001/* 002 * Copyright (c) 2016-2017 Chris K Wensel <chris@wensel.net>. All Rights Reserved. 003 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved. 004 * 005 * Project and contact information: http://www.cascading.org/ 006 * 007 * This file is part of the Cascading project. 008 * 009 * Licensed under the Apache License, Version 2.0 (the "License"); 010 * you may not use this file except in compliance with the License. 011 * You may obtain a copy of the License at 012 * 013 * http://www.apache.org/licenses/LICENSE-2.0 014 * 015 * Unless required by applicable law or agreed to in writing, software 016 * distributed under the License is distributed on an "AS IS" BASIS, 017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 018 * See the License for the specific language governing permissions and 019 * limitations under the License. 020 */ 021 022package cascading.operation.aggregator; 023 024import java.beans.ConstructorProperties; 025 026import cascading.tuple.Fields; 027 028/** 029 * Class MaxValue is an {@link cascading.operation.Aggregator} that returns the maximum value encountered in the 030 * current group. 031 * <p> 032 * Values are expected to be {@link Comparable} types vs numeric representations and 033 * the {@link Comparable#compareTo(Object)} result is use for max comparison. 034 */ 035public class MaxValue extends ExtremaValueBase 036 { 037 /** Field FIELD_NAME */ 038 public static final String FIELD_NAME = "max"; 039 040 /** Constructs a new instance that returns the maximum value encountered in the field name "max". */ 041 public MaxValue() 042 { 043 super( 1, new Fields( FIELD_NAME ) ); 044 } 045 046 /** 047 * Constructs a new instance that returns the maximum value encountered in the given fieldDeclaration field name. 048 * 049 * @param fieldDeclaration of type Fields 050 */ 051 @ConstructorProperties({"fieldDeclaration"}) 052 public MaxValue( Fields fieldDeclaration ) 053 { 054 super( 1, fieldDeclaration ); 055 } 056 057 /** 058 * Constructs a new instance that returns the maximum value encountered in the given fieldDeclaration field name. 059 * Any argument matching an ignoredValue won't be compared. 060 * 061 * @param fieldDeclaration of type Fields 062 * @param ignoreValues of type Object... 063 */ 064 @ConstructorProperties({"fieldDeclaration", "ignoreValues"}) 065 public MaxValue( Fields fieldDeclaration, Object... ignoreValues ) 066 { 067 super( fieldDeclaration, ignoreValues ); 068 } 069 070 @Override 071 protected boolean compare( Comparable lhs, Comparable rhs ) 072 { 073 return lhs.compareTo( rhs ) < 0; 074 } 075 }