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15.3.1 Access specifiers
                 The visibility range of the access specifiers in a package is given below.

                          Access Specifiers   Same class       Same package     Subclass in the   Outside package
                                                                                outside package
                         public            Yes               Yes              Yes               Yes
                         protected         Yes               Yes              Yes               No
                         default           Yes               Yes              No                No
                         private           Yes               No               No                No

                 Let us do some programs on package.


                  Program 1      Write a program to create a package Eleven containing class Distance having the following
                                 specifications.
                                 Package                          :   Eleven
                                 Class name                       :   Distance
                                 Data Members
                                 double x1, y1, x2, y2            :   Co-ordinates of two points
                                 Member Methods
                                 Diatance(double x11, double y11,   :   Constructor to assign the data members
                                 double x21, double y21)
                                 double  calDistance()            :     Calculates  and  returns  the  distance  between  two
                                                                     points using formula
                                                                     √(x2-x1)  + (y2-y1) 2
                                                                             2
                                 Write a second class Circle to import Distance and calculate the radius of a circle by method
                                 calDistance(), where the two-point co-ordinates are given. Finally, print the area of the circle
                                        2
                                 as A=πr  in function areaCircle().
                   1      package Eleven;    // package declaration
                   2      public class Distance

                   3      {
                   4        double x1,x2,y1,y2;

                   5        public Distance(double x11,double y11,double x21,double y21)
                   6        { x1=x11;

                   7          y1=y11;
                   8          x2=x21;

                   9          y2=y21;
                  10        }
                  11

                  12        public double calDistance()

                  13        { return Math.sqrt(Math.pow((x2-x1),2)+Math.pow((y2-y1),2));
                  14        }
                  15      }



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