    001    /*
    002     * Copyright (c) 2007-2014 Concurrent, Inc. All Rights Reserved.
    003     *
    004     * Project and contact information: http://www.cascading.org/
    005     *
    006     * This file is part of the Cascading project.
    007     *
    008     * Licensed under the Apache License, Version 2.0 (the "License");
    009     * you may not use this file except in compliance with the License.
    010     * You may obtain a copy of the License at
    011     *
    012     *     http://www.apache.org/licenses/LICENSE-2.0
    013     *
    014     * Unless required by applicable law or agreed to in writing, software
    015     * distributed under the License is distributed on an "AS IS" BASIS,
    016     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    017     * See the License for the specific language governing permissions and
    018     * limitations under the License.
    019     */
    020
    021    package cascading.operation.aggregator;
    022
    023    import java.beans.ConstructorProperties;
    024
    025    import cascading.tuple.Fields;
    026
    027    /**
    028     * Class MaxValue is an {@link cascading.operation.Aggregator} that returns the maximum value encountered in the
    029     * current group.
    030     * <p/>
    031     * As opposed to the {@link Max} class, values are expected to be {@link Comparable} types vs numeric representations and
    032     * the {@link Comparable#compareTo(Object)} result is use for max comparison.
    033     */
    034    public class MaxValue extends ExtremaValueBase
    035      {
    036      /** Field FIELD_NAME */
    037      public static final String FIELD_NAME = "max";
    038
    039      /** Constructs a new instance that returns the maximum value encountered in the field name "max". */
    040      public MaxValue()
    041        {
    042        super( 1, new Fields( FIELD_NAME ) );
    043        }
    044
    045      /**
    046       * Constructs a new instance that returns the maximum value encountered in the given fieldDeclaration field name.
    047       *
    048       * @param fieldDeclaration of type Fields
    049       */
    050      @ConstructorProperties({"fieldDeclaration"})
    051      public MaxValue( Fields fieldDeclaration )
    052        {
    053        super( 1, fieldDeclaration );
    054        }
    055
    056      /**
    057       * Constructs a new instance that returns the maximum value encountered in the given fieldDeclaration field name.
    058       * Any argument matching an ignoredValue won't be compared.
    059       *
    060       * @param fieldDeclaration of type Fields
    061       * @param ignoreValues     of type Object...
    062       */
    063      @ConstructorProperties({"fieldDeclaration", "ignoreValues"})
    064      public MaxValue( Fields fieldDeclaration, Object... ignoreValues )
    065        {
    066        super( fieldDeclaration, ignoreValues );
    067        }
    068
    069      @Override
    070      protected boolean compare( Comparable lhs, Comparable rhs )
    071        {
    072        return lhs.compareTo( rhs ) < 0;
    073        }
    074      }