Re: Help finishing excercise using JFrame, JPanel and General Advice

Hi,

I wanted to do abit of programming as a hobby and although have some
experience of non OO languages thought would be a usefull to pick up
Java at the same. To that ends one thing a wrote years ago was a basic
mandelbrot program in BASIC and decided it would be a usefull
excercise once I had got past Hello World and needed something to aim
for. Below is where I've got to so far. It currently calculates
whether one point, hard coded into the program, is within the
mandelbrot set or not and simply displays an empty frame on which I
want to plot the point in a colour of my choosing.

At this point can I say I have trawled net looking at the countless
Mandelbrot examples as well as tutorials on graphics, gui's etc. No
doubt in a few weeks I would have a Eureka moment :) but I am getting
fed up and would appreciate if someone would be kind enough to give me
a leg up.

Q1: Could you have a look at the very end of the code below.
Appreciate the whole design is probably appalling but it would be
really usefull excercise to know what few lines of code of code I
would need just to get the single point on the frame.

Q2: Most of the examples on the net start something like "class
SOMETHING extends JFrame {...etc"

In the simple examples in my text book this superficially looks like a
convenience of being able to say eg. setSize(300,300) instead of
myFrame.setSize(300,00) in my program below. Is that true? If your
program did lots of different things as well as displaying something
on a single frame would you still start it with ...extends JFrame?

Q3: I do want to understand how to complete my program as it is
currently designed but advice as to how it could be redesigned and in
particularly how that design would be better than my first effort
would be great.

Any help very much appreciated,

import java.util.Scanner;
import java.lang.Math;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
import java.awt.Graphics;

class Mandelbrot {

        public static void main(String args[]) {
                Scanner myScanner = new Scanner(System.in);
                double Cxcoord;
                double Cycoord;
                double Zx;
                double Zy;
                double Xtmp;
                double Ytmp;
                double Zmag;
                double a;
                double count;

/* Input the Co-ordinates of the point C on the complex plane we are
testing - C doesn't change */
                System.out.print("Input the Real X Co-ordinate? ");
// Cxcoord = myScanner.nextDouble();
Cxcoord = -0.5;
                System.out.print("The Real X Co-ordinate is: ");
                System.out.println(Cxcoord);

                System.out.print("Input the Imaginary Y Co-ordinate? ");
// Cycoord = myScanner.nextDouble();
Cycoord = 1.0;
                System.out.print("The Imaginary Y Co-ordinate is: ");
                System.out.println(Cycoord);

                System.out.print("The magnitude of Z0 is:");
                a = Math.sqrt((Cxcoord*Cxcoord)+(Cycoord*Cycoord));
                System.out.println(a);
/*
 * CALCULATE WHETHER THE POINT IS IN THE MANDELBROT SET BY INTERATING
THE LOOP BELOW 200 TIMES, IF THE MAGNITUDE IS
 * LESS THAN 2 AFTER 200 ITERATIONS THEN THE POINT IS IN THE
MANDELBROT SET
 *
 */
/* The formula is New Z = (Old Z * Old Z) + C, Z starts out at 0
so...*/
                Zx = Cxcoord; /* initially Z=C */
                Zy = Cycoord;
                count = 0;
                do {
                        count = count + 1;
                        Xtmp = (Zx*Zx)-(Zy*Zy)+Cxcoord;
                        Ytmp = (2*Zx*Zy)+Cycoord;
/* So the new Z value is...*/
                        Zx=Xtmp;
                        Zy=Ytmp;
/* Calculate the magnitude of Z (distance from origin but don't get
confused about this, we're still testing C!!!) */
                        Zmag = Math.sqrt((Zy*Zy)+(Zx*Zx)); // Calculate the magnitude
of Zmag
                } while (count <= 200 && Zmag < 2.0);
/*
 * AT THIS POINT I WILL INSERT CODE TO TEST THE VALUE OF Zmag TO
DETERMINE IF THE POINT IS IN THE MANDELBROT SET AND
 * THE VALUE OF count TO DECIDE ITS COLOUR.
 *
 */
                System.out.print("The Final Magnitude of Z is:");
                System.out.println(Zmag);
                System.out.println(count);
/*
 * AS A START I SIMPLY WANT TO PLOT THE POINT CxCoord AND CyCoord
SOMEWHERE IN THE FRAME I DISPLAY BELOW
 */
                JFrame myFrame = new JFrame();
                String myTitle = "Mandelbrot Frame";
                myFrame.setTitle(myTitle);
                myFrame.setSize(300,300);
                myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

 /* AT THIS POINT I'M STUCK. I NEED TO PLOT THE POINT CxCoord AND
CyCoord IN THE FRAME. I REALISE THAT I NEED
  * TO CONVERT THESE CO-ORDINATES TO INTEGERS TO PLOT IN THE 300x300
FRAME SIZE WHICH I CAN DO. IMAGINE I HAVE DONE
  * THIS AND THEY ARE NOW Xint AND Yint. WHAT DO I DO NEXT!!!???
  *
  * I WANT TO TRY AND USE THE drawLine METHOD AND JUST PLOT A ZERO
LENGTH LINE, SOMETHING LIKE...??????*/
                JPanel panel = new JPanel();
/// Graphics graphic = new Graphics(); GET ERROR "...cannot be
instantiated" OKAY REALISE CAN'T DO THIS!
// HELP!!!

                myFrame.setVisible(true);

        }

}