Question

Suppose I have code like :

log.info("Now the amount" + amount + " seems a bit high")

and I would replace the log method with a dummy implementation like :

class Logger {
   ...
   public void info() {}

}

Will the optimizer inline it and will the dead code removal remove the parameter construction if no side effects are detected?

Answer 1

I would guess that the compiler (javac) will not, but that the just in time compiler very likely will.

For it to work however, it has to be able to deduct that whatever instructions you use to generate the parameter have no side effects. It should be able to do that for the special case of strings, but it might not for other methods.

To be sure, make a small benchmark that compares this with the code that Jesper suggested and see, whichever is faster or if they are equally fast.

Also see here: http://www.ibm.com/developerworks/java/library/j-jtp12214/index.html#3.0