When overriding equals in Java, why does it not work to use a parameter other than Object?

Question

I ran into an interesting behavior recently. It seems that if I override .equals() to take a parameter other than Object, it doesn\'t get called. Can anyone explain to me

Answer 1

You're assuming that the contains() method in List knows the type of the object at runtime, which is incorrect.

Because of erasure, List becomes just a regular List at runtime, so the contains() method sees its parameter as an Object, thus invoking Object's equals() instead of the one you defined for MyClass in its execution.