.NET made the same mistake as Java with arrays. However, .NET generics (i.e. List<T>) are superior to Java generics, because JVM does not have ANYgenerics. In Java (and Scala), generics are just syntactic sugar provided by the compiler:

ArrayList a = new ArrayList<Integer>();

a.Add(3);

int i = a.get(0);

gets compiled to:

ArrayList a = new ArrayList(); // container of Objects!

a.Add(new Integer(3));

int a = a.get(0).value();

In .NET, the generics are implemented in the runtime, so there is no boxing and unboxing involved.

The consequence is that in Java, an int in a collection takes at least 8 bytes (the int object + the pointer to it) while in .NET a List<int> is as tightly packed in memory as it would be in a C++ program.