问题
Having the following code: log.info("parameters {} and {}", param1, param2) compiles and works well with SLF4J in Scala
However if I want to pass more arguments, I need to use Array:
log.info("parameters {} and {} and {}", Array(param1, param2,param3))
which simply substitutes first parameter with array.toString and leaves rest of parameters unbound.
The following code
log.info("parameters {} and {} and {}", Array(param1, param2,param3) : _*)
doesn't compile, because of:
error: overloaded method value info with alternatives:
(org.slf4j.Marker,java.lang.String)Unit <and>
(java.lang.String,java.lang.Throwable)Unit <and>
(java.lang.String,Array[java.lang.Object])Unit <and>
(java.lang.String,Any)Unit
cannot be applied to (java.lang.String, Any)
log.info("parameters {} and {} and {}", Array(param1, param2,param3) : _*)
What am I missing here?
回答1:
I guess it all depends on the inferred type. The log.info method that takes an array is expecting an Array[AnyRef]. So as an alternative to the cast you could do
log.info("parameters {} and {} and {}", Array[AnyRef](1, 2, "a"): _*)
But this won't work as there's a restriction on implicit conversions between Int -> AnyRef. For those, you'll need a type ascription:
log.info("parameters {} and {} and {}",
Array[AnyRef](1: Integer, 2: Integer, "a"): _*)
See this question for more details: Result type of an implicit conversion must be more specific than AnyRef
回答2:
You should use a scala wrapper for slf4j like grizzled
If you're not bound to slf4j, you should check out Logula. I've been playing with that recently and I like it.
回答3:
what if you use string interpolation? like so:
log.info(f"parameters ${param1} and ${param2} and ${param3}")
回答4:
Try this:
Array(...).asInstanceOf[Array[Object]]
回答5:
Here is how I do it.
LOGGER.info("encode: {}, code: {}, length: {}", Array(messageWrapper, methodCode, bytes.length).asInstanceOf[Array[AnyRef]])
Cheers
来源：https://stackoverflow.com/questions/11940614/scala-and-slf4j-pass-multiple-parameters