The Java type system is broken

#1

Post by tdurden » Thu, Jul 19, 2018, 12:43 PM UTC

The Java type system is broken
wouter.coekaerts.be

Re: The Java type system is broken

#2

Post by Froyoh » Thu, Jul 19, 2018, 1:38 PM UTC

Not broken. Working as intended.

Re: The Java type system is broken

#3

Post by lmm » Thu, Jul 19, 2018, 1:40 PM UTC

Froyoh wrote: post #2

Not broken. Working as intended.

Nonsense. There are four bug reports at the bottom of the article; all seem to have been accepted as bugs and one has already been fixed.

Re: The Java type system is broken

#4

Post by viach » Thu, Jul 19, 2018, 1:44 PM UTC

From the examples: "String s = gridWrapper.get(0).get(0).get(0);" - Java type system is broken!

Java is not perfect, but this looks to me like a broken code indeed ".get(0).get(0).get(0)".

Could we rephrase the message of the article as "If you write really broken code in Java, you might be not guarded by the type system". And this is, well, uhm, well... acceptable?

Re: The Java type system is broken

#5

Post by TazeTSchnitzel » Thu, Jul 19, 2018, 1:45 PM UTC

My favourite feature of Java's type system is that, because any object type also accepts null, the type system is unsound and you can convert anything to anything else:

https://raw.githubusercontent.com/namin/unsound/master/doc/u...

Re: The Java type system is broken

#6

Post by wintorez » Thu, Jul 19, 2018, 1:47 PM UTC

* The Java is broken

Re: The Java type system is broken

#7

Post by rimunroe » Thu, Jul 19, 2018, 1:47 PM UTC

viach wrote: post #4

From the examples: "String s = gridWrapper.get(0).get(0).get(0);" - Java type system is broken! Java is not perfect, but this looks to me like a broken code indeed ".get(0).get(0).get(0)". Could we rephrase the message of the article as "If you write really broken code in Java, you might be not guarded by the type system". And this is, well, uhm, well... acceptable?

Is a type system really worth that much if it can't help you in a situation where your code is ugly and hard to follow?

Re: The Java type system is broken

#8

Post by npstr » Thu, Jul 19, 2018, 1:48 PM UTC

Java generics are broken? What else is new?

Re: The Java type system is broken

#9

Post by stingraycharles » Thu, Jul 19, 2018, 1:48 PM UTC

TazeTSchnitzel wrote: post #5

My favourite feature of Java's type system is that, because any object type also accepts null, the type system is unsound and you can convert anything to anything else: https://raw.githubusercontent.com/namin/unsound/master/doc/u...

Wouldn't that be a problem in most languages? Even Haskell allows for it through Data.Dynamic

If I can serialize to String, and then deserialize a String to any type of class, I can effectively "cast" anything to anything.

Re: The Java type system is broken

#10

Post by buremba » Thu, Jul 19, 2018, 1:49 PM UTC

Welcome to the world of enterprise-ready complex applications. I agree that these cases should be covered by the compiler but man, there are mainstream languages that don't implement generics just because they're complex and pretend that they're not helpful.

It would be nice of you to compare Java generics with equivalents instead of just criticizing it. It doesn't help anyone writing "this is broken" not offering any alternatives or suggesting ways to fix the problem.