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.util; 022 023 import java.io.Serializable; 024 import java.util.Comparator; 025 026 /** 027 * Class NullNotEquivalentComparator simply returns -1 if the lhs is null, 1 if the rhs is null, or 028 * the result of {@code lhs.compareTo(rhs)}. 029 * <p/> 030 * Use this {@link Comparator} when performing a {@link cascading.pipe.CoGroup} that needs SQL like semantics. 031 */ 032 public class NullNotEquivalentComparator implements Comparator<Comparable>, Serializable 033 { 034 @Override 035 public int compare( Comparable lhs, Comparable rhs ) 036 { 037 if( lhs == null ) 038 return -1; 039 040 if( rhs == null ) 041 return 1; 042 043 return lhs.compareTo( rhs ); 044 } 045 }