Access Protection

Java provides four types Access modifiers as public, private, default and protected.  Any variable declared as public, it could be accessed from anywhere.  Any variable declared as private cannot be seen outside of its class.  Any variable declared as default, it is visible to subclasses as well as to other classes in the same package.  Any variable declared as protected, it allows an element to be seen outside of current package, but only to classes that subclass directly.

	public	private	default	protected
Same class	Yes	Yes	Yes	Yes
Same package sub class	Yes	No	Yes	Yes
Same package non-subclass	Yes	No	Yes	Yes
Different package sub class	Yes	No	No	Yes
Different package non-subclass	Yes	No	No	No

Example:

package p1;

public class protect

{

            int n=1;

            private int n_pri=2;

            protected int n_pro=3;

            public int n_pub=4;

            public protect()

            {

            System.out.println("Super constructor");

            System.out.println("default="+n);

            System.out.println("private="+n_pri);

            System.out.println("protected="+n_pro);

            System.out.println("pubic="+n_pub);

            }

}

package p1;

class derive extends protect

{

            derive()

            {

            System.out.println("Sub constructor");

            System.out.println("default="+n);

            //System.out.println("private="+n_pri);

            //since it is a private variable in package p1

            System.out.println("protected="+n_pro);

            System.out.println("pubic="+n_pub);

            }

}

import p1.protect; 

class same

{

            public static void main(String[] args)

            {

                        protect obj=new protect();

            }

}