My paint method partially works. The draw commands inside my loops don't execute. How could I solve this issue?

Question

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.util.ArrayList;
import java.util.Arrays;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class CA extends JFrame
{
    static int[] cells = new int[60];
    static int generation;

    static int[] ruleSet = {0,0,0,0,0,0,0,1};

    int width = 600;
    int w = 15;

    JFrame frame;
    JPanel panel;

    public CA() 
    {
        generation = 0;
        panel = new JPanel();
        this.setSize(1000, 1000);
        this.setVisible(true);
        panel.setLayout(null);
        this.add(panel);
        repaint();
    }

    public static void generate() 
    {
        int[] nextGen = new int[cells.length];
        for(int i = 1; i < cells.length-1; i++) 
        {
            int left = i-1;
            int me = i;
            int right = i+1;
            nextGen[i] = rules(left,me,right);
        }
        for(int i = 0; i < nextGen.length; i++) 
        {
            cells[i] = nextGen[i];
        }
        System.out.println(Arrays.toString(cells));
    }

    public static int rules(int a, int b, int c) 
    {
        if(a == 1 && b ==1 && c == 1)
            return ruleSet[0];
        else if(a == 1 && b ==1 && c == 0)
            return ruleSet[1];
        else if(a == 1 && b ==0 && c == 1)
            return ruleSet[2];
        else if(a == 1 && b ==0 && c == 0)
            return ruleSet[3];
        else if(a == 0 && b ==1 && c == 1)
            return ruleSet[4];
        else if(a == 0 && b ==1 && c == 0)
            return ruleSet[5];
        else if(a == 0 && b ==0 && c == 1)
            return ruleSet[6];
        else
            return ruleSet[7];
    }
    public static void main(String[] args) 
    {
        for(int i = 0 ; i < cells.length; i++) 
        {
            cells[i]=0;
        }
        int num = (int)cells.length / 2;
        cells[num] = 1;
        new CA();
    }

    public void paint(Graphics g) 
    {
        super.paintComponents(g);
        //g2d.drawRect(10, 10, 100, 100);
        //generation = 0;
        System.out.println("generation ......." + generation);
        while(generation < 3) 
        {
            int counter = 0;
            System.out.println("cells...." + Arrays.toString(cells));
            for( int i : cells) 
            {
                if(i == 1) 
                {
                    System.out.println("i == 1");
                    g.fillRect((counter*w) + 300, generation + 300, w, w);
                    //counter++;
                }
                else {
                    System.out.println("not filling rect");
                }
            }
            System.out.println("generation ...in while ...." + generation);
            generate();
            generation++;
        }
        g.drawString("this works", 100, 100);
    }
}

Parts of my paint method work such as the drawString works perfectly fine but all the rest of the paint method does not work the way I want it to. I want to make a Cellular automaton that is similar to the Wolfram cellular automaton. I mostly copied my paint method from other projects that have a working paint method so I don't really know what the method itself is doing.

Answer 1

Your whole approach is broken, and instead I recommend that you follow these guidelines:

• First and foremost draw within the paintComponent method of a JPanel, and be sure to call the same super method within your method override. This is all well described in the Swing drawing tutorials: Lesson: Performing Custom Painting.
• The while loop does not belong within the painting method if your goal is to animate the changes of the display of the cells, and in fact I would venture that your code shouldn't have a while loop
• Instead use a Swing Timer to help you drive your animation. You'd call the next generation within the Timer's ActionListener, and then call repaint() which would signal the JPanel to redraw itself.
• In the paintComponent method, use the state of the cellular automata data to help decide what to draw and where.

Also:

• Never draw directly within a JFrame as this is a complex top-level window container, and drawing directly within it can upset its ability to display the components it holds
• Don't call super.paintComponents within a paint method override. The super call should match the override call in this situation.
• Again you shouldn't even be overriding paint but rather a JPanel's paintComponent method.
• You appear to be covering up your JFrame with the panel JPanel
• Your class extends JFrame, something that you almost never want to do.