Enum - Constant Specific Class Body

[Faber Siagian]

enum Horse 
{
PONY(10),
ICELANDIC(13) 
{ 
int height = 100; //line 6
public int getWeight() { return 800; } 
},

HORSE(15); 
Horse(int hands) { this.height = hands; this.weight = hands * 100; } 
int height; int weight; 
int getWeight() { return weight; } 
void setWeight(int w) { weight = w; } 
} 
 
class Stable 
{ 
public static void main(String [] hay) 
{ 
Horse h = Horse.ICELANDIC; 
System.out.println(h.getWeight() + " " + h.height); //output : 800 13
} 
} 

I expect the result : 800 100, because ICELANDIC has its own height.
But actually it is 800 13. Would someone explain this?

[Santhosh Kumar]

Variables cannot be overriden by the subclasses and are always referred through the type of the reference rather than the instance of the reference.

In your case, ICELANDIC is an instance of subclass of Horse and others are just instances of Horse. However you are referring to all the instances through Horse type reference so variables value would be from Horse type (not based on the actual instance type). Check out these simple classes, and you might get some idea.

  
 
class A {
    public int number = 10;
 
    public int getNumber() {
        return 10;
    }
}
 
class B extends A {
    public int number = 20;
 
    @Override
    public int getNumber() {
        return 20;
    }
}
 
public class ABTest {
 
    public static void main(String[] args) {
 
        A pureA = new A();
        A bAsA = new B();
        B pureB = new B();
 
        System.out.println("Pure A: " + pureA.number + " " + pureA.getNumber());
        System.out.println("B As A: " + bAsA.number + " " + bAsA.getNumber());
        System.out.println("Pure B: " + pureB.number + " " + pureB.getNumber());
    }
}
 

The output is

 
Pure A: 10 10
B As A: 10 20
Pure B: 20 20

[ July 09, 2008: Message edited by: Santhosh Kumar ]

[Faber Siagian]

Hi Santhosh, great. Thanks.

[Milan Sutaria]

Nice Question & great Reply ... thanks
I thought of playing with it a bit

enum Horse {
PONY(10),
ICELANDIC(13) { 
int height = 100; //line 6
public int getWeight() { return [B][B][I]height+2[/I][/B][/b]; } // output 102 13
},

HORSE(15); 
Horse(int hands) { this.height = hands; this.weight = hands * 100; } 
int height; 
int weight; 
int getWeight() { return weight; } 
void setWeight(int w) { weight = w; } 
}  

class B { 
public static void main(String [] hay) { 
Horse h = Horse.ICELANDIC; 
System.out.println(h.getWeight() + " " + h.height); 
} 
} 

[ July 10, 2008: Message edited by: neo Tux ]