I've discovered a strange behavior for mutable sets which I cannot understand:
I have a object which I want to add to a set. The equals method for the class is overridden. When I add two different objects to the set, which produces the same output for equals method, I get a different behavior between mutable and immutable sets for the contains method.
Here is the code snippet:
class Test(text:String){
override def equals(obj:Any) = obj match {
case t: Test => if (t.text == this.text) true else false
case _ => false
}
override def toString = text
}
val mutableSet:scala.collection.mutable.Set[Test] = scala.collection.mutable.Set.empty
mutableSet += new Test("test")
println(mutableSet)
println(mutableSet.contains(new Test("test")))
val immutableSet:scala.collection.immutable.Set[Test] = scala.collection.immutable.Set.empty
immutableSet += new Test("test")
println(immutableSet)
println(immutableSet.contains(new Test("test")))
This produces as output:
Set(test)
false
Set(test)
true
In my opinion both calls of contains should produce the same output (true).
Could anybody help me to understand the difference here or is this a bug in the scala immutable set implementation? By the way, I use scala 2.8.1.final
Thanks.