How to access an object's parent object in Java?

Question

Have a look at this example:

class Parent{
    Child child = new Child();
    Random r = new Random();
}

class Child{

    public Child(){
        //access a me         


        

Answer 1

First of all your example doesn't demonstrate parent child relationship in java.

Its only a class using another type reference.
in this particular case you can only do new Parent().r //depending upon r's visibility.

or you can pass the Parent reference to Child (by changing Child's constructor).

class Parent{
    Child child = new Child(this);
    Random r = new Random();
}

class Child {
    public Child(Parent p){
        //access a method from Random r from here without creating a new Random()
        p.r.nextBoolean();
    }
}

In actual inheritance you don't need to do anything, the super class's members are inherited by extending classes. (again available in child class based on their visibility)

class Parent{
    Child child = new Child();
    Random r = new Random();
}

class Child extends Parent{

    public Child(){
        //access a method from Random r from here without creating a new Random()
        super.r.nextBoolean();
        //or even r.nextBoolean will be same in this case
    }
}

more at : http://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html