java、scala集合自定义排序异常：Comparison method violates its general contract!

cala 集合（array，seq）排序报错

User class threw exception: org.apache.spark.SparkException: Job aborted due to stage failure: Task 43 in stage 3.0 failed 4 times, most recent failure: Lost task 43.3 in stage 3.0 (TID 1479, node9): java.lang.IllegalArgumentException: Comparison method violates
its general contract!

at java.util.TimSort.mergeHi(TimSort.java:868)

at java.util.TimSort.mergeAt(TimSort.java:485)

at java.util.TimSort.mergeCollapse(TimSort.java:408)

at java.util.TimSort.sort(TimSort.java:214)

at java.util.TimSort.sort(TimSort.java:173)

at java.util.Arrays.sort(Arrays.java:659)

at scala.collection.SeqLike$class.sorted(SeqLike.scala:615)

at scala.collection.AbstractSeq.sorted(Seq.scala:40)

at scala.collection.SeqLike$class.sortWith(SeqLike.scala:572)

at scala.collection.AbstractSeq.sortWith(Seq.scala:40)

at com.wk.dict.seo.SupplyAggregation$$anonfun$2$$anonfun$apply$4.apply(SupplyAggregation.scala:40)

at com.wk.dict.seo.SupplyAggregation$$anonfun$2$$anonfun$apply$4.apply(SupplyAggregation.scala:39)

at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)

at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
代码：

val supplyKeywordsSort = supplyKeywords.sortWith((a, b) => {
var flag = true
val i = a._3 - b._3
if (i > 0) {
flag = false
} else if (i == 0) {
val j = a._4 - b._4
if (j > 0) {
flag = false
}
}
flag
})
原因：底层的排序算法TimSort，如果两个元素相等，返回为true的话，就会报该异常Comparison method violates its general contract!
解决办法：将相等的时候设为false

val supplyKeywordsSort = supplyKeywords.sortWith((a, b) => {
var flag = true
val i = a._3 - b._3
if (i > 0) {
flag = false
} else if (i == 0) {
val j = a._4 - b._4
if (j >= 0) {
flag = false
}
}
flag
})