Compiling D2RQ with ant

Question

D2RQ is shipped with an ant build script, which works fine. I can compile on a linux box, where the default ant version is 1.8.2 and the javac version is 1.7.0_121.

I want to compile D2RQ with Java 8. I've downloaded ant 1.10, which requires Java 8 ².

Then I run into some issues:

• When I run ant 1.10 without changing the source (or target) option, ant seems to run successfully - even though the default version of java on the system is 1.7 (i.e. <8) - I would have expected it to complain it didn't have a valid version of java?

• I've tried modifying the compile target in the build.xml file from

  source="1.5"
  target="1.5"
  

  to

  source="1.8"
  target="1.8"
  

  but I get an error of:

  compile:
      [javac] Compiling 171 source files to /home/chris/d2rq/bldsrc
      [javac] javac: invalid target release: 1.8
  

  I get the same error if I replace '1.8' with just '8', but '1.6' and '1.7' both work.

• I then tried a different approach (after a bit more Googling) and replaced

  source="1.5"
  target="1.5"
  

  with

  fork="yes"
  executable="/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.111-0.b15.el6_8.x86_64/jre/bin/java"
  

  the location of java 8 is valid, but running the compile task now results in

  compile:
      [javac] Compiling 171 source files to /home/chris/d2rq/bldsrc
      [javac] Unrecognized option: -d
      [javac] Error: Could not create the Java Virtual Machine.
      [javac] Error: A fatal exception has occurred. Program will exit.
  

I don't even know if -d is a D2RQ compile option or a valid java flag.

Is there anything else I should be trying?!

Answer 1

The executable attribute of <javac> must point to the javac executable, not java. Note the "c" at the end of javac.

The following must be changed to point to javac:

executable="/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.111-0.b15.el6_8.x86_64/jre/bin/java"

Where javac lives depends on your Linux distribution.

Answer 2

There is also ONT-D2RQ with java8, jena3 and maven