Question regarding protected access?

[Mohamed Farouk]

   
package parentpackage;

public class Parent {
	public int x1 = 10;
	public void methodX1(){
		
	}
	
	protected int x2 = 10;
	protected void methodX2(){
		
	}
	
	int x3 = 10;
	 void methodX3(){
		
	}
	 private int x4 = 10;
	 private void methodX4(){
		
	}
	
}
 

    
package newpackage;

import parentpackage.Parent;

public class Child extends parentpackage.Parent{
	public static void main(String[] arg){
		parentpackage.Parent p = new Child();
		
		System.out.print(p.x1);
		p.methodX1();
		System.out.print(p.x2);
		p.methodX2();
		System.out.print(p.x3);
		p.methodX3();
	//	System.out.print(p.sx4);
	//	p.smethodX4();

		Child c = new Child();
		System.out.print(c.x1);
		c.methodX1();
		System.out.print(c.x2);
		c.methodX2();

		//System.out.print(p.x3);
		//c.methodX3();
	//	System.out.print(p.sx4);
		//c.smethodX4();

		// System.out.println(p.x);
	}

    

package newpackage;

public class SameParent {
	public int sx1 = 10;
	public void smethodX1(){
		
	}
	
	protected int sx2 = 10;
	protected void smethodX2(){
		
	}
	 
	int sx3 = 10;
	 void smethodX3(){
		
	}
	 private int sx4 = 10;
	 private void smethodX4(){
		
	}
}

  package newpackage;

public class SameChild extends SameParent {
	public static void main(String[] arg) {
		SameParent p = new SameChild();

		System.out.print(p.sx1);
		p.smethodX2();
		System.out.print(p.sx2);
		p.smethodX2();
		System.out.print(p.sx3);
		p.smethodX3();
	//	System.out.print(p.sx4);
	//	p.smethodX4();

		SameChild c = new SameChild();
		System.out.print(c.sx1);
		c.smethodX1();
		System.out.print(c.sx2);
		c.smethodX2();

		System.out.print(p.sx3);
		c.smethodX3();
	//	System.out.print(p.sx4);
		//c.smethodX4();

		// System.out.println(p.x);
	}
}
  

Guys this is simple trying to do some working of access levels of member variables and method in regard to parent and child references.

Everything is clear except for protected access we cannot have a parent reference access the member variables if it is in another package why?
This does not work compile error due to parent reference

    
differentpackage.Parent p = new Child();
System.out.print(p.x2);
		p.methodX2();

whereas this works??

    
SameParent p = new SameChild();
		System.out.print(p.sx2);
		p.smethodX2();

Any reasoning?

[Tom Reilly]

This does not work compile error due to parent reference

Please detail the compiler error.

[Rob Spoor]

Protected members can be accessed from anywhere within the same package. That's why your second example compiles. Protected members can only be accessed by subclasses in different packages if they are their own method. That means an instance of Child can methodX2(), but only using itself (or other instances of Child) as the reference. Using a Parent reference is not allowed.

[Mohamed Farouk]

Hello Rob

That shows a class of you.! I figured that one out later. But thats exactly why it is not compiling. I thaught I would leave it as a lesson for other developers on this hidden subject

Regards
Mohamed