What is missing in the current and planned standard Java class library?

Question

When looking through the JDK, I often think to myself, "Why isn't this included in the JDK?"

I know there's Apache Commons and various other libraries, but there are somethings that are just so fundamental that I feel it should be added to the JDK.

What are some things missing that you think should be added to the JDK?

Answer 1

I'll answer my own question to get this rolling.

One thing that is used everywhere in Swing is Listeners. Why isn't there a standard set of classes that implement the Model and Listener? Part of the problem here is Swing (where listeners are used most) came before generics. Thus Listeners are implemented without generics, hence the unreusability of the current implementation. We would reduce so much code duplication with a standard Model/Listener implementation.

Answer 2

What is also missing is a caching system.

It would be nice if the JDK included a cache system works both as a in memory cache and on disk cache.

Unfortunately, they would use the poor Serialization engine they have right now.

Answer 3

Closures. Its not a library, but a more inherit java language artifact. Still, if there is a single thing in Java that I miss is Closures.