HELLO Im New Here! ..and having problems about this ..I am doing #2 which requires #1. And im done with my code. and i have this little confuse about the Cylinder class here's the question :
[QUOTE][I]3. Every cylinder has a base and height, where the base is a circle. Design the class CYLINDER that can capture the properties of a cylinder and perform the usual operations on a cylinder. Derive this from the class CIRCLE designed in No.2. Some operations that can be performed by the cylinder are as follows: calculate and print the volume, calculate and print the surface area, set the height, set the radius of the base, and set the center of the base. [/i][/quote]
Im confuse about this because of Polymorphism.. I miss the lecture because im late..but im doing a self study but about this problem i cant understand and do the coding.. but i have already done in inheritance the questions & coding of 1 and 2.. here is my code for #1
[I]This is for Point.java[/i]

class Point
{
    // Declare variables
    private double x;
    private double y;

    // Empty constructor
    public Point()
    {
    }

    // Constructor with variables
    public Point(double x, double y)
    {
        this.x = x;
        this.y = y;
    }

    // Used to set the new x-coordinate
    public void setX(double x)
    {
        this.x = x;
    }

    // Used to set the new y-coordinate
    public void setY(double y)
    {
        this.y = y;
    }

    // Used to display the x-coordinate
    public double getX()
    {
        return x;
    }

    // Used to display the y-coordinate
    public double getY()
    {
        return y;
    }
}

[I]This is for the Circle.java which extends Point.java[/i]

import java.lang.*;
 
public class Circle extends Point
{
    // Declare variables
    private double r;
     
    // Empty constructor
    public Circle()
    {
    }
     
    // Constructor with variables
    public Circle(double x, double y, double r)
    {
        super(x, y);
        this.r = r;
    }
     
    // Used to set the radius
    public void setR(double r)
    {
        this.r = r;
    }
     
    // Used to return the radius
    public double getR()
    {
        return r;
    }
     
    // Calculates the area
    public double area()
    {
        return Math.PI*r*r;
    }
     
    // Calculates the circumference
    public double circumference()
    {
        return 2*Math.PI*r;
    }
}

[I]And Ive created a class to test my Code which i named Tester.java[/i]

import java.util.*;

public class Tester
{
    static Scanner console = new Scanner(System.in);
    public static void main(String[] args)
    {
        // Declare variables
        int loopDecision, xC, yC, rC;

        // Loop statement
        System.out.println("Enter 1 to insert your own values. " +
                                    "Enter 2 to use preset values.");
        loopDecision = console.nextInt();

        /* If 1 is chosen then it goes into the if loop.
         * In the if loop the user will be able to set their
         * own coordinates and radius. They will then get the
         * area of the circle and the circumference. */
        if(loopDecision == 1)
        {
            // Ask user to input values
            System.out.println("Enter a number 1-10 for the X coordinate.");
            xC = console.nextInt();
            System.out.println("Enter a number 1-10 for the Y coordinate.");
            yC = console.nextInt();
            System.out.println("Enter the radius.");
            rC = console.nextInt();
            System.out.println();

            // Set the Circle class.
            Circle p = new Circle(xC, yC, rC);

            // Display their entered values
            System.out.println("X coordinate = " + p.getX());
            System.out.println("Y coordinate = " + p.getY());
            System.out.println();

            // These two for loops display the values on the side and bottom

            for(int i = 10; i > 0; i--)
            {
                System.out.println(i);
            }
            for(int i = 1; i <= 10; i++)
            {
                System.out.print(" " + i);
            }

            System.out.println();
            System.out.println("Radius = " + p.getR());
            // Display the area and circle
            System.out.println("Area of the circle = " + p.area());
            System.out.println("Circumference of the circle = " + p.circumference());
        }

        /* In the else loop the user will be able to see
         * the varius functions of the program. Using preset
         * values assigned by me. */
        else
        {
            // Set the values
            Circle p = new Circle(10, 3, 5);
            System.out.println();

            // Display the starting values
            System.out.println("Initial x-coordinate = " + p.getX());
            System.out.println("Initial y-coordinate = " + p.getY());
            System.out.println();

            // These two for loops display the values on the side and bottom
            for(int i = 10; i > 0; i--)
            {
                System.out.println(i);
            }
            for(int i = 1; i <= 10; i++)
            {
                System.out.print(" " + i);
            }

            System.out.println();
            System.out.println("Initial radius = " + p.getR());

            System.out.println();
            System.out.println("Now changing the values.");
            System.out.println();

            // Set new values
            p.setX(5);
            p.setY(10);
            p.setR(4);

            // Display the new values
            System.out.println("X coordinate = " + p.getX());
            System.out.println("Y coordinate = " + p.getY());
            System.out.println();

            // These two for loops display the values on the side and bottom
            for(int i = 10; i > 0; i--)
            {
                System.out.println(i);
            }
            for(int i = 1; i <= 10; i++)
            {
                System.out.print(" " + i);
            }

            System.out.println();
            System.out.println();
            System.out.println("Radius = " + p.getR());
            // Show area and circumference with the new values
            System.out.println("Area of the circle = " + p.area());
            System.out.println("Circumference of the circle = " + p.circumference());
        }
    }
}

[I]Any help i appreciated about this.. thank you..[/i]
[I]And can you re-check my code if it is correct?..[-O<[/i]