Constructot Doubt

[Vijay Arora]

There is compilation error in the Code.Why???
class Animal
{
Animal(String name)
{
System.out.println("ANIMAL NAME="+name);
}
}
class Dog extends Animal
{
Dog(String h)
{
}

}
public class Three{
public static void main (String [] args)
{
new Animal("Giraffe");
}
}

[Hemnathbabu Kottaiveedu]

There is compilation error in the Code.Why???

Can you please tell us the exact error which you got when you try to compile the the above code and your interpretation of the error.

[Tusshar Fasate]

you just change your code like this...

Dog(String h)
{
super(h);
}


now your code will run.

[Vijay Arora]

I got this compilation error:
can not find symbol:constructor Animal()

[Deepak Bala]

Originally posted by Albert:
I got this compilation error:
can not find symbol:constructor Animal()

Please quote your source when you display code. This appears to be from my exam. Please also change your name to reflect javaranch naming standards. You need a first and last name

Any class that extends from another will try to run its default constructor. If you dont have that it will throw a compile time error.

[priya shende]

hi tushar,
Super class dont know about child class.There is a simple class Animal and having one constructor and we are calling constructor in main()function with proper argument.Then why the code is giving comile time error that can't find symbol.

thanks,
priya.

[Mustafa Musaji]

Dog extends Animal, and before a Dog can be constructed, its parent must be. In your code even though it is not typed, the compiler puts in a super() call to a default Animal constructor which doesn't exist (hence the error).

  
class Animal{
  //if you had a no args constructor you're original code would compile
  //Animal() {
  //}
  
  Animal(String name){
    System.out.println("ANIMAL NAME="+name);
  }
}
 
class Dog extends Animal{
  Dog(String h){
  super(); //currently looks like this
  //super(h); //should look like this
  }
}
 

public class Three{
  public static void main (String [] args){
    new Animal("Giraffe");
  }
}

[priya shende]

Thanks Mustafa.
-----------------
Studying for SCJP.

[Tusshar Fasate]

Hi Priya,
You are right.
I had also thought when i first saw the question but after contemplating over the question i found the problem.
we know that ,Compiler checks grammare of language.
So even we are not bothering with any other class except Animal in main,it will give error because we are not calling super class constructor.
Whatever mustafa is saying its true.


Tushar
SCJP5.0
Pune
India.

[Ben Souther]

"Albert",
Please check your private messages.
-Ben

[Madhukar Ojha]

In your Animal class there is only one parameterized constructor .
Just modify your Dog class
class Dog{
Dog(String h){
super(h);
}
}

or modify your Animal class
just add default constructor to it .