我正在测试一些哈希映射相等的代码，
我重写hashCode，equals以及超级和子类的canEqual，但为什么它会继续抛出匹配错误？
测试代码如下：
object ObjEqualExam {
case class TestClassKey(s: String, i:Int) {
def str = s
def in = i
override def equals (other : Any) = other match {
case that : TestClassKey => (that canEqual this ) && (this.str == that.str) && (this.in == that.in)
}
override def hashCode = 41* (41 + in) + in
override def canEqual(other : Any) = other.isInstanceOf[TestClassKey]
}
case class SubTestClassKey(ss: String, ii: Int, b : Boolean) extends TestClassKey(ss,ii){
def bool = b
override def equals (other : Any) = other match {
case that : SubTestClassKey =>
(that canEqual this ) && (this.str == that.str) && (this.in == that.in) && (this.b == that.b)
}
override def hashCode = 41* (41 + in) * in
override def canEqual(other : Any) = other.isInstanceOf[SubTestClassKey]
}
def main(args: Array[String]): Unit = {
val map = Map.empty[TestClassKey, Int]
val ins = new TestClassKey("1", 1)
val map2 = map ++ List((ins->100), (new TestClassKey("2", 2)->200), (new SubTestClassKey("3", 3, true) -> 300))
val map22 = Map.empty
val ins22 = new TestClassKey("1", 1)
val map222 = map ++ List((ins->100), (new TestClassKey("2", 2)->200), (new SubTestClassKey("3", 3, true) -> 300))
println(map2 == map222)
}
}
错误如下：
Exception in thread "main" scala.MatchError: TestClassKey(1,1) (of class org.tests.ObjEqualExam$TestClassKey)
at org.tests.ObjEqualExam$SubTestClassKey.equals(ObjEqualExam.scala:18)
at scala.collection.immutable.Map$Map2.updated(Map.scala:131)
at scala.collection.immutable.Map$Map2.$plus(Map.scala:134)
at scala.collection.immutable.MapLike$$anonfun$$plus$plus$1.apply(MapLike.scala:87)
at scala.collection.immutable.MapLike$$anonfun$$plus$plus$1.apply(MapLike.scala:87)
at scala.collection.LinearSeqOptimized$class.foldLeft(LinearSeqOptimized.scala:111)
at scala.collection.immutable.List.foldLeft(List.scala:76)
at scala.collection.TraversableOnce$class.$div$colon(TraversableOnce.scala:137)
at scala.collection.immutable.List.$div$colon(List.scala:76)
at scala.collection.immutable.MapLike$class.$plus$plus(MapLike.scala:87)
at scala.collection.immutable.Map$EmptyMap$.$plus$plus(Map.scala:88)
at org.tests.ObjEqualExam$.main(ObjEqualExam.scala:29)
at org.tests.ObjEqualExam.main(ObjEqualExam.scala)
（是因为某些协变或逆变还是什么？我很困惑......）