problem when using with a library that uses java-8

[ligi]

A library I am using is switching to java-8 - so I thought I use retro-lambda to work around this. Unfortunately it does not seem to work.

* What went wrong:
Execution failed for task ':app:preDexDebug'.
> com.android.ide.common.internal.LoggedErrorException: Failed to run command:
    /home/ligi/bin/android-sdk/build-tools/21.1.2/dx --dex --output /home/ligi/git/EtherDroid/app/build/intermediates/pre-dexed/debug/ethereumj-core-0.7.15-SNAPSHOT-e51b5aa0b29943dc2aab8890d25951d99dcee695.jar /home/ligi/.m2/repository/org/ethereum/ethereumj-core/0.7.15-SNAPSHOT/ethereumj-core-0.7.15-SNAPSHOT.jar
  Error Code:
    1
  Output:

    UNEXPECTED TOP-LEVEL EXCEPTION:
    com.android.dx.cf.iface.ParseException: bad class file magic (cafebabe) or version (0034.0000)
        at com.android.dx.cf.direct.DirectClassFile.parse0(DirectClassFile.java:472)
        at com.android.dx.cf.direct.DirectClassFile.parse(DirectClassFile.java:406)
        at com.android.dx.cf.direct.DirectClassFile.parseToInterfacesIfNecessary(DirectClassFile.java:388)
        at com.android.dx.cf.direct.DirectClassFile.getMagic(DirectClassFile.java:251)
        at com.android.dx.command.dexer.Main.processClass(Main.java:704)
        at com.android.dx.command.dexer.Main.processFileBytes(Main.java:673)
        at com.android.dx.command.dexer.Main.access$300(Main.java:83)
        at com.android.dx.command.dexer.Main$1.processFileBytes(Main.java:602)
        at com.android.dx.cf.direct.ClassPathOpener.processArchive(ClassPathOpener.java:284)
        at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:166)
        at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:144)
        at com.android.dx.command.dexer.Main.processOne(Main.java:632)
        at com.android.dx.command.dexer.Main.processAllFiles(Main.java:510)
        at com.android.dx.command.dexer.Main.runMonoDex(Main.java:280)
        at com.android.dx.command.dexer.Main.run(Main.java:246)
        at com.android.dx.command.dexer.Main.main(Main.java:215)
        at com.android.dx.command.Main.main(Main.java:106)
    ...while parsing org/ethereum/Start.class

    1 error; aborting


* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

A bit more background here: https://github.com/ethereum/ethereumj/issues/184

I have the feeling that retro-lambda only works for classes that are in the project - not for ones coming from libraries. Is this correct? If so - is it possible to also work for the libraries used?

[evant]

That is correct, it only works for your source code, all libraries must be java 6/7. In theory it could process libraries by scanning for java 8 jars, unpacking them, running them through retrolambda, packing them back up, then depending on the processed jar instead. However, none of this is implemented and would take a bit of work.

[ligi]

thanks for the fast information and your work in general!

[Noisyfox]

Did the new plugin with transform api solve this problem? Will the transform be applied to the external jar files' .class files?