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Comment by ardit33 | Hacker News Reader

for very beginners, yes... Java is not the right programing language to teach. (I'd say Python is).

But for intermediate/advanced classes I think Java is a must learn for every CS graduate.

1. While it is bloated, it has so many modern and not so modern concepts into it, that learning it makes you understand those concepts better. (eg: It is hard to understand Generics if your favorite language doesn't have them)

2. A lot of enterprises (and major tech) backends still run on Java. I thin knowing it is a must to be competitive in the job market as a fresh grad

3. Learning Java (and probably disliking it) it will make you appreciate and perhaps make you better at learning other more nimble languages (aka. GoLang and friends)

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Weird reason to promote something in CS courses.

CS programs aren't to let you make some easy money in the next few years. CS programs are to provide an thorough and high level of computing, from which writing code is just a small part. Having a CS degree much more than learning a language and framework.

If one's goal is just to earn some money in the next few years, he would be better served by taking an Udemy course.

University didn't teach me how to code, I did that myself before going to university. What it did teach was the why's and how's of computing without which I would be just a code monkey churning code without having a better understanding.

It is the same difference between someone who make an course learning how to repair electrical appliances and electronics and the engineer who designs them.

I don't particularly agree with the first two but I can WHOLLY agree on the third, in fact, I think I blame Java for my infatuation with FP

I'd like to stress on the second point. When I graduated at 2015, and have done multiple interviews with enterprises, Java or .NET were critical. Don't know if it's the same, but looking into job postings, I'd say it is.

It'd definitely different if you work for an IT company, but not always.

It’s kind of embarrassing but I didn’t understand generics from my beginner CS course (taught in Java). It wasn’t actively tested on either. I only began to appreciate it when I took an online MOOC in OCaml on a whim.

Generics in Java were poorly-handled and almost universally considered to be a mistake.

Say that to the Scala.NET folks.

Why is that? And how so?

I'm not the OP, but look up "type erasure" for one criticism.

Type erasure gets an unfairly bad rap. Yes, it makes reflection difficult sometimes. Yes, it doesn't play well with value types. But other than that, erasure is a very powerful concept.

My understanding is that the only value in type erasure is that it maintains compatibility with libraries compiled in ancient versions of Java. Are there language-level benefits to type erasure?

Absolutely. Erasure lets you write code that's actually generic, instead of code that appears to be generic.

For example, in C# IList<Foo> and IList<Bar> are two different interfaces that happen to have similar methods. Whereas in Java, List<Foo> and List<Bar> are the same interface. This means you can do things like this in Java:

    List<?> list = ...
    Object o = list.get(0);

To do something similar in C# is significantly more effort. You either have to duplicate all of your interfaces (IList + IList<T>), use `dynamic`, or use reflection to compile delegates at runtime.

A common complaint is "but erasure lets you add an integer to a list of strings". But as long as you follow PECS[1] rules you can avoid most of those situations.

[1] Producer: extends. Consumer: super

I don't think either of your points has anything to do with type erasure, and everything to do with allowing generics to take value types. This was an easy decision in Java, since it doesn't (yet?) allow user-defined value types. But C# has had `struct` since the beginning.

C# creates one instance of a generic for all reference types. The general consideration in instantiating multiple versions is object size. All reference types are the same size, so not a concern. Value types, however, range wildly in size and so generally get their own specialized versions during code generation.

The same choice effects the ability to wildcard. C# probably could implement wildcards over reference types, but it would feel inconsistent without value types. And, honestly, a good portion of wildcarding in my experience is to handwave away the compiler when you know what you're doing without reified types. Simply not an issue in C# -- its stronger guarantees around generic types means I can make that same code generic over the type I'm wildcarding in Java.

Code generation is definitely important to talk about, but that really wasn't the focus of my first example. Even if Foo and Bar were both reference types, the same reasoning would apply.

In C#, you can do:

    class MyClass : IList<Foo>, IList<Bar> { ... }

In Java, you can't do:

    class MyClass implements List<Foo>, List<Bar> { ... }

I know this is commonly viewed as an annoying restriction, but, IMO, it's rather an indication that you're writing code that doesn't respect the contract of the generic interface. For example, what should the `Count` property return if you're implementing IList<T> twice? (C# wiggles around this with explicit interface implementations, but I think it's fair to argue that that's not a strictly superior approach to Java's).

Yes, Scala could not map their generics concepts to .NET due to reified generics and their developers gave up on Scala.NET.

I really want to know what other languages large enterprises are using that have, or are on the track to getting, the kind of volume Java has. Especially languages that don't run on the JVM.

Go and nimble? Jesus christ, you can't be serious.

Python is perfect for learning programming logic.

Wouldn't have wanted it any other way.

Nope, it's only slightly better than java. Lisps and MLs are objectively better when it comes to teaching Cs materials.

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