Please Help Me To Clear My Doubt?

[V. Potluri]

Hi,

Under what circumstances, we can declare constructor of a class as a protected?

    
 
    public class Test {
 
      protected Test(){
 
      }
 
      public static void main(String[] args) {
 
      }
    }
 

According to my knowledge, constructor never participate in inheritance, then under what circumstances we have to declare constructor as protected?

Thanks in advance,

Regards,
Gopal

[Harshit Rastogi]

I am not sure , but If you try to access the class from different package , the class will be accessible but it will not create the object as constructor declared is protected.

check for this condition.

[Henry Wong]

According to my knowledge, constructor never participate in inheritance, then under what circumstances we have to declare constructor as protected?

What do you mean by "never participate in inheritance"? While it is true that a constructor can't be overridden, but it can be called from the subclass. Hence, you need to define access to it -- be it from the subclass or any class that uses it.

Henry

[Ankit Garg]

What do you mean by this

under what circumstances we have to declare constructor as protected?

You are not forced to do so...

however, if you declare all the constructors of a class as protected, then you can sub-class it in different packages, but you cannot create instances of the class outside the package....

[V.G. Hindriksen]

When this can be used?
I think in the case you *prefer* it to be subclassed, so abstract is too much. Think about a colleague who hates almost empty subclasses and does not want to extend your abstract Animal-class; you change it this way, explaining public was too much with good reasons, and go on with your work.

Probably you'll only use private and default and coderanch. Java-engineers did not make the language on usage-statistics, but only left parts out which could lead to problems (such as multiple extension). So the question is the reverse: why wouldn't it be possible to make a class-instantiation protected?

[M Srilatha]

if the constructor of a class is declared as protected, objects of that class cannot be created outside its package.
And constructors will play a role in inheritance also. Only thing is that constructors are not inherited. A call to the super class constructor will be added in the constructor of the subclass by the compiler if the default constructor is there otherwise you will have to add the same.(ofcourse if there is a call to this(), call to super class constructor is not required.)

[Anoobkumar Padmanabhan]

One thing added to SRILATHA

A call to the super class constructor will be added in the constructor of the subclass by the compiler if the default constructor is there otherwise you will have to add the same.(ofcourse if there is a call to this(), call to super class constructor is not required.)

The compiler will add a call to the default constructor of the superclass, when it finds a constructor. ie, it will add a super(), as the first line of the constructor.

when a call to this() is given, the compiler will go for the default constructor of the same class. since it can't contain a call to this() again(Recursive Contructor invocation error), the first line added will be super(). so it will perform the functionality implicitly.

[V. Potluri]

Hi,

Thanks a lot for each of you for spending your precious time for clearing my doubt.

Have a wonderful day ahead!

Regards,
Gopal