Vertx 3 application logging from Javascript

Question

Sometimes it's nice to log things to the console during development. In a Vert.x 3 project I'm creating, I'm trying to follow the instructions on the docs page for Vert.x 3 for logging:

http://vert-x3.github.io/docs/vertx-core/js/#_logging_from_your_application

The docs provide this sample code:

// Note -these classes are Java only

// You would normally maintain one static instance of Logger per Java class:

var logger = Java.type("io.vertx.core.logging.LoggerFactory").getLogger(className);

logger.info("something happened");
logger.error("oops!", exception);

When compiling, the "var logger = ..." line bombs out with this error:

Failed in deploying verticle java.lang.RuntimeException: java.lang.ClassNotFoundException: io.vertx.core.logging.LoggerFactory at jdk.nashorn.internal.runtime.ScriptRuntime.apply(ScriptRuntime.java:391) at jdk.nashorn.internal.scripts.Script$Recompilation$13$1895AAAAA$\^eval_.L:27$_load(null:107) at jdk.nashorn.internal.scripts.Script$Recompilation$4$4036AAAA$\^eval_.L:27$doRequire(null:149) at jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:644) at jdk.nashorn.internal.runtime.ScriptFunction.invoke(ScriptFunction.java:229)

(Note: that "className" variable looks suspicious too. It doesn't say anywhere what that's supposed to be, it's "undefined" at compile time at the moment)

Any ideas?

Answer 1

This is due to versions getting slightly out of sync in the Vertx 3 milestones. The documentation already reflects a change upcoming in milestone 7 where the class package is:

    io.vertx.core.logging.LoggerFactory

However, in milestone 6 you need to use:

    io.vertx.core.logging.impl.LoggerFactory

If you update your code to:

    var logger = Java.type("io.vertx.core.logging.impl.LoggerFactory").getLogger(className);

it should work.