protected static method visibility

[Sarica Ivic]

Hello from Java Junior

Scenario:two classes (super class and subclass) in different packages.
Super class has two protected methods,static and nonstatic method.
Subclass using reference on superclass can "see" protected static method but cannot see non static protected method...

package scjp.staticPlusProtected.package1;

public class Country {

protected static void protectedAndStaticMethod(){}
protected void protectedButNotStatic(){}

}


package scjp.staticPlusProtected.package2;

import scjp.staticPlusProtected.package1.Country;

public class Croatia extends Country {

public static void main(){

Country cr=new Country();
cr.protectedAndStaticMethod();// compiler says OK WHY??
cr.protectedButNotStatic();//---->error..I expected that....The method from the type Country is not visible


Croatia croatia=new Croatia();
Croatia.protectedAndStaticMethod();//OK...static protected member is inherited
croatia.protectedButNotStatic();//OK protected member is inherited


}



So why is it possible to see static protected method of class that is in different package??Thanks

[Prasad Kharkar]

Well this has nothing to do with the static inheritance
static members are imported with the

import static packageName.className.staticMember;
import static packageName.className.*;

your line of code

Country cr=new Country(); // creating a new object is fine, no problem
cr.protectedAndStaticMethod(); // but for a static method, this is actually taken as Country.protectedAndStaticMethod();
//hence whenever you are calling static methods, calling on class name is advised 

also keep in mind that
importing packages means allowing ourselves to write a short name for the class and nothing else

following works fine

package package2;

import package1.Country;
import static package1.Country.*;// this imports all the static members

public class Croatia extends Country {
	public static void main(String args[]){
		
		Country cr = new Country();
		protectedAndStaticMethod();// this call works fine 
			
	}
}

and also without importing the static member i.e. by using the long name of the class and the class member

package package2;

// we have not imported anything here
public class Croatia extends package1.Country { // using the full name 
	public static void main(String args[]){
		package1.Country.protectedAndStaticMethod();// using the full name here
	}
}

hope this helps

[Eric Kizaki]

I played around with your program.

If Croatia does not extend Country the compiler throws the desired error about protected access.
In this case an outside class is creating a class.

If Country does extend Country it does not throw an error with the protected static method.
In this case a subclass is creating its superclass.

Since Croatia is a Country it has access to the class method.

[Eric Kizaki]

Since Croatia is a Country:

Country cr=new Country(); 
cr.protectedAndStaticMethod();// compiler says OK WHY?? 

is the same as:

Country.protectedAndStaticMethod(); //no need to create anything, a class method

If Croatia was not a country you will get protected access error when trying to do either.

[Hareendra Reddy]

Hello prasad...

Static members are not inherited and
does it mean that using protected with static members is similar to using public??

[Abimaran Kugathasan]

Hareendra Reddy wrote:Hello prasad...

Static members are not inherited and
does it mean that using protected with static members is similar to using public??

It is indeed true that static methods are not polymorphic, and you can't override them and get polymorphic behavior. But static methods are inherited in the sense that they're available amongst the child class's methods; you can call a static method using the child class's name, or using an instance of the child class, or without qualification in the body of a child class.

[Eric Kizaki]

Indeed, a subclass has access to all the static methods of the parents. Static methods are methods of the class and since a subclass is that class it has access. Outsider classes can use static methods as utility methods if they are public.

package scjp.staticPlusProtected.package2; 

import scjp.staticPlusProtected.package1.Country; 

public class Croatia extends Country { 

	public static void main(){ 
		Country.protectedAndStaticMethod(); //compiles
		Country.publicAndStaticMethod(); //compiles (I added this method)
	}
}

class Outsider{
	
	public void go(){
		//Country.protectedAndStaticMethod(); //does not compile
		Country.publicAndStaticMethod(); //compiles (I added this method)
	}
}

An outsider class needs public access to the static methods.

[Sarica Ivic]

Thanks everyone...
So conclusion would be:ChildInDifferentPackage can acess parent's public and protected static methods.
And child also gets those methods through inheritance...
And child does not see parent's private and default static methods nor gets them through inheritance.