The Java Program: Circle.java

  1 // Circle.java
  2 
  3 class Circle {
  4 
  5    // instance variables
  6    final Point2D center;
  7    final double radius;
  8 
  9    // constructors
 10    Circle (Point2D c, double r) { center=c; radius=r; }
 11    Circle (Point2D c)           { this (c, 1.0); }
 12    Circle (double r)            { this (new Point2D (0.0, 0.0), r); }
 13    Circle ()                    { this (1.0); }
 14 
 15    // methods
 16    double circumference () {
 17       return 2.0*Math.PI*radius;
 18    }
 19 
 20    double area () {
 21       return Math.PI*radius*radius;
 22    }
 23 
 24 }