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.util; 023 024import java.io.Serializable; 025import java.util.Comparator; 026 027/** 028 * Class NullNotEquivalentComparator simply returns -1 if the lhs is null, 1 if the rhs is null, or 029 * the result of {@code lhs.compareTo(rhs)}. 030 * <p> 031 * Use this {@link Comparator} when performing a {@link cascading.pipe.CoGroup} that needs SQL like semantics. 032 */ 033public class NullNotEquivalentComparator implements Comparator<Comparable>, Serializable 034 { 035 @Override 036 public int compare( Comparable lhs, Comparable rhs ) 037 { 038 if( lhs == null ) 039 return -1; 040 041 if( rhs == null ) 042 return 1; 043 044 return lhs.compareTo( rhs ); 045 } 046 }