Hi,
I'm trying to figure the intended process for compiling different
versions of a class for a multi-release (MR) JAR if there is a module
descriptor present.
I have these classes:
--- src/main/java/com/example/Version.java
package com.example;
public class Version {
private String value; String getValue() { return value; }
public Version(String value) { this.value = value; }
}
---
--- src/main/java/com/example/A.java
package com.example;
public class A {
public Version getVersion() { return new Version( "Java 8" ); }
}
---
--- src/main/java9/com/example/A.java
package com.example;
public class A {
public Version getVersion() { return new Version( "Java 9" ); }
}
---
I.e. "Version" is common to all Java versions supported by the MR JAR,
whereas there is one variant of "A" for Java 8 and one for Java 9.
If I don't have a module descriptor things work fine:
javac --source-path=src/main/java -d target/classes --release 8
$(find src/main/java -name "*.java")
javac --source-path=src/main/java9 -cp target/classes -d
target/classes-java9 --release 9 $(find src/main/java9 -name "*.java")
jar --create --file mr.jar -C target/classes . --release 9 -C
target/classes-java9 .
Specifically, the second javac call picks up the (shared) class file
for "Version" from the classpath by pointing to the output directory
of the first compilation.
Things fail when adding a module descriptor:
--- src/main/java9/module-info.java
module com.example {
}
---
Now the second javac call fails:
src/main/java9/com/example/A.java:4: error: cannot find symbol
public Version getVersion() { return new Version( "Java 9" ); }
^
symbol: class Version
location: class A
It seems as if the presence of module-info.java suppresses the
configured classpath. Reading JEP 261 [1] I assumed this should be
supported: "It is possible to put arbitrary classes and JAR files on
the class path in [Single-module mode]", which I think is what I have
here.
Am I running into a bug? Or am I on the wrong track here and creating
such MR JAR should be done differently? If so, how should classes that
are meant to go into META-INF/versions/9 be compiled without
re-compiling all the shared classes?
Thanks for any pointers,
--Gunnar
[1] http://openjdk.java.net/jeps/261
