Guice how to bind one class with different paramaters?

Question

I want to create two instances with one class by injecting different parameter. For example:

class Foo {
  private String config;
}

I want two Foo instances, one's config is A, another one is B, how should I do?

Answer 1

There are lots of different ways to achieve what you are after. without a little more information of your use case its hard to say the better of the ways.

For this answer i'll limit the scope to provide you with an example of a provider type solution.

first fully defined your class

    private class Foo {
    private String config;

    public Foo(final String config)
    {
        this.config = config;
    }
}

In your GuiceModule.java create 2 different providers

@Provides
@Named("foo1")
public Foo provideFoo1() {
    return new Foo("value1");
}

@Provides
@Named("foo2")
public Foo provideFoo2() {
    return new Foo("value2");
}

and then these objects can be injected into a single object (like below) or multiple different objects

private class ManagerManager {
@Inject
public ManagerManager(
        @Named("foo1") final Foo config,
        @Named("foo2") final Foo config2) {}
}

if injecting one of them into multiple objects, you may wish to have a singleton concept for both Foo1 and Foo2, so add @Singleton onto the provider

if you have a use case that the value (for foo1/foo2) is not known until runtime, then its better to ask for an example of an assistedFactory