Type of Class

Joe Darcy joe.darcy at oracle.com
Fri Feb 21 17:59:35 UTC 2014

On 02/21/2014 07:40 AM, Brian Goetz wrote:
> I understand why you want this, though I think you’ll find that there are still thousands of other things “missing” from reflection.
> In the Java 1.0 days, the difference between the Java language and the class file was pretty small.  So reflection served as both the class file (VM) reflection and language reflection mechanism.  But, over time, the gap has grown wider.  We’ve made the decision (though not always consistently applied) that reflection is about serving up the class file information to Java, not about answering questions about the Java language.  So, for example, it can’t tell that one method is a bridge for another, or easily answer questions about inheritance or overriding.  Similarly, the issues raised here are about gaps between the class file representation of a class and the language level model.
> Historically we have added some things to reflection to fill in these gaps.  However, our current strategy is to expose this through javax.lang.model, which is designed to reflect the langauge-level view of the world, and this is what users really want anyway.  Currently the only implementation of javax.lang.model that is available is in the compiler, exposed to annotation processors, but we have a plan to expose one backed by core reflection which is a more sensible way to express the information you are looking for.

The nested class situation is so tricky, I wrote a blog entry about it 
complete with a diagram:


The javax.lang.model API uses a NESTING_KIND enum to model these 


As of JDK 8, we've published a proof of concept implementation of 
javax.lang.model backed by core reflection as sample code:




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