Hi Peter,
On 04.04.2016 11:39, Peter Levart wrote:
Hi Georgiy,
On 04/01/2016 04:52 PM, Georgiy Rakov wrote:
Hello,
currently inner classes are allowed to be specified in 'uses'
statement, for instance following code is compiled successfully by
JDKb111 javac:
a/module-info.java:
module a {
uses pkg.Outer.Inner;
}
a/pkg/Outer.java:
package pkg;
public class Outer{ public class Inner{} }
Spec doesn't prevent it either. However in 1.1.3
<http://cr.openjdk.java.net/%7Emr/jigsaw/spec/lang-vm.html> it
prevents implementations specified in 'provides' statement to be
inner classes. According to my understanding inner class cannot be
extended by non-inner class, for instance "public class Impl extends
Outer.Inner { } " would cause:
error: an enclosing instance
that contains Outer.Inner is required
class Implem extends Outer.Inner {}
^
1 error
So could you please tell what is the purpose of allowing inner
classes to be specified in 'uses' statement, there seem to be no way
to create its implementation. Should it be prohibited by spec?
The minimized testcase is attached; in order to run it please:
1. unzip attached archive on Windows machine;
2. rename test12\test_bat to test12\test.bat;
3. modify test.bat by changing JDK_HOME variable to point to your JDK
installation;
4. run test.bat.
Thank you,
Georgiy.
Not only in 'uses' statement. It would be impossible to specify them
in 'provides ... with ...' statement as implementation classes too as
they by definition can't be instantiated without an outer instance
(their constructors always contain an implicit parameter - the outer
instance). What does compiler say for such case?
a/module-info.java:
module a {
exports pkg;
provides pkg.Service with pkg.impl.Outer.Inner;
}
a/pkg/Service.java:
package pkg;
public interface Service {}
a/pkg/impl/Outer.java:
package pkg.impl;
public class Outer { public class Inner implements pkg.Service { } }
For such case jdk9b113 javac says:
a\module-info.java:3: error: the service implementation is an inner
class: Outer.Inner
provides pkg.Service with pkg.impl.Outer.Inner;
^
1 error
As I've already said this is according to spec:
It is a compile-time error if the service implementation named by
the |with|clause of a |provides|statement is |abstract|, or is not
|public|, or does not have a |public|no-args constructor, or is *an
inner class* (JLS 8.1.3).
But spec doesn't prevent service interfaces to be inner classes.
Thanks,
Georgiy.
Regards, Peter
