com.signalfx.shaded.apache.commons.io.filefilter.EmptyFileFilter Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.signalfx.shaded.apache.commons.io.filefilter;
import java.io.File;
import java.io.Serializable;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.stream.Stream;
import com.signalfx.shaded.apache.commons.io.IOUtils;
/**
* This filter accepts files or directories that are empty.
*
* If the {@link File} is a directory it checks that it contains no files.
*
*
* Example, showing how to print out a list of the current directory's empty files/directories:
*
* Using Classic IO
*
* File dir = FileUtils.current();
* String[] files = dir.list(EmptyFileFilter.EMPTY);
* for (String file : files) {
* System.out.println(file);
* }
*
*
*
* Example, showing how to print out a list of the current directory's non-empty files/directories:
*
*
*
* File dir = FileUtils.current();
* String[] files = dir.list(EmptyFileFilter.NOT_EMPTY);
* for (String file : files) {
* System.out.println(file);
* }
*
*
* Using NIO
*
* final Path dir = PathUtils.current();
* final AccumulatorPathVisitor visitor = AccumulatorPathVisitor.withLongCounters(EmptyFileFilter.EMPTY);
* //
* // Walk one dir
* Files.walkFileTree(dir, Collections.emptySet(), 1, visitor);
* System.out.println(visitor.getPathCounters());
* System.out.println(visitor.getFileList());
* //
* visitor.getPathCounters().reset();
* //
* // Walk dir tree
* Files.walkFileTree(dir, visitor);
* System.out.println(visitor.getPathCounters());
* System.out.println(visitor.getDirList());
* System.out.println(visitor.getFileList());
*
* Deprecating Serialization
*
* Serialization is deprecated and will be removed in 3.0.
*
*
* @since 1.3
*/
public class EmptyFileFilter extends AbstractFileFilter implements Serializable {
/** Singleton instance of empty filter */
public static final IOFileFilter EMPTY = new EmptyFileFilter();
/** Singleton instance of not-empty filter */
public static final IOFileFilter NOT_EMPTY = EMPTY.negate();
private static final long serialVersionUID = 3631422087512832211L;
/**
* Restrictive constructor.
*/
protected EmptyFileFilter() {
}
/**
* Checks to see if the file is empty.
*
* @param file the file or directory to check
* @return {@code true} if the file or directory is empty, otherwise {@code false}.
*/
@Override
public boolean accept(final File file) {
if (file.isDirectory()) {
final File[] files = file.listFiles();
return IOUtils.length(files) == 0;
}
return file.length() == 0;
}
/**
* Checks to see if the file is empty.
* @param file the file or directory to check
*
* @return {@code true} if the file or directory is empty, otherwise {@code false}.
* @since 2.9.0
*/
@Override
public FileVisitResult accept(final Path file, final BasicFileAttributes attributes) {
return get(() -> {
if (Files.isDirectory(file)) {
try (Stream stream = Files.list(file)) {
return toFileVisitResult(!stream.findFirst().isPresent());
}
}
return toFileVisitResult(Files.size(file) == 0);
});
}
}