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	/*
	* 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()) + "]";
	}
	}

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