Overriding confusion - Please help!

[Sharda Vajjhala]

Consider this:

<font size=2.5>
Robot.java:
class Robot{
    int power = 5;
    public void printMe()
    {
       System.out.println("Yup, I'm a robot");
    }}
----------------------------------
Cyborg.java:
class Cyborg extends Robot{
    int power = 10;
    public void printMe()
    {
       System.out.println("Me, I'm a Cyborg");
   }}
-----------------------------------
TestCyborg.java:
class TestCyborg{
   public static void main(String args[]){
       Robot ry = new Cyborg();
       System.out.println(ry.power);     
       ry.printMe();
  }
}

Output is:
5
Me, I'm a Cyborg
If I am instantiating Cyborg, shouldn;t it print 10 instead of 5?
(edited by Cindy to format code)
[This message has been edited by Cindy Glass (edited November 13, 2001).]

[Fei Ng]

Instance Var dont get overriden.
so printout is int power = 5
But you can hide them in your subclass.
In your case you are using the
reference Robot so it will print out Robot's
int power.
But if you use the Cyborg's reference
Cyborg's int power will be printed.
And thats hiding Robot's int power in
Cyborg.


[This message has been edited by FEI NG (edited November 13, 2001).]

[Marium Hasan]

Hello,
The fact is that:
a) instance method is always called of which instance (i.e Cyborg )is created.
b) However, keep in mind that when an instance variable is used, it will always be of the type of class . here, in this case is Robot.
Since Robot rm = new Cyborg();
Hope it helps & check this for yourself by practising.
Regards,
Marium

[Colin Kenworthy]

Try this,
In your Robot and Cyborg classes add this method...
public int getPower() {
return this.power;
}
...then in class TestCyborg instead of printing ry.power, print ry.getPower()
System.out.println(ry.getPower())
I too expected to see 10, so thanks everyone for the explanations. You learn something new everyday. :-)

[Cindy Glass]

svajjh02,
Please change your name to be compliant with JavaRanch's naming policy.
Your ID should be 2 separate names with more than 1 letter each and not obviously fictional. We would prefer that you use your REAL name.
Thanks,
Cindy