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 021package cascading.operation.aggregator; 022 023import java.beans.ConstructorProperties; 024 025import 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 * 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 */ 033public 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 }