// Point3.java // Point class declaration represents an x-y coordinate pair.

// Point3.java// Point class declaration represents an x-y coordinate pair.public class Point3 {private int x; // x part of coordinate pairprivate int y; // y part of coordinate pair// no-argument constructorpublic Point3(){// implicit call to Object constructor occurs here} // constructorpublic Point3( int xValue, int yValue ){// implicit call to Object constructor occurs herex = xValue; // no need for validationy = yValue; // no need for validation} // set x in coordinate pairpublic void setX( int xValue ){x = xValue; // no need for validation} // return x from coordinate pairpublic int getX(){return x;} // set y in coordinate pairpublic void setY( int yValue ){y = yValue; // no need for validation} // return y from coordinate pairpublic int getY(){return y;} // return String representation of Point3 objectpublic String toString(){return "[" + getX() + ", " + getY() + "]";} } // end class Point3// Circle4.java// Circle4 class inherits from Point3 and accesses Point3's// private x and y via Point3's public methods.public class Circle4 extends Point3 {private double radius; // Circle4's radius// no-argument constructorpublic Circle4(){// implicit call to Point3 constructor occurs here} // constructorpublic Circle4( int xValue, int yValue, double radiusValue ){super( xValue, yValue ); // call Point3 constructor explicitlysetRadius( radiusValue );} // set radiuspublic void setRadius( double radiusValue ){radius = ( radiusValue < 0.0 ? 0.0 : radiusValue );} // return radiuspublic double getRadius(){return radius;} // calculate and return diameterpublic double getDiameter(){return 2 * getRadius();} // calculate and return circumferencepublic double getCircumference(){return Math.PI * getDiameter();} // calculate and return areapublic double getArea(){return Math.PI * getRadius() * getRadius();} // return String representation of Circle4 objectpublic String toString(){return "Center = " + super.toString() + "; Radius = " + getRadius();} } // end class Circle4// CircleTest4.java// Testing class Circle4.import java.text.DecimalFormat;import javax.swing.JOptionPane;public class CircleTest4 {public static void main( String[] args ) {// instantiate Circle objectCircle4 circle = new Circle4( 37, 43, 2.5 ); // get Circle4's initial x-y coordinates and radiusString output = "X coordinate is " + circle.getX() +"nY coordinate is " + circle.getY() +"nRadius is " + circle.getRadius();// set new x-coordinate// set new y-coordinatecircle.setRadius( 4.25 ); // set new radius// get String representation of new circle valueoutput += "nnThe new location and radius of circle aren" +circle.toString();// format floating-point values with 2 digits of precisionDecimalFormat twoDigits = new DecimalFormat( "0.00" );// get Circle's diameter