Question

Maybe I am just blind, but I do not see how to use Guice (just starting with it) to replace the new call in this method:

public boolean myMethod(String anInputValue) {
    Processor proc = new ProcessorImpl(anInputValue);
    return proc.isEnabled();
}

For testing there might be a different implementation of the Processor, so I’d like to avoid the new call and in the course of that get rid of the dependency on the implementation.

If my class could just remember an instance of Processor I could inject it via the constructor, but as the Processors are designed to be immutable I need a new one every time.

How would I go about and achieve that with Guice (2.0) ?

Answer 1

There is some time since I used Guice now, but I remember something called “assisted injection”. It allows you to define a factory method where some parameters are supplied and some are injected. Instead of injecting the Processor you inject a processor factory, that has a factory method that takes the anInputValue parameter.

I point you to the javadoc of the FactoryProvider. I believe it should be usable for you.