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Google Collections Library is a suite of new collections and collection-related goodness for Java 5.0
/*
* Copyright (C) 2007 Google Inc.
*
* 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 com.google.common.collect;
import com.google.common.annotations.GwtCompatible;
import static com.google.common.base.Preconditions.checkNotNull;
import java.io.Serializable;
import java.util.Collections;
import java.util.List;
/** An ordering that uses the natural order of the values. */
@GwtCompatible(serializable = true)
@SuppressWarnings("unchecked") // TODO: the right way to explain this??
final class NaturalOrdering
extends Ordering implements Serializable {
static final NaturalOrdering INSTANCE = new NaturalOrdering();
public int compare(Comparable left, Comparable right) {
checkNotNull(right); // left null is caught later
if (left == right) {
return 0;
}
@SuppressWarnings("unchecked") // we're permitted to throw CCE
int result = left.compareTo(right);
return result;
}
@SuppressWarnings("unchecked") // TODO: the right way to explain this??
@Override public Ordering reverse() {
return (Ordering) ReverseNaturalOrdering.INSTANCE;
}
// Override to remove a level of indirection from inner loop
@SuppressWarnings("unchecked") // TODO: the right way to explain this??
@Override public int binarySearch(
List sortedList, Comparable key) {
return Collections.binarySearch((List) sortedList, key);
}
// Override to remove a level of indirection from inner loop
@Override public List sortedCopy(
Iterable iterable) {
List list = Lists.newArrayList(iterable);
Collections.sort(list);
return list;
}
// preserving singleton-ness gives equals()/hashCode() for free
private Object readResolve() {
return INSTANCE;
}
@Override public String toString() {
return "Ordering.natural()";
}
private NaturalOrdering() {}
private static final long serialVersionUID = 0;
}