ByItemIDComparator.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.mahout.cf.taste.hadoop.slopeone;

import java.io.Serializable;
import java.util.Comparator;

import org.apache.mahout.cf.taste.hadoop.EntityPrefWritable;

final class ByItemIDComparator implements Comparator<EntityPrefWritable>, Serializable {
  
  private static final Comparator<EntityPrefWritable> INSTANCE = new ByItemIDComparator();
  
  public static Comparator<EntityPrefWritable> getInstance() {
    return INSTANCE;
  }
  
  @Override
  public int compare(EntityPrefWritable a, EntityPrefWritable b) {
    long idA = a.getID();
    long idB = b.getID();
    return idA < idB ? -1 : idA > idB ? 1 : 0;
  }
  
}