Thanks a lot, Jon,
This is very helpful.
As you mention legacy mode as "no modules being compiled", this mode
is still tied to the -source, -target, and --release options, right?
IOW, the fact that the command line without module-info.java succeeds
is not owed to using a different compilation mode, but to compiling
everything in the same unnamed module, right?
Does JEP 261 have a process for correcting the text after it has been delivered?
Which space should I watch for updates?
- http://openjdk.java.net/jeps/261
- https://bugs.openjdk.java.net/browse/JDK-8061972
- any other?
regards,
Stephan
On 07.11.2017 23:03, Jonathan Gibbons wrote:
On 11/07/2017 12:56 PM, Stephan Herrmann wrote:
On 07.11.2017 21:43, Alan Bateman wrote:
On 07/11/2017 18:56, Stephan Herrmann wrote:
I recently noticed that compilers start to ignore -classpath as soon
as module-info (.java or .class) is found during the compile.
(Incidentally, javac and Eclipse compiler agree in this).
Using a trivial test class this works:
$ javac -classpath junit4.jar -d bin/ src/pkg/TestJUnit4.java
This doesn't (cannot resolve any types from junit4.jar):
$ javac -classpath junit4.jar -d bin/ src/pkg/TestJUnit4.java
src/module-info.java
The module you are compiling doesn't read the unnamed module. You can't write
"requires $CLASSPATH" for example.
If you add `--add-reads <module>=ALL-UNNAMED` to the command line then it
should compile.
-Alan
Thanks, Alan, that would work.
But that is not what I meant when referring to JEP 261.
In JEP 261 I see (under "Single-module mode"):
"It is possible to put arbitrary classes and JAR files on the class path in
this mode,
but that is not recommended since it amounts to treating those classes and JAR
files as
part of the module being compiled."
Doesn't this say, my above command line treats junit4.jar as part of the
current module,
*not* as an unnamed module?
Is everything referenced via -classpath definitely treated as an unnamed module?
Independent of single-/multi-module modes?
Stephan
Stephan,
I think you have identified some outdated text that needs to be fixed.
The text was correct at one point, when the distinction between "single module
mode"
and "multi-module mode" was a bigger deal.
These days, the primary distinction is between "classpath (legacy) mode" (no
modules being compiled)
and "module mode" (one or more modules being compiled.)
Here's how javac treats these modes:
In classpath (legacy) mode ...
* the sourcepath, classpath and output directory behave as previously, such as
in JDK 8.
In module mode ...
* all classes on the classpath (-classpath) are treated as part of the unnamed
module.
* if you are just compiling a single module, you may either put the source for
that module
on the source path (-sourcepath) or in a directory on the module source path
(--module-source-path).
* if you are compiling multiple modules, they must be in separate directories
on the
module source path (--module-source-path).
* javac will implicitly look for previously compiled classes in the output
directory (-d).
(This is in contrast to the usage in classpath/legacy mode, where it has always
been common practice
to explicitly put the output directory on the classpath as well.)
-- Jon
