Question

So this may be a very simple question that I’m overthinking but if I do something like the following:

class A{
    public String test_string = "before (default)";
    public A(){
        B b = new B(this);
    }
    public void testA(){
        this.test_string = "after (new)";
    }
}

where B is:

class B{
    private A parent;
    public B(A mParent){
        parent = mParent;
    }
    private void testB(){
        System.out.println(parent.test_string);
    }
}

Would that allow me to still access the same instance of A (all of its public fields and methods)? If I called A.testA() from another class somewhere else on that specific instance of A, would the B that was constructed in that A‘s constructor’s testB function return the "after (new)" string? Or would that be a copy of A because doesn’t java assign by value, not reference? Is there a better way of doing this? Am I just over complicating the issue?

I wasn’t sure what to search for so I couldn’t find other questions that answered my question.

Thanks in advance!

Answer 1

Yes, it is the same instance. It works like shown in this image:

So, calling a method over b.parent.foo, it is called over the same instance passed in the constructor.