Question

Can someone clarify the significance of the below code.

class A
{
    int i = 10;

    public void setI(int b)
    {
        i = b;
    }

    public int getI()
    {
        return i;
    }
}

class Test
{    
    public static void main(String args[]) throws Throwable
    { 
        final A ob = new A();
        ob.setI(10);
        System.out.println(ob.getI());
    }
}

The object A is declared as final, but I can change value of this object’s instance variable and also retrive the updated value. So what are the significance of declaring an object as final.
I am aware about declaring primitive datatype as final, which makes that variable constant.

Answer 1

ob will not be able to reference any other object : final keyword.

It can not be reassigned. But you can change its internals (it is mutable, if it was originally).
So this works :

  final A ob = new A();
  ob.setI(6)

but this doesn’t :

  final A ob = new A();
  ob = new A();