org.codelibs.elasticsearch.taste.recommender.GenericRecommendedItem Maven / Gradle / Ivy

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/**
 * 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.codelibs.elasticsearch.taste.recommender;

import java.io.Serializable;

import org.apache.mahout.common.RandomUtils;

import com.google.common.base.Preconditions;

/**
 * 
 * A simple implementation of {@link RecommendedItem}.
 * 
 */
public final class GenericRecommendedItem implements RecommendedItem,
        Serializable {

    /**
     *
     */
    private static final long serialVersionUID = 1L;

    private final long itemID;

    private final float value;

    /**
     * @throws IllegalArgumentException
     *           if item is null or value is NaN
     */
    public GenericRecommendedItem(final long itemID, final float value) {
        Preconditions.checkArgument(!Float.isNaN(value), "value is NaN");
        this.itemID = itemID;
        this.value = value;
    }

    @Override
    public long getItemID() {
        return itemID;
    }

    @Override
    public float getValue() {
        return value;
    }

    @Override
    public String toString() {
        return "RecommendedItem[item:" + itemID + ", value:" + value + ']';
    }

    @Override
    public int hashCode() {
        return (int) itemID ^ RandomUtils.hashFloat(value);
    }

    @Override
    public boolean equals(final Object o) {
        if (!(o instanceof GenericRecommendedItem)) {
            return false;
        }
        final RecommendedItem other = (RecommendedItem) o;
        return itemID == other.getItemID() && value == other.getValue();
    }

}