Why can't I use protected constructors outside the package for this piece of code:
package code;
public class Example{
protected Example(){}
...
}
Check.java
package test;
public class Check extends Example {
void m1() {
Example ex=new Example(); //compilation error
}
}
- Why do i get the error even though i have extended the class?
Please explain
EDIT:
Compilation error:
The constructor Example() is not visible
Answer
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
}
}
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