From 8113855b3af913e6dcd09626953c64d43168efbd Mon Sep 17 00:00:00 2001
From: Yongjun Zhang <yzhang@cloudera.com>
Date: Tue, 28 Jun 2016 23:15:13 -0700
Subject: [PATCH] HDFS-10396. Using -diff option with DistCp may get
 "Comparison method violates its general contract" exception. Contributed by
 Yongjun Zhang.

---
 .../src/main/java/org/apache/hadoop/tools/DiffInfo.java       | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hadoop-tools/hadoop-distcp/src/main/java/org/apache/hadoop/tools/DiffInfo.java b/hadoop-tools/hadoop-distcp/src/main/java/org/apache/hadoop/tools/DiffInfo.java
index 10a8b7e25c2..79bb7fe2671 100644
--- a/hadoop-tools/hadoop-distcp/src/main/java/org/apache/hadoop/tools/DiffInfo.java
+++ b/hadoop-tools/hadoop-distcp/src/main/java/org/apache/hadoop/tools/DiffInfo.java
@@ -38,8 +38,8 @@ class DiffInfo {
   static final Comparator<DiffInfo> targetComparator = new Comparator<DiffInfo>() {
     @Override
     public int compare(DiffInfo d1, DiffInfo d2) {
-      return d1.target == null ? -1 :
-          (d2.target ==  null ? 1 : d1.target.compareTo(d2.target));
+      return d1.target == null ? ((d2.target == null)? 0 : -1) :
+        (d2.target ==  null ? 1 : d1.target.compareTo(d2.target));
     }
   };