leap.lang.io.IOComparators Maven / Gradle / Ivy
/*
* Copyright 2012 the original author or authors.
*
* Licensed 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 leap.lang.io;
import java.io.File;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
public class IOComparators {
/** Case-sensitive name comparator instance (see {@link IOCase#SENSITIVE}) */
private static final Comparator NAME_COMPARATOR = new NameFileComparator();
/** Reverse case-sensitive name comparator instance (see {@link IOCase#SENSITIVE}) */
private static final Comparator NAME_REVERSE = new ReverseComparator(NAME_COMPARATOR);
/** Case-insensitive name comparator instance (see {@link IOCase#INSENSITIVE}) */
private static final Comparator NAME_INSENSITIVE_COMPARATOR = new NameFileComparator(IOCase.INSENSITIVE);
/** Reverse case-insensitive name comparator instance (see {@link IOCase#INSENSITIVE}) */
private static final Comparator NAME_INSENSITIVE_REVERSE = new ReverseComparator(NAME_INSENSITIVE_COMPARATOR);
/** System sensitive name comparator instance (see {@link IOCase#SYSTEM}) */
private static final Comparator NAME_SYSTEM_COMPARATOR = new NameFileComparator(IOCase.SYSTEM);
/** Reverse system sensitive name comparator instance (see {@link IOCase#SYSTEM}) */
private static final Comparator NAME_SYSTEM_REVERSE = new ReverseComparator(NAME_SYSTEM_COMPARATOR);
public static Comparator nameSensitive(){
return NAME_COMPARATOR;
}
public static Comparator nameSensitiveReverse(){
return NAME_REVERSE;
}
public static Comparator nameInsensitive(){
return NAME_INSENSITIVE_COMPARATOR;
}
public static Comparator nameInsensitiveReverse(){
return NAME_INSENSITIVE_REVERSE;
}
public static Comparator nameSystem(){
return NAME_SYSTEM_COMPARATOR;
}
public static Comparator nameSystemReverse(){
return NAME_SYSTEM_REVERSE;
}
/**
* Compare the names of two files for order (see {@link File#getName()}).
*
* This comparator can be used to sort lists or arrays of files
* by their name either in a case-sensitive, case-insensitive or
* system dependant case sensitive way. A number of singleton instances
* are provided for the various case sensitivity options (using {@link IOCase})
* and the reverse of those options.
*
* Example of a case-sensitive file name sort using the
* {@link #NAME_COMPARATOR} singleton instance:
*
* List<File> list = ...
* NameFileComparator.NAME_COMPARATOR.sort(list);
*
*
* Example of a reverse case-insensitive file name sort using the
* {@link #NAME_INSENSITIVE_REVERSE} singleton instance:
*
* File[] array = ...
* NameFileComparator.NAME_INSENSITIVE_REVERSE.sort(array);
*
*
*/
static class NameFileComparator extends AbstractFileComparator {
/** Whether the comparison is case sensitive. */
private final IOCase caseSensitivity;
/**
* Construct a case sensitive file name comparator instance.
*/
public NameFileComparator() {
this.caseSensitivity = IOCase.SENSITIVE;
}
/**
* Construct a file name comparator instance with the specified case-sensitivity.
*
* @param caseSensitivity how to handle case sensitivity, null means case-sensitive
*/
public NameFileComparator(IOCase caseSensitivity) {
this.caseSensitivity = caseSensitivity == null ? IOCase.SENSITIVE : caseSensitivity;
}
/**
* Compare the names of two files with the specified case sensitivity.
*
* @param file1 The first file to compare
* @param file2 The second file to compare
* @return a negative value if the first file's name
* is less than the second, zero if the names are the
* same and a positive value if the first files name
* is greater than the second file.
*/
public int compare(File file1, File file2) {
return caseSensitivity.checkCompareTo(file1.getName(), file2.getName());
}
/**
* String representation of this file comparator.
*
* @return String representation of this file comparator
*/
@Override
public String toString() {
return super.toString() + "[caseSensitivity=" + caseSensitivity + "]";
}
}
static class ReverseComparator extends AbstractFileComparator {
private final Comparator delegate;
public ReverseComparator(Comparator delegate) {
if (delegate == null) {
throw new IllegalArgumentException("Delegate comparator is missing");
}
this.delegate = delegate;
}
public int compare(File file1, File file2) {
return delegate.compare(file2, file1); // parameters switched round
}
@Override
public String toString() {
return super.toString() + "[" + delegate.toString() + "]";
}
}
static abstract class AbstractFileComparator implements Comparator {
public File[] sort(File... files) {
if (files != null) {
Arrays.sort(files, this);
}
return files;
}
public List sort(List files) {
if (files != null) {
Collections.sort(files, this);
}
return files;
}
@Override
public String toString() {
return getClass().getSimpleName();
}
}
}