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I am trying to make a replica of the Game of Life using swing, I admit i have used code from some 1 else as i am trying to get my head around it and then proceed with my own implementation. I have some understanding of their code, yet i wanted to implements 2 additional features to their code. However i am finding that the way it is written is posing problems as i wanted to add a MouseListener(To make a cell come to life when clicked) and WindowListener(To make a start,pause and resume button).

I do understand how they work to some extent, yet i need your help to get my headaround it.

Here is the code:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.beans.Transient;
import java.util.Random;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;


@SuppressWarnings("serial")
public class ConwaysGameOfLife extends JPanel implements MouseListener{

    private int[][] cellsGrid; // grid is the size of the 2d array
    private static final Random rnd = new Random(); // make a new random generator
    private int generationCounter; // counter for the generation

    public ConwaysGameOfLife(int width, int height) {
        this.cellsGrid = new int[width / 4][height / 4];// divides by 4 whatever the width and height set is 
        setupGrid();
    }// new method for creating the game with input sizes for the size of the game window

    /*The grid consists fully of cells, the grid size is divided by 4 to make the cells
     * setupGrid makes the grid of cells
     * 
     * */
    private void setupGrid() {
        for (int[] row : cellsGrid) {
            for (int j = 0; j < row.length; j++) {
                if (rnd.nextDouble() < 0.92)
                    continue;
                row[j] = rnd.nextInt(2);
                //
            }
        }
    }
    /*
     * applies the rule to the existing cells changing their state depending on the position to neighbors set in the rules
     * */
    public void updateGrid() {
        for (int i = 0; i < cellsGrid.length; i++) {
            for (int j = 0; j < cellsGrid[i].length; j++) {
                applyRule(i, j);
            }
        }
    }

    // Rules of game of life cells iterations
    private void applyRule(int i, int j) {
        int left = 0, right = 0, up = 0, down = 0;
        int dUpperLeft = 0, dUpperRight = 0, dLowerLeft = 0, dLowerRight = 0;
        //this shows the 8 possible neighbors in terms of position

        if (j < cellsGrid.length - 1) {
            right = cellsGrid[i][j + 1];
            if(i>0)
                dUpperRight = cellsGrid[i - 1][j + 1];
            if (i < cellsGrid.length - 1)
                dLowerRight = cellsGrid[i + 1][j + 1];
        }

        if (j > 0) {
            left = cellsGrid[i][j - 1];
            if (i > 0)
                dUpperLeft = cellsGrid[i - 1][j - 1];
            if (i< cellsGrid.length-1)
                dLowerLeft = cellsGrid[i + 1][j - 1];
        }

        if (i > 0)
            up = cellsGrid[i - 1][j];
        if (i < cellsGrid.length - 1)
            down = cellsGrid[i + 1][j];

        int sum = left + right + up + down + dUpperLeft + dUpperRight
                + dLowerLeft
                + dLowerRight;

        if (cellsGrid[i][j] == 1) {
            if (sum < 2)
                cellsGrid[i][j] = 0;
            if (sum > 3)
                cellsGrid[i][j] = 0;
        }

        else {
            if (sum == 3)
                cellsGrid[i][j] = 1;
        }

    }

    @Override
    @Transient
    public Dimension getPreferredSize() {
        return new Dimension(cellsGrid.length * 4, cellsGrid[0].length * 4);
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Color gColor = g.getColor();

        g.drawString("Generation: " + generationCounter++, 0, 10);
        for (int i = 0; i < cellsGrid.length; i++) {
            for (int j = 0; j < cellsGrid[i].length; j++) {
                if (cellsGrid[i][j] == 1) {
                    g.setColor(Color.black); // change colour
                    g.fillRect(j * 8, i * 8, 8, 8); // change size of cells
                }
            }
        }

        g.setColor(gColor);
        //paint the cells to a colour
    }

    public static void main(String[] args) {
        final ConwaysGameOfLife c = new ConwaysGameOfLife(800, 800);
        JFrame frame = new JFrame();
        frame.getContentPane().add(c);
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationByPlatform(true);
        frame.setVisible(true);

        JButton start=new JButton("START");
        /* This method specifies the location and size
         * of button. In method setBounds(x, y, width, height)
         * x,y) are cordinates from the top left 
         * corner and remaining two arguments are the width
         * and height of the button.
         */
        start.setBounds(80,0,80,20);

        //Adding button onto the frame
        //frame.add(start);

        new Timer(100, new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                frame.add(start);
                c.updateGrid();
                c.repaint();
            }
        }).start();
    }


    @Override
    public void mouseClicked(MouseEvent e) {
        // TODO Auto-generated method stub



    }

    @Override
    public void mouseEntered(MouseEvent e) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseExited(MouseEvent e) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mousePressed(MouseEvent e) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseReleased(MouseEvent e) {
        // TODO Auto-generated method stub

    }
}

First of all, The button flickers, and only appears when hovered over with the mouse, still flickering. Then i want the iterations to begin after start button is pressed, and pause button to pause it, and resume(Have a decent idea how it would work, but not how to implement it with the structure of swing that is done in this code.)

Secondly, I wanted the cells to come to life when they are pressed with the mouse, But, i am unsure how to implement the mouseListener to do this.

I tried something like cellsGrid[i][j] = 1; when clicked by mouse but i get errors, which is due to my lack of understanding of the implementation of cellsGrid.

I am not expecting solutions to the problem, I would like some guidance to understand the Listeners better and maybe how to make this simpler to understand for me. Thank You :)

Bart123
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    you are adding your "start" button every 100 ms, that might not be what you want, since you put the code inside the refresh timer "loop". that might cause some flickering, but it might also be to the double buffered components of swing elements. – xander Mar 13 '17 at 15:00
  • Welcome to Stack Overflow! Please take the [tour](http://stackoverflow.com/tour), have a look around, and read through the [help center](http://stackoverflow.com/help), in particular [How do I ask a good question?](http://stackoverflow.com/help/how-to-ask) and [What topics can I ask about here?](http://stackoverflow.com/help/on-topic). - Pleasepost only code you have full copyright to do so. Then: please post the *complete* errormessage you get and mark the lines in your example the error messages line numbers refer to. – Timothy Truckle Mar 13 '17 at 15:01
  • When it is placed outside, it still flickers, which part is doublebuffered by swing? – Bart123 Mar 13 '17 at 15:35
  • 1) Tip: Add @xander (or whoever, the `@` is important) to *notify* the person of a new comment. 2) See also this [working example of GOL](http://stackoverflow.com/a/8200046/418556). – Andrew Thompson Mar 13 '17 at 15:36

1 Answers1

1

Your simulation has a model that is a grid of cells; it has a view that paints an 8 x 8 square to represent a cell in the grid. As suggested here, you can map model and view coordinates using linear interpolation. In particular, given the following proportions, you can cross-multiply and solve for the missing coordinate.

view.x : panelWidthInPixels :: model.x : modelXRange
view.y : panelHeightInPixels :: model.y : modelYRange

For reference, this complete example maps mouse coordinates to pixel coordinates in an image. A complete example of John Conway’s Game of Life in Java Swing is cited here.

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trashgod
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