Java tutorial
/* * Copyright (c) 2002 Sun Microsystems, Inc. All Rights Reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * -Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * -Redistribution in binary form must reproduct the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the distribution. * * Neither the name of Sun Microsystems, Inc. or the names of contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * This software is provided "AS IS," without a warranty of any kind. ALL * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT * BE LIABLE FOR ANY DAMAGES OR LIABILITIES SUFFERED BY LICENSEE AS A RESULT * OF OR RELATING TO USE, MODIFICATION OR DISTRIBUTION OF THE SOFTWARE OR ITS * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE SOFTWARE, EVEN * IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. * * You acknowledge that Software is not designed, licensed or intended for * use in the design, construction, operation or maintenance of any nuclear * facility. */ /* * @(#)EasyFileFilter.java 1.13 02/06/13 */ import java.io.File; import java.util.Enumeration; import java.util.Hashtable; import javax.swing.filechooser.FileFilter; /** * A convenience implementation of FileFilter that filters out all files except * for those type extensions that it knows about. * * Extensions are of the type ".foo", which is typically found on Windows and * Unix boxes, but not on Macinthosh. Case is ignored. * * Example - create a new filter that filerts out all files but gif and jpg * image files: * * JFileChooser chooser = new JFileChooser(); EasyFileFilter filter = new * EasyFileFilter( new String{"gif", "jpg"}, "JPEG & GIF Images") * chooser.addChoosableFileFilter(filter); chooser.showOpenDialog(this); * * @version 1.13 06/13/02 * @author Jeff Dinkins */ public class EasyFileFilter extends FileFilter { private Hashtable<String, FileFilter> filters = null; private String description = null; private String fullDescription = null; private boolean useExtensionsInDescription = true; /** * Creates a file filter. If no filters are added, then all files are * accepted. * * @see #addExtension */ public EasyFileFilter() { this.filters = new Hashtable<String, FileFilter>(); } /** * Creates a file filter that accepts files with the given extension. * Example: new EasyFileFilter("jpg"); * * @see #addExtension */ public EasyFileFilter(String extension) { this(extension, null); } /** * Creates a file filter that accepts the given file type. Example: new * EasyFileFilter("jpg", "JPEG Image Images"); * * Note that the "." before the extension is not needed. If provided, it * will be ignored. * * @see #addExtension */ public EasyFileFilter(String extension, String description) { this(); if (extension != null) addExtension(extension); if (description != null) setDescription(description); } /** * Creates a file filter from the given string array. Example: new * EasyFileFilter(String {"gif", "jpg"}); * * Note that the "." before the extension is not needed adn will be ignored. * * @see #addExtension */ public EasyFileFilter(String[] filters) { this(filters, null); } /** * Creates a file filter from the given string array and description. * Example: new EasyFileFilter(String {"gif", "jpg"}, "Gif and JPG Images"); * * Note that the "." before the extension is not needed and will be ignored. * * @see #addExtension */ public EasyFileFilter(String[] filters, String description) { this(); for (int i = 0; i < filters.length; i++) { // add filters one by one addExtension(filters[i]); } if (description != null) setDescription(description); } /** * Return true if this file should be shown in the directory pane, false if * it shouldn't. * * Files that begin with "." are ignored. * * @see #getExtension * @see FileFilter#accept */ public boolean accept(File f) { if (f != null) { if (f.isDirectory()) { return true; } String extension = getExtension(f); if (extension != null && filters.get(getExtension(f)) != null) { return true; } } return false; } /** * Return the extension portion of the file's name . * * @see #getExtension * @see FileFilter#accept */ public String getExtension(File f) { if (f != null) { String filename = f.getName(); int i = filename.lastIndexOf('.'); if (i > 0 && i < filename.length() - 1) { return filename.substring(i + 1).toLowerCase(); } } return null; } /** * Adds a filetype "dot" extension to filter against. * * For example: the following code will create a filter that filters out all * files except those that end in ".jpg" and ".tif": * * EasyFileFilter filter = new EasyFileFilter(); filter.addExtension("jpg"); * filter.addExtension("tif"); * * Note that the "." before the extension is not needed and will be ignored. */ public void addExtension(String extension) { if (filters == null) { filters = new Hashtable<String, FileFilter>(5); } filters.put(extension.toLowerCase(), this); fullDescription = null; } /** * Returns the human readable description of this filter. For example: "JPEG * and GIF Image Files (*.jpg, *.gif)" * * @see FileFilter#getDescription */ public String getDescription() { if (fullDescription == null) { if (description == null || isExtensionListInDescription()) { fullDescription = description == null ? "(" : description + " ("; // build the description from the extension list Enumeration extensions = filters.keys(); if (extensions != null) { fullDescription += "." + (String) extensions.nextElement(); while (extensions.hasMoreElements()) { fullDescription += ", ." + (String) extensions.nextElement(); } } fullDescription += ")"; } else { fullDescription = description; } } return fullDescription; } /** * Sets the human readable description of this filter. For example: * filter.setDescription("Gif and JPG Images"); * */ public void setDescription(String description) { this.description = description; fullDescription = null; } /** * Determines whether the extension list (.jpg, .gif, etc) should show up in * the human readable description. * * Only relevent if a description was provided in the constructor or using * setDescription(); * */ public void setExtensionListInDescription(boolean b) { useExtensionsInDescription = b; fullDescription = null; } /** * Returns whether the extension list (.jpg, .gif, etc) should show up in * the human readable description. * * Only relevent if a description was provided in the constructor or using * setDescription(); * */ public boolean isExtensionListInDescription() { return useExtensionsInDescription; } }