Member Access Rules in JAVA

The member access rules determines whether a sub class can use a property of it's super class or it can only access or it can neither access nor access. There are two level of access control:

• At the top level: public or package-private
• At the member level: public, private, protected

A class may be declared with the 'public' modifier, in that case that class is visible to all classes everywhere.

At the member level, there are three different access modifiers are there: 'private', 'protected' and 'public'.

• private : If private access modifier is applied to an instance variable, method or with a constructor in side a class then they will be accessed inside that class only not out side of the class.

          for example:  class A

                               {

                                        private int x=10;

                               }

                               class B extends A

                               {

                                        int y=20;

                                        System.out.println(x);//Illegal access to x ;

                                }

           If you make any class constructor private, you can't create the instance/object of that class from outside the class. for example:

                                class A

                                {

                                        int x;

                                        private A(int k) // private constructor

                                        {

                                                  x=k;

                                         }

                                }

                                class Test

                                {

                                         public static void main(String args[])

                                         {

                                                  A ob=new A(10); //Compile time error

                                          }

                                }

• protected: If protected access modifier is applied to an instance variable, method or with a constructor in side a class then they will be accessed inside the package only in which class is present and, in addition, by a sub class in another package.

• public: The class, variable, method or a constructor with public access modifier can be accessed from anywhere.