Unclear whether Erjang can interface with Java code, e.g. Android UI

[mcandre]

Can Erjang call Java code?

Can Erjang be used to write Android apps?

[krestenkrab]

Yes, Erjang can call Java code; syntax like:

foo() ->
    'java.lang.System':'gc'();

lets you call static Java methods. Returned objects can pose as Erlang terms. E.g. if it implements java.util.List, then it can pose as an Erlang list (i.e. you can match/deconstruct it). See more here: http://www.javalimit.com/2010/06/a-java-api-for-erjang.html

Currently, you cannot use Erjang to write Android apps; but it might not be totally undoable. Erjang has a byte code interpreter (use command line +i) which disables the to-JVM-bytecode-JIT, and this should in principle allow us to run apps on Android; but it has never been tried and there are probably a handful of classes that are being dynamically generated that could have been statically generated. Problem with Android is that dynamic code generation (JVM code) cannot be depended upon.