/*
* Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package javax.swing.filechooser;
import java.io.File;
import java.util.Locale;
/**
* An implementation of {@code FileFilter} that filters using a
* specified set of extensions. The extension for a file is the
* portion of the file name after the last ".". Files whose name does
* not contain a "." have no file name extension. File name extension
* comparisons are case insensitive.
* <p>
* The following example creates a
* {@code FileNameExtensionFilter} that will show {@code jpg} files:
* <pre>
* FileFilter filter = new FileNameExtensionFilter("JPEG file", "jpg", "jpeg");
* JFileChooser fileChooser = ...;
* fileChooser.addChoosableFileFilter(filter);
* </pre>
*
* @see FileFilter
* @see javax.swing.JFileChooser#setFileFilter
* @see javax.swing.JFileChooser#addChoosableFileFilter
* @see javax.swing.JFileChooser#getFileFilter
*
* @since 1.6
*/
public final class FileNameExtensionFilter extends FileFilter {
// Description of this filter.
private final String description;
// Known extensions.
private final String[] extensions;
// Cached ext
private final String[] lowerCaseExtensions;
/**
* Creates a {@code FileNameExtensionFilter} with the specified
* description and file name extensions. The returned {@code
* FileNameExtensionFilter} will accept all directories and any
* file with a file name extension contained in {@code extensions}.
*
* @param description textual description for the filter, may be
* {@code null}
* @param extensions the accepted file name extensions
* @throws IllegalArgumentException if extensions is {@code null}, empty,
* contains {@code null}, or contains an empty string
* @see #accept
*/
public FileNameExtensionFilter(String description, String... extensions) {
if (extensions == null || extensions.length == 0) {
throw new IllegalArgumentException(
"Extensions must be non-null and not empty");
}
this.description = description;
this.extensions = new String[extensions.length];
this.lowerCaseExtensions = new String[extensions.length];
for (int i = 0; i < extensions.length; i++) {
if (extensions[i] == null || extensions[i].length() == 0) {
throw new IllegalArgumentException(
"Each extension must be non-null and not empty");
}
this.extensions[i] = extensions[i];
lowerCaseExtensions[i] = extensions[i].toLowerCase(Locale.ENGLISH);
}
}
/**
* Tests the specified file, returning true if the file is
* accepted, false otherwise. True is returned if the extension
* matches one of the file name extensions of this {@code
* FileFilter}, or the file is a directory.
*
* @param f the {@code File} to test
* @return true if the file is to be accepted, false otherwise
*/
public boolean accept(File f) {
if (f != null) {
if (f.isDirectory()) {
return true;
}
// NOTE: we tested implementations using Maps, binary search
// on a sorted list and this implementation. All implementations
// provided roughly the same speed, most likely because of
// overhead associated with java.io.File. Therefor we've stuck
// with the simple lightweight approach.
String fileName = f.getName();
int i = fileName.lastIndexOf('.');
if (i > 0 && i < fileName.length() - 1) {
String desiredExtension = fileName.substring(i+1).
toLowerCase(Locale.ENGLISH);
for (String extension : lowerCaseExtensions) {
if (desiredExtension.equals(extension)) {
return true;
}
}
}
}
return false;
}
/**
* The description of this filter. For example: "JPG and GIF Images."
*
* @return the description of this filter
*/
public String getDescription() {
return description;
}
/**
* Returns the set of file name extensions files are tested against.
*
* @return the set of file name extensions files are tested against
*/
public String[] getExtensions() {
String[] result = new String[extensions.length];
System.arraycopy(extensions, 0, result, 0, extensions.length);
return result;
}
/**
* Returns a string representation of the {@code FileNameExtensionFilter}.
* This method is intended to be used for debugging purposes,
* and the content and format of the returned string may vary
* between implementations.
*
* @return a string representation of this {@code FileNameExtensionFilter}
*/
public String toString() {
return super.toString() + "[description=" + getDescription() +
" extensions=" + java.util.Arrays.asList(getExtensions()) + "]";
}
}