calling a function in a class's “owner” class

Question

Following pseudocode sums up my question pretty well I think...

class Owner {
    Bar b = new Bar();

    dostuff(){...}
}    

class Bar {
    Bar() {
              


        

Answer 1

There are 3 possibilities :

1) making dostuff() static and call it like

Owner.dostuff()

2) Creating an instance of Owner inside the class Bar

class Bar {
   Owner o;
   public Owner() {
     o = new Owner();
     o.dostuff();
   }
}

3) Inject an Owner instance through the constructor

class Bar {
   public Owner(Owner o) {
     o.dostuff();
   }
}

Answer 2

This would work:

class Owner {

    Bar b = new Bar(this);

    dostuff(){...}
}    

class Bar {
    Bar(Owner myOwner) {
        myOwner.dostuff();
    }
}

Answer 3

If dostuff is a regular method you need to pass Bar an instance.

class Owner {

   Bar b = new Bar(this);

   dostuff(){...}
}    

class Bar {
   Bar(Owner owner) {
      owner.dostuff();
   }
}

Note that there may be many owners to Bar and not any realistic way to find out who they are.

Edit: You might be looking for an Inner class: Sample and comments.

class Owner {

   InnerBar b = new InnerBar();

   void dostuff(){...}

   void doStuffToInnerBar(){
       b.doInnerBarStuf();
   }

   // InnerBar is like a member in Owner.
   class InnerBar { // not containing a method dostuff.
      InnerBar() { 
      // The creating owner object is very much like a 
      // an owner, or a wrapper around this object.
      }
      void doInnerBarStuff(){
         dostuff(); // method in Owner
      }
   }
}

Answer 4

In the way you're putting it, there is no way of calling the "owner" in Java.

Object A has a reference of object B doesn't mean that object B even knows that object A exists.

The only way to achieve this would be either though inheritance (like you said yourself), or by passing an instance of object Owner to the constructor of Bar.

Answer 5

class Owner {
    Bar b = null;
    Owner(){
       b = new Bar(this);
    }
    dostuff(){...}
}    

class Bar {
    Owner o = null;
    Bar(Owner o) {
        this.o = o;
    }
}

Now, instance b of Bar has a reference to o of type Owner and can do o.doStuff() whenever needed.

Answer 6

I think you are looking for nested Clases Nested Classes Sun

This way u can write outer.this.doStuff();

Have a look to that topic: Inner class call outer class method