craterdog.utils.NaturalComparator Maven / Gradle / Ivy
/************************************************************************
* Copyright (c) Crater Dog Technologies(TM). 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 MIT License (MIT), as published by the Open *
* Source Initiative. (See http://opensource.org/licenses/MIT) *
************************************************************************/
package craterdog.utils;
import java.util.Comparator;
/**
* This class defines a comparator that compares two objects of the same type using their natural
* compareTo method if the type implements the Comparable interface, or
* by doing a lexical comparison on their string formats if not. This comparator handles
* null values as well. A null value is always less than an non
* null value and two null values are equal.
*
* @author Derk Norton
* @param The type of the objects being compared.
*/
public class NaturalComparator implements Comparator {
@Override
public int compare(T object1, T object2) {
if (object1 != null) {
if (object2 == null) return 1; // the second object is null
if (object1 instanceof Comparable) {
// use the natural ordering
@SuppressWarnings("unchecked")
Comparable comparable1 = (Comparable) object1;
return comparable1.compareTo(object2);
} else if (object1.getClass().isArray()) {
// compare the elements in the arrays
Object[] array1 = (Object[]) object1;
Object[] array2 = (Object[]) object2;
return compareArrays(array1, array2);
} else {
// use lexical ordering
String string1 = object1.toString();
String string2 = object2.toString();
return string1.compareTo(string2);
}
}
if (object2 != null) {
return -1; // first object is null
}
return 0; // both objects are null
}
static private int compareArrays(Object[] array1, Object[] array2) {
Comparator