java - Why can't I use protected constructors outside the package?

Question

(This question already has answers here): question from:https://stackoverflow.com/questions/29530199/why-cant-i-use-protected-constructors-outside-the-package

Answer 1

protected modifier is used only with in the package and in sub-classes outside the package. When you create a object using Example ex=new Example(); it will call parent class constructor by default.

As parent class constructor being protected you are getting a compile time error. You need to call the protected constructor according to JSL 6.6.2.2 as shown below in example 2.

package Super;

public class SuperConstructorCall {

    protected SuperConstructorCall() {
    }

}

package Child;

import Super.SuperConstructorCall;

public class ChildCall extends SuperConstructorCall
{

    public static void main(String[] args) {

        SuperConstructorCall s = new SuperConstructorCall(); // Compile time error saying SuperConstructorCall() has protected access in SuperConstructorCall
    }
}

Example 2 conforming to JLS 6.6.2.2:

package Super;

    public class SuperConstructorCall {

    protected SuperConstructorCall() {
    }

}

package Child;

import Super.SuperConstructorCall;

public class ChildCall extends SuperConstructorCall
{

    public static void main(String[] args) {

        SuperConstructorCall s = new SuperConstructorCall(){}; // This will work as the access is by an anonymous class instance creation expression 
    }
}