1 /* 2 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package javax.swing.filechooser; 27 28 import java.io.File; 29 import java.util.Locale; 30 31 /** 32 * An implementation of {@code FileFilter} that filters using a 33 * specified set of extensions. The extension for a file is the 34 * portion of the file name after the last ".". Files whose name does 35 * not contain a "." have no file name extension. File name extension 36 * comparisons are case insensitive. 37 * <p> 38 * The following example creates a 39 * {@code FileNameExtensionFilter} that will show {@code jpg} files: 40 * <pre> 41 * FileFilter filter = new FileNameExtensionFilter("JPEG file", "jpg", "jpeg"); 42 * JFileChooser fileChooser = ...; 43 * fileChooser.addChoosableFileFilter(filter); 44 * </pre> 45 * 46 * @see FileFilter 47 * @see javax.swing.JFileChooser#setFileFilter 48 * @see javax.swing.JFileChooser#addChoosableFileFilter 49 * @see javax.swing.JFileChooser#getFileFilter 50 * 51 * @since 1.6 52 */ 53 public final class FileNameExtensionFilter extends FileFilter { 54 // Description of this filter. 55 private final String description; 56 // Known extensions. 57 private final String[] extensions; 58 // Cached ext 59 private final String[] lowerCaseExtensions; 60 61 /** 62 * Creates a {@code FileNameExtensionFilter} with the specified 63 * description and file name extensions. The returned {@code 64 * FileNameExtensionFilter} will accept all directories and any 65 * file with a file name extension contained in {@code extensions}. 66 * 67 * @param description textual description for the filter, may be 68 * {@code null} 69 * @param extensions the accepted file name extensions 70 * @throws IllegalArgumentException if extensions is {@code null}, empty, 71 * contains {@code null}, or contains an empty string 72 * @see #accept 73 */ FileNameExtensionFilter(String description, String... extensions)74 public FileNameExtensionFilter(String description, String... extensions) { 75 if (extensions == null || extensions.length == 0) { 76 throw new IllegalArgumentException( 77 "Extensions must be non-null and not empty"); 78 } 79 this.description = description; 80 this.extensions = new String[extensions.length]; 81 this.lowerCaseExtensions = new String[extensions.length]; 82 for (int i = 0; i < extensions.length; i++) { 83 if (extensions[i] == null || extensions[i].length() == 0) { 84 throw new IllegalArgumentException( 85 "Each extension must be non-null and not empty"); 86 } 87 this.extensions[i] = extensions[i]; 88 lowerCaseExtensions[i] = extensions[i].toLowerCase(Locale.ENGLISH); 89 } 90 } 91 92 /** 93 * Tests the specified file, returning true if the file is 94 * accepted, false otherwise. True is returned if the extension 95 * matches one of the file name extensions of this {@code 96 * FileFilter}, or the file is a directory. 97 * 98 * @param f the {@code File} to test 99 * @return true if the file is to be accepted, false otherwise 100 */ accept(File f)101 public boolean accept(File f) { 102 if (f != null) { 103 if (f.isDirectory()) { 104 return true; 105 } 106 // NOTE: we tested implementations using Maps, binary search 107 // on a sorted list and this implementation. All implementations 108 // provided roughly the same speed, most likely because of 109 // overhead associated with java.io.File. Therefor we've stuck 110 // with the simple lightweight approach. 111 String fileName = f.getName(); 112 int i = fileName.lastIndexOf('.'); 113 if (i > 0 && i < fileName.length() - 1) { 114 String desiredExtension = fileName.substring(i+1). 115 toLowerCase(Locale.ENGLISH); 116 for (String extension : lowerCaseExtensions) { 117 if (desiredExtension.equals(extension)) { 118 return true; 119 } 120 } 121 } 122 } 123 return false; 124 } 125 126 /** 127 * The description of this filter. For example: "JPG and GIF Images." 128 * 129 * @return the description of this filter 130 */ getDescription()131 public String getDescription() { 132 return description; 133 } 134 135 /** 136 * Returns the set of file name extensions files are tested against. 137 * 138 * @return the set of file name extensions files are tested against 139 */ getExtensions()140 public String[] getExtensions() { 141 String[] result = new String[extensions.length]; 142 System.arraycopy(extensions, 0, result, 0, extensions.length); 143 return result; 144 } 145 146 /** 147 * Returns a string representation of the {@code FileNameExtensionFilter}. 148 * This method is intended to be used for debugging purposes, 149 * and the content and format of the returned string may vary 150 * between implementations. 151 * 152 * @return a string representation of this {@code FileNameExtensionFilter} 153 */ toString()154 public String toString() { 155 return super.toString() + "[description=" + getDescription() + 156 " extensions=" + java.util.Arrays.asList(getExtensions()) + "]"; 157 } 158 } 159