Overriding/overloading.

[Tony King]

Hi, I don' t understand why the following code prints "Scale Shape". This example is about overloading (not ovveriding) and I supposed that it prints "Scale Circle"..

  
public class Circle extends Shape
{
   public void scale(int x)
   {
     System.out.println("Scale Circle");
   }

   public static void main(String args[])
   {
     Shape s = new Circle();
     s.scale(1);
   }
}


class Shape
{
  public void scale(long x)
  {
  System.out.println("Scale Shape");
  }
}

tks
bye

[Siva Masilamani]

here the scale method is not overriden instead overloaded.

So overloaded method is resolved at compile time and hence it does not depends on the object at runtime.

Compiler resolve the method at runtime only if the method is overriden.

So the compiler will call the method based on reference.

[Tony King]

Ok, thanks!

I did not know that compiler resolve the method at runtime ONLY if the method is overriden.

Bye

[Seetharaman Venkatasamy]

Siva Masilamani wrote:
Compiler resolve the method at runtime only if the method is overriden.

No, Compiler is not at all related to the runtime.[This is Overloading . not an overridding]so, in Shape class there is no scale(int) mothod. so compiler complaint.

is it make sense?

[Siva Masilamani]

Ok

i have to change my Word like this because compile has nothing to do at run time.

so

Compiler resolve the method at runtime only if the method is overriden

should be something like this.

the determination of which overridden method to execute isn't made until runtime

[Seetharaman Venkatasamy]

Siva Masilamani wrote:the determination of which overridden method to execute isn't made until runtime

Once again, i tell you.it is not an Overriding.still you need to change your sentence

[Tony King]

Now I'm confused..
Can you help me???

[Seetharaman Venkatasamy]

Tony King wrote:Now I'm confused..

why you confused ?

[Garlapati Ravi]

what ever it may be, i have learned a new point today.

[Siva Masilamani]

seetharaman venkatasamy wrote:

Siva Masilamani wrote:the determination of which overridden method to execute isn't made until runtime

Once again, i tell you.it is not an Overriding.still you need to change your sentence

That sentence is not particular for his program.

It is in general that overriden method will be resolved at runtime and overloaded method will be resolved by the compiler,that is compiler knows which overloaded method to be called.

So in his program it is overloaded and hence the method call is based on reference not on actual object

To put it in simple words.

If method is overloaded check the reference and if the method is present then no error and the method will be called based on reference.

If the method is overriden check the reference and if the method is present on that reference then no error but the method call will be based on object at runtime not on reference type.

The above conditions hold good only for instance method not for class method.

Also any variable(class or instance) always refered with reference type not on object type.
Hope it clears everyone confusion

[Tony King]

Yes, now the concept is clear. Thank you, the answer is exhaustive!

bye