Hejlsberg Talk About Generics in C# and Java

An anonymous reader writes "artima.com has a very interesting interview with Anders Hejlsberg - the Borland guy now at Microsoft who can best be defined as MR C# - doing all the stuff that Borland wouldn't let him do. He discusses generics in C#, Java (1.5) and C++. Naturally there is the chance of bias but he does raise some interesting points againt Java's generics. Specifically that Java's genericised collections will have to box all primitive types as full objects, whereas C# does not. This is a big performance plus for C#. Java created the primitive types in the first place to address performance concerns but appears to be stepping sideways here. I can't help wondering if Sun has taken this approach to get the syntatic sugar in the language without requiring a bytecode change, but perhaps in a future VM version will allow primitive generics (obvioulsy forcing a bytecode regeneration)?"

Comments

Nothing's changed here...

[Dr. Bent]

Specifically that Java's genericised collections will have to box all primitive types as full objects, whereas C# does not. This is a big performance plus for C#.

The Java collections operate this way right now (in JDK 1.4) and AFAIK have operated this way since the beginning. You can't add a primitive type to a collection, genericised or not, it has to be a first class Object. In terms of performance, whether or not the conversion is done explicitly or automatically shouldn't matter. If anything, the automatic conversion with autoboxing should be faster because it can be optimized "under the covers" in the compiler or the JVM.

I don't see how this performance issue is related to generics in C# vs Java.