001    /*
002     * Copyright (c) 2007-2015 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 Min is an {@link cascading.operation.Aggregator} that returns the minimum value encountered in the current group.
029     * <p/>
030     * As opposed to the {@link Min} class, values are expected to be {@link Comparable} types vs numeric representations and
031     * the {@link Comparable#compareTo(Object)} result is use for min comparison.
032     */
033    public class MinValue extends ExtremaValueBase
034      {
035      /** Field FIELD_NAME */
036      public static final String FIELD_NAME = "min";
037    
038      /** Constructs a new instance that returns the Min value encountered in the field name "min". */
039      public MinValue()
040        {
041        super( 1, new Fields( FIELD_NAME ) );
042        }
043    
044      /**
045       * Constructs a new instance that returns the minimum value encountered in the given fieldDeclaration field name.
046       *
047       * @param fieldDeclaration of type Fields
048       */
049      @ConstructorProperties({"fieldDeclaration"})
050      public MinValue( Fields fieldDeclaration )
051        {
052        super( 1, fieldDeclaration );
053        }
054    
055      /**
056       * Constructs a new instance that returns the minimum value encountered in the given fieldDeclaration field name.
057       * Any argument matching an ignoredValue won't be compared.
058       *
059       * @param fieldDeclaration of type Fields
060       * @param ignoreValues     of type Object...
061       */
062      @ConstructorProperties({"fieldDeclaration", "ignoreValues"})
063      public MinValue( Fields fieldDeclaration, Object... ignoreValues )
064        {
065        super( fieldDeclaration, ignoreValues );
066        }
067    
068      @Override
069      protected boolean compare( Comparable lhs, Comparable rhs )
070        {
071        return lhs.compareTo( rhs ) > 0;
072        }
073      }