Java reflection: How can I retrieve anonymous inner classes?

Question

I have an anonymous inner class inside another class (SomeClass).

Both SomeClass.class.getClasses() and SomeClass.class.getDeclaredClasses() return empty arrays.

I couldn't find some hints on this in Class' Javadocs.

Can anonymous inner classes be retrieved using reflection in some way?

What else are notable differences between anonymous inner classes and normal inner classes?

Related: stackoverflow.com/q/44475201/314291

StuartLC
– StuartLC

2017-06-10 16:43:47 +00:00
Commented Jun 10, 2017 at 16:43 — StuartLC
– StuartLC, Commented Jun 10, 2017 at 16:43

Peter Lawrey · Accepted Answer · 2009-10-31 16:57:54Z

4

You could try a brute force search of Class$1 ... Class$n until you can't find any more.

answered Oct 31, 2009 at 16:57

Peter Lawrey

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3 Comments

alphazero Over a year ago

Food for thought that given an anon inner class, you can find its enclosing Method, but getDeclaredInnerClasses() is not part of the Method api.

Stephen C Over a year ago

I think I can understand why there is no getDeclaredInnerClasses(). It would be impossible to implement without a change to the class file format.

Peter Lawrey Over a year ago

Classes support meta information, which where such information could go. I don't think it is there because a good use case may not have been found. Perhaps what you are trying to do could be done another way. e.g. with Enum's??

Tom Hawtin - tackline · Accepted Answer · 2009-10-31 17:27:50Z

0

If it's using reflection, it's probably a really bad idea. Leaving that aside, I believe you can additional inner classes at runtime, so it doesn't make sense to list classes that may not have been thought of yet. Listing currently loaded classes would, I guess, require going through Java agents or similar.

Anonymous inner classes have made up names, an enclosing method and additional synthetic fields for copying external local variables that have been copied. One class is pretty much the same as another at runtime. Remember that 1.1 introduced inner classes, but class files have barely changed since 1.0.

answered Oct 31, 2009 at 17:27

Tom Hawtin - tackline

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1 Comment

java.is.for.desktop Over a year ago

Though not a solution answer, good arguments. Will mark as correct.

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