class lookup in javac

Jochen Theodorou blackdrag at
Fri Aug 8 12:43:36 UTC 2014

sorry, looks like my last reply did go to you personally.. Anyway.. 
thanks for the help, I am starting to feel more at home in javac source 
code now.

I successfully used javac to compile a class that extends another class, 
which exists only programatically.

If I wanted to get all the trees of the currently to be compiled 
sources... or I should maybe say all compilation units... is there a way 
to do that?

And one question for the compile states... does the compiler try to 
complete the compilation for a compile unit first, or does the compiler 
let all compilation units progress through all states at the same time? 
Like "for all compileUnits do process" then "for all compileUnits do 
attr" and so on. I am aware that this is simplified, since they can't 
all be in sync like that all the time, but I am interested in the 
general approach here.

bye Jochen

Am 07.08.2014 19:52, schrieb Maurizio Cimadamore:
> Hi Jochen,
> I would say that the root of all magic lies in Resolve.loadClass - i.e.
> that method is called whenever a class needs to be resolved given its
> qualified name. This triggers a lookup using ClassFinder (which is a new
> addition in JDK 9 compiler - if you are using older codebase you might
> find analogous routines under ClassReader). ClassFinder is responsible
> for resolving a qualified name into:
> *) a source file (i.e. if the file being compiled references another
> file that is part of same compilation)
> *) a class file (i.e. if the file being compiled references a class in
> the classpath)
> *) both a class and a source file (if both the above case apply)
> In the last case, ClassFinder will decide as to whether the source or
> the class file should be used by preferring the 'freshest' file (see
> ClassFinder.includeClassFile).
> After ClassFinder has established where the bits should be coming from,
> javac will create a new ClassSymbol corresponding to the 'shell' of the
> newly found class. Whenever javac needs to access to members of this
> class, it will use a completer to do so - initially this completer will
> point to ClassFinder.complete() itself, which will then route completion
> to either JavaCompiler (source completion) or ClassReader (classfile
> completion).
> I hope this helps.
> Maurizio
> On 07/08/14 13:50, Jochen Theodorou wrote:
>> Hi,
>> I am trying to understand javac internals a bit more and I am
>> currently trying to find out where exactly javac finds that it doesn't
>> know a class. I am also trying to identify where javac looks for a
>> precompiled class, and how that class is represented.
>> Can I get some pointers from you guys?
>> bye Jochen

Jochen "blackdrag" Theodorou - Groovy Project Tech Lead
german groovy discussion newsgroup: de.comp.lang.misc
For Groovy programming sources visit

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