/*
* Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*/
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()) + "]";
}
}