doubt in constructor...

[Ganeshkumar cheekati]

SOURCE:www.javabeat.net

public class Test2l extends Base{
Test2l(long i){
super(2);
}
Test2l()
{
}
public static void main(String args[]){
new Test2l(2);
}
}
class Base{
Base(int i){
System.out.println(i);
}
Base(byte i){
System.out.println(i*2);
}
}

It is giving compilation error as
can not find symbol Base()
In Base class�..
Here I am calling long parameterized constructor in Test2l class only..
But why this error?
Can anyone explain me?

[Seetharaman Venkatasamy]

compiler calls super() inside the Test2l() constructor implicitly. so,it calls Base() which is not there

[Aditya Keyal]

In any derived class if you have a constructor it MUST explicitly call some constructor of the parent class.
If you do not specify then it looks for the default constructor of the Base class.
In your case the default constructor of the Test2 class does not explicitly call the parameterized constructor of the Base class.
Thus the compiler searches for the default which it cannot find and thus the error. Try removing the default constructor or alternatively calling the parameterized constructor from the default. It will work

[Ganeshkumar cheekati]

but here it is invoking parameterized constructor in Test2l i.e Test2l(long)

by using new Test2l(2);

why should it go for default constructor in Test2l?

[Ganeshkumar cheekati]

the compiler add super(); implicitly so it search for default constructor in Base class which is not available
thats why it is showing error..

it doesnot matter which constructor we are invoking we must satisfy compile rules...

am i right?

[James Tharakan]

Yes you are right..

[Vinay Dinakar]

compiler look for default constructor of base class because you used this code .

Test2l()
{
}


remove above line and it will compile properly.

[Bear Bibeault]

"vinay ds", please check your private messages for an important administrative matter.

[Punit Singh]

If you do not call explicitly super(...) from your constructor, then only compiler will add super().

for your code compiler is adding super() in second constructor.

public class Test2l extends Base{
Test2l(long i){
super(2);
}
Test2l()
{
[B]//compiler is adding here
 super();[/B]
}
 
public static void main(String args[]){
new Test2l(2);
}
}