/*
* Copyright 2002-2007 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 org.springframework.core;
import java.util.Comparator;
/**
* {@link Comparator} implementation for {@link Ordered} objects,
* sorting by order value ascending (resp. by priority descending).
*
* <p>Non-<code>Ordered</code> objects are treated as greatest order
* values, thus ending up at the end of the list, in arbitrary order
* (just like same order values of <code>Ordered</code> objects).
*
* @author Juergen Hoeller
* @since 07.04.2003
* @see Ordered
* @see java.util.Collections#sort(java.util.List, java.util.Comparator)
* @see java.util.Arrays#sort(Object[], java.util.Comparator)
*/
public class OrderComparator implements Comparator {
public int compare(Object o1, Object o2) {
boolean p1 = (o1 instanceof PriorityOrdered);
boolean p2 = (o2 instanceof PriorityOrdered);
if (p1 && !p2) {
return -1;
}
else if (p2 && !p1) {
return 1;
}
// Direct evaluation instead of Integer.compareTo to avoid unnecessary object creation.
int i1 = getOrder(o1);
int i2 = getOrder(o2);
return (i1 < i2) ? -1 : (i1 > i2) ? 1 : 0;
}
/**
* Determine the order value for the given object.
* <p>The default implementation checks against the {@link Ordered}
* interface. Can be overridden in subclasses.
* @param obj the object to check
* @return the order value, or <code>Ordered.LOWEST_PRECEDENCE</code> as fallback
*/
protected int getOrder(Object obj) {
return (obj instanceof Ordered ? ((Ordered) obj).getOrder() : Ordered.LOWEST_PRECEDENCE);
}
}