Question

Problem 3.2 (Please download Point.java to complete this problem)

Every circle has a center and radius. Given the radius, we can determine the circle’s area and circumference. Given the center, we can determine its position in the x-y plane. The center of a circle is a point in the x-y plane. Please do the following:

1. Design the child class Circle that can store the radius and the center of the circle based on the class Point we talked in the class. You should be able to perform the usual operation on a circle, such as setting radius, printing the radius, calculating and printing the area and circumference, and carrying out the usual operations on the center.
2. Write a test program to test your program

Here is the Point.Java program:

// class Point

public class Point
{
        protected double x, y; // coordinates of the Point

                //Default constructor
        public Point()
        {
        setPoint( 0, 0 );
        }

                //Constructor with parameters
        public Point(double xValue, double yValue )
        {
        setPoint(xValue, yValue );
        }

                // set x and y coordinates of Point
        public void setPoint(double xValue, double yValue )
        {
        x = xValue;
        y = yValue;
        }

                // get x coordinate
        public double getX()
        {
        return x;
        }

                // get y coordinate
        public double getY()
        {
        return y;
        }

                // convert point into String representation
        public String toString()
        {
        return "[" + String.format("%.2f", x)
               + ", " + String.format("%.2f", y) + "]";
        }

     //Method to compare two points
        public boolean equals(Point otherPoint)
        {
        return(x == otherPoint.x &&
               y == otherPoint.y);
        }

     //Method to compare two points
        public void makeCopy(Point otherPoint)
        {
        x = otherPoint.x;
        y = otherPoint.y;
        }

        public Point getCopy()
        {
        Point temp = new Point();

        temp.x = x;
        temp.y = y;

        return temp;
        }

                // print method
        public void printPoint()
        {
        System.out.print("[" + String.format("%.2f", x)
                       + ", " + String.format("%.2f", y) + "]");
        }

}  // end class Point

Answer 1

// class Point

class Point
{
protected double x, y; // coordinates of the Point

//Default constructor
public Point()
{
setPoint( 0, 0 );
}

//Constructor with parameters
public Point(double xValue, double yValue )
{
setPoint(xValue, yValue );
}

// set x and y coordinates of Point
public void setPoint(double xValue, double yValue )
{
x = xValue;
y = yValue;
}

// get x coordinate
public double getX()
{
return x;
}

// get y coordinate
public double getY()
{
return y;
}

// convert point into String representation
public String toString()
{
return "[" + String.format("%.2f", x)
+ ", " + String.format("%.2f", y) + "]";
}

//Method to compare two points
public boolean equals(Point otherPoint)
{
return(x == otherPoint.x &&
y == otherPoint.y);
}

//Method to compare two points
public void makeCopy(Point otherPoint)
{
x = otherPoint.x;
y = otherPoint.y;
}

public Point getCopy()
{
Point temp = new Point();

temp.x = x;
temp.y = y;

return temp;
}

// print method
public void printPoint()
{
System.out.print("[" + String.format("%.2f", x)
+ ", " + String.format("%.2f", y) + "]");
}

} // end class Point

class Circle
{
   private double radius;
   private Point p;
  
   public Circle(Point p, double radius)
   {
       this.p = p;
       this.radius = radius;
   }
   public void setRadius(double radius)
   {
       this.radius = radius;
   }
   public double getRadius()
   {
       return radius;
   }
   public double getArea()
   {
       return 3.14*radius*radius;
   }
   public double getCircumference()
   {
       return 2*3.14*radius;
   }
   public void printCircle()
{
System.out.print("Center :");
p.printPoint();
System.out.println(" Radius : "+radius +" Area : "+getArea() +" Circumference : "+getCircumference());
  
  
}
  
}
class Test
{
   public static void main (String[] args)
   {
       Point center = new Point(5.5, 4.7);
       Circle c = new Circle(center, 10.00);
      
       c.printCircle();
      
      
      
   }
}

Output:

Center :[5.50, 4.70] Radius : 10.0  Area : 314.0  Circumference : 62.800000000000004

Do ask if any doubt. Please up-vote.