Where next for Java?

Question

What are Sun's plans for future changes to the Java language and API? I can think of a few cool things that Sun could go for:
* Tuples, a la Python, Prolog, and others.
* Multi-dimensional arrays (jagged arrays suck, am I right?)
* Better support for the Collections API in Swing.
* A first-class calendar component for swing, like JCalendar or the MFC calendar.
* Currying! Just kidding.
* Operators for BigDecimal and BigInteger, and java.lang.Math support for them too.
* Some sort of a SortedList collection, for lists that have to stay sorted.
That's just my little want-list for Java 1.6. I'd regard any one of these as a HUGE enhancement to Java. Thanks for reading!

Answer 1

A mixin is like a data member whose methods get exposed as part of the owning object. The idea is that if your class needs to implement some interface, you can use an object that already implements that interface to do it.
Suppose I have a class Foo that needs to implement interface Heuvos:
class Foo implements Heuvos {
}Rather than implement the methods of Heuvos directly, Foo uses another object -- the mixin -- to implement that functionality.
class Foo implements Heuvos {
    mixin Heuvos h;
    public Foo(Heuvos input) {
        h = input;
}See? The object gets mixed into our class, and handles the implementation of the Heuvos interface. It's like multiple inheritance, but without the potential problems with constructors and cyclic inheritance. Plus, you can decide at runtime what object will provide the implementation -- this makes the technique extraordinarily flexible.
Personally, I think Mixins would be a great addition to Java. It would be a non-trivial addition to the language, but boy is it ever a powerful one!