Right, you can’t turn a mutable object into an immutable object when other references to the mutable interface already exists. Const as in C/C++ is certainly a

Right, you can’t turn a mutable object into an immutable object when other references to the mutable interface already exists. Const as in C/C++ is certainly a useful feature that Java lacks, but it’s quite a leap from that to claiming that Java doesn’t support true immutability. I develop Java applications with immutability as the default, and it works quite well. The lack of the abive-mentioned feature is not a critical obstacle. Regarding your point about collection views, const references are often also just views on mutable objects, and this poses no particular difficulty. And you can implement truly immutable collections in Java if you really insist on it.