject(String path)
  {
    File f = new File(path);
    if (isFileSystemRoot(f))
      f = this.createFileSystemRoot(f);
    return f;
  }

  /**
   * DOCUMENT ME!
   *
   * @param f DOCUMENT ME!
   *
   * @return DOCUMENT ME!
   */
  protected File createFileSystemRoot(File f)
  {
    File[] roots = File.listRoots();
    if (roots == null)
      return null;
    return roots[0];
  }

  /**
   * Creates a new folder with a unique name in the specified directory and
   * returns a {@link File} object representing the new directory.
   *
   * @param containingDir  the directory to contain the new folder 
   *                       (<code>null</code> not permitted).
   *
   * @return A {@link File} object representing the new directory.
   *
   * @throws IOException if an exception occurs while creating the new 
   *                     directory.
   */
  public abstract File createNewFolder(File containingDir)
                                throws IOException;

  /**
   * DOCUMENT ME!
   *
   * @param parent DOCUMENT ME!
   * @param fileName DOCUMENT ME!
   *
   * @return DOCUMENT ME!
   */
  public File getChild(File parent, String fileName)
  {
    // FIXME: Handle the case when parent and child are special folders.
    return new File(parent, fileName);
  }

  /**
   * Returns the default directory.
   *
   * @return The default directory.
   */
  public File getDefaultDirectory()
  {
    return getHomeDirectory();
  }

  /**
   * Returns an array containing the files in the given directory.  The 
   * <code>useFileHiding</code> controls whether or not hidden files are 
   * included in the result.
   *
   * @param dir  the directory (if <code>null</code>
   * @param useFileHiding  a flag that controls whether or not hidden files are
   *                       included in the result (pass in <code>true</code> to
   *                       exclude hidden files).
   *
   * @return The files in the given directory (possibly <code>null</code>).
   */
  public File[] getFiles(File dir, boolean useFileHiding)
  {
    if (dir == null || dir.listFiles() == null)
      return null;
    File[] files = dir.listFiles();
    if (! useFileHiding)
      return files;
    ArrayList trim = new ArrayList();
    for (int i = 0; i < files.length; i++)
      if (! files[i].isHidden())
	trim.add(files[i]);
    File[] value = (File[]) trim.toArray(new File[trim.size()]);
    return value;
  }

  /**
   * Returns a default {@link FileSystemView} appropriate for the platform.
   *
   * @return A default {@link FileSystemView} appropriate for the platform.
   */
  public static FileSystemView getFileSystemView()
  {
    if (defaultFileSystemView == null)
      {
        // FIXME: We need to support other file systems too.
        defaultFileSystemView = new UnixFileSystemView();
      }
    return defaultFileSystemView;
  }

  /**
   * Returns the home directory for the current user.
   *
   * @return The home directory for the current user.
   */
  public File getHomeDirectory()
  {
    return createFileObject(System.getProperty("user.home"));
  }

  /**
   * Returns the parent directory for the given file/directory.
   *
   * @param f  the file/directory.
   *
   * @return The parent directory (or <code>null</code> if there is no parent
   *         directory).
   */
  public File getParentDirectory(File f)
  {
    if (f == null)
      return null;
    return f.getParentFile();
  }

  /**
   * Returns an array containing the file system roots.  On Unix-like platforms,
   * this array will contain just a single item ("/"), while other platforms
   * may return multiple roots.
   * <p>
   * This method is implemented to return <code>null</code>, subclasses must
   * override this method.
   *
   * @return An array containing the file system roots.
   */
  public File[] getRoots()
  {
    // subclass
    return null;
  }

  /**
   * Returns the name of a file as it would be displayed by the underlying 
   * system.
   *
   * @param f  the file.
   *
   * @return the name of a file as it would be displayed by the underlying 
   *         system
   *
   * @specnote The specification suggests that the information here is
   *           fetched from a ShellFolder class. This seems to be a non public
   *           private file handling class. We simply return File.getName()
   *           here and leave special handling to subclasses.
   */
  public String getSystemDisplayName(File f)
  {
    String name = null;
    if (f != null)
      name = f.getName();
    return name;
  }

