what this mean?

[Ernest Lee]

Can anyone explan the following to me??
�protected� means all classes in the same package (like default) and sub-classes in any package can access the features. But a subclass in another package can access the protected members in the super-class via only the references of subclass or its subclasses. A subclass in the same package doesn�t have this restriction. This ensures that classes from other packages are accessing only the members that are part of their inheritance hierarchy.
Thx!

[Guoqiao Sun]

Hi, Ernest, see the following code and try to get the understanding:

//File ClassA.java
package package_a;
public class ClassA
{    
    public static void main(String args[]){ }
    protected void method_in_package_a(){ } 
    
    public void ClassA(){ }
}

package package_b;
import package_a.*;
public class ClassB extends ClassA
{    
    ClassA objA = new ClassA();
    ClassB objB = new ClassB();
    
    void methodA()
    {
        //objA.method_in_package_a(); //not ok
        objB.method_in_package_a();
    }    
}

That means, you can access protected members of superclass by using the reference of its subclass object, not the superclass object itself.
Hope it helps.
Guoqiao

Originally posted by Ernest Lee:
Can anyone explan the following to me??
Protected?means all classes in the same package (like default) and sub-classes in any package can access the features. But a subclass in another package can access the protected members in the super-class via only the references of subclass or its subclasses. A subclass in the same package doesn�t have this restriction. This ensures that classes from other packages are accessing only the members that are part of their inheritance hierarchy.
Thx!

[Gagan Indus]

May this link help a bit :
http://www.javaranch.com/ubb/Forum24/HTML/011669.html
------------------
Gagan (/^_^\)

[Ernest Lee]

Thanks alot!!! Very good explanation and link!