Get all instances created by Guice Provider

Question

Assuming a ClassX as:

class ClassX {
    
    int value;
    
    ClassX() {
        this.value = new Random().nextInt(10);
    }

    //equals and hashCode depend on "value"
}

If I have a Provider as:

@Provides
public ClassX createInstance() {
    return new ClassX();
}

Is there a way to inject all the instances created, so I can sum up all values in total? I tried something like:

@Inject
public Test(Set<ClassX> set) {
    this.set = set
}

int total() {
    return this.set.stream()
            .map(classX -> classX.value)
            .reduce(0, Integer::sum);
}

but it fails. Worth mentioning that I read about MultiBinder but I would need the instances in order to add them to the Set, so, does not seem an option for this case.

Answer 1

Would the simple case of just maintaining the list inside of the Provider do the trick? Work in your preferred method of thread safety around instances.

class MyProvider implements Provider {
   Set<ClassX> instances = new HashSet<>();

   public ClassX get() {
        ClassX classX = new ClassX();
        instances.add(classX);
        return classX;
   }

   public Set<ClassX> getInstances() {
      // ... calculate what you need
   }
}

I don't believe there is any way to tell Guice to save all of the instances it's created or provided.