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 }