Overridden methods run like an abstract method

Question

public class Mammal
public int length;
public Mammal(int b)
this.length=b;
public void speciesName()
System.out.println("I am a mammal");
public class Cat extends Mammal
public Cat (int b)
super(b);
public void speciesName()
System.out.println("I am a Cat");
public class Goat extends Mammal
public Goat(int b)
super(b);
public void speciesName()
System.out.println("I am a Goat");
public class Test
public static void main(String[] args)
Cat k=new Cat(50);
Goat g=new Goat(60);
Vector<Mammal> v=new Vector<Mammal>();
v.add(k);
v.add(g);
Mammal m; //reference
m=v.elementAt(0);
m.speciesName();
m=v.elementAt(1);
m.speciesName();
hello all,
my problem about above code is:
on the console : I am a Cat
I am a Goat
but i did not understand why the result is so this.
i thought that the screen output must be : I am a Mammal
I am a Mammal
i supposed that Mammal class's speciesName() method must run.
if speciesName() was abstract method, i could understand the result.
but in this situation, i didn't understand how the output is this.
thanks...

Answer 1

khanD wrote:
i thought that the screen output must be : I am a Mammal
I am a Mammal
i supposed that Mammal class's speciesName() method must run.
if speciesName() was abstract method, i could understand the result.
but in this situation, i didn't understand how the output is this.Now you know that it doesn't matter whether speciesName in Mammal is abstract or not. Overriding works the same regardless.
But there are other differences. For example right now Mammal is concrete so you could create a Mammal object if you wanted. If you made speciesName abstract that would no longer be possible. Right now you also don't have to override speciesName in the subclasses. If speciesName were abstract you would have to do that.