  /**
   * Returns the icon that would be displayed for the given file by the 
   * underlying system.  This implementation returns <code>null</code>, 
   * subclasses must override.
   *
   * @param f  the file.
   *
   * @return <code>null</code>.
   */
  public Icon getSystemIcon(File f)
  {
    return null;
  }

  /**
   * Returns the type description of a file that would be displayed by the 
   * underlying system.  This implementation returns <code>null</code>, 
   * subclasses must override.
   *
   * @param f  the file.
   *
   * @return <code>null</code>.
   */
  public String getSystemTypeDescription(File f)
  {
    return null;
  }

  /**
   * DOCUMENT ME!
   *
   * @param dir DOCUMENT ME!
   *
   * @return DOCUMENT ME!
   */
  public boolean isComputerNode(File dir)
  {
    return false;
  }

  /**
   * Returns <code>true</code> if the given directory represents a disk 
   * drive, and <code>false</code> otherwise.  This default implementation
   * always returns <code>false</code>.
   *
   * @param dir  the directory.
   *
   * @return <code>false</code>.
   */
  public boolean isDrive(File dir)
  {
    return false;
  }

  /**
   * Returns <code>true</code> if <code>f</code> is a file or directory, and
   * <code>false</code> otherwise.
   *
   * @param f  the file/directory.
   *
   * @return <code>true</code> if <code>f</code> is a file or directory, and
   * <code>false</code> otherwise.
   */
  public boolean isFileSystem(File f)
  {
    return (f.isFile() || f.isDirectory());
  }

  /**
   * Returns <code>true</code> if the given directory is a file system root,
   * and <code>false</code> otherwise.
   *
   * @param dir  the directory.
   *
   * @return <code>true</code> if the given directory is a file system root,
   *          and <code>false</code> otherwise.
   */
  public boolean isFileSystemRoot(File dir)
  {
    File[] roots = File.listRoots();
    if (roots == null || dir == null)
      return false;
    String filename = dir.getAbsolutePath();
    for (int i = 0; i < roots.length; i++)
      if (roots[i].getAbsolutePath().equals(filename))
	return true;
    return false;
  }

  /**
   * Returns <code>true</code> if the given directory represents a floppy 
   * drive, and <code>false</code> otherwise.  This default implementation
   * always returns <code>false</code>.
   *
   * @param dir  the directory.
   *
   * @return <code>false</code>.
   */
  public boolean isFloppyDrive(File dir)
  {
    return false;
  }

  /**
   * Returns <code>true</code> if the given file is hidden, and 
   * <code>false</code> otherwise.
   *
   * @param f  the file.
   *
   * @return <code>true</code> if the given file is hidden, and 
   *         <code>false</code> otherwise.
   */
  public boolean isHiddenFile(File f)
  {
    return f.isHidden();
  }

  /**
   * Returns <code>true</code> if <code>folder</code> is the parent of 
   * <code>file</code>, and <code>false</code> otherwise.
   *
   * @param folder  the folder (<code>null</code> not permitted).
   * @param file  the file (<code>null</code> not permitted).
   *
   * @return <code>true</code> if <code>folder</code> is the parent of 
   *         <code>file</code>, and <code>false</code> otherwise.
   */
  public boolean isParent(File folder, File file)
  {
    File parent = file.getParentFile();
    if (parent == null)
      return false;
    return folder.equals(parent);
  }

  /**
   * DOCUMENT ME!
   *
   * @param f DOCUMENT ME!
   *
   * @return DOCUMENT ME!
   */
  public boolean isRoot(File f)
  {
    // These are not file system roots.
    return false;
  }

  /**
   * Returns <code>true</code> if the file is traversable, and 
   * <code>false</code> otherwise.  Here, all directories are considered
   * traversable, and files are considered non-traversable. 
   *
   * @param f  the file or directory (<code>null</code> not permitted).
   *
   * @return <code>true</code> if the file is traversable, and 
   *         <code>false</code> otherwise.
   */
  public Boolean isTraversable(File f)
  {
    // Tested. A directory where the user has no permission to rwx is still
    // traversable. (No files are listed when you traverse the directory)
    // My best guess is that as long as it's a directory, the file is
    // traversable.
    return Boolean.valueOf(f.isDirectory());
  }
}