/*
* Copyright (C) 2007 The Guava 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 com.google.common.collect;
import static com.google.common.base.
Preconditions.checkNotNull;
import com.google.common.annotations.
GwtCompatible;
import java.io.
Serializable;
/** An ordering that uses the natural order of the values. */
@
GwtCompatible(serializable = true)
@
SuppressWarnings("unchecked") // TODO(kevinb): the right way to explain this??
final class
NaturalOrdering
extends
Ordering<
Comparable> implements
Serializable {
static final
NaturalOrdering INSTANCE = new
NaturalOrdering();
@
Override public int
compare(
Comparable left,
Comparable right) {
checkNotNull(
left); // for GWT
checkNotNull(
right);
return
left.
compareTo(
right);
}
@
Override public <S extends
Comparable>
Ordering<S>
reverse() {
return (
Ordering<S>)
ReverseNaturalOrdering.
INSTANCE;
}
// 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;
}