drawing a centered grid with JFrame

[adonaldson]

I am trying to figure out how to draw a grid that is prompted by the user on how many squares wide and high. With a 10% boarder that resizes with the window.

I have it working up to an xy axis in the window.

How do I get it to make a grid of even squares?

package gridWindow;

import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import java.util.Scanner;

public class GridWindow extends JFrame {

    private static final int FRAME_SIZE = 500;
    private static final int MAX_NUM = 40;
    private static final int MIN_NUM = 10;
    private static int numberOfLines;
    

    public static void main(String[] args) {
       GridWindow guiWindow = new GridWindow();
        guiWindow.setSize(FRAME_SIZE, FRAME_SIZE);
        guiWindow.setDefaultCloseOperation(EXIT_ON_CLOSE);
        Scanner keyboard = new Scanner(System.in);
        String valueString;


        //Error check loop

        do {
            valueString = JOptionPane.showInputDialog("Enter the number of lines in the grid (10-40): ");
            guiWindow.numberOfLines = Integer.parseInt(valueString);

        } while (numberOfLines < MIN_NUM || numberOfLines > MAX_NUM);

        guiWindow.setVisible(true);

    }

    @ Override
    public void paint(Graphics g) {
        super.paint(g);
                
        Graphics canvas = getContentPane().getGraphics();
        int width = this.getContentPane().getWidth();
        int height = this.getContentPane().getHeight();
        
        double boarder = width*0.1;
        int sideBoarder = (int)boarder;
       
       

        canvas.drawLine(width/2, sideBoarder , width/2, height-sideBoarder);
        canvas.drawLine(sideBoarder, height/2, width-sideBoarder, height/2);
    }
}

Thank you,
Mandi

[Norm]

How do I get it to make a grid of even squares

Take a piece of paper and a pencil, draw out what you want to see and then derive the arithmetic statements to compute the values you need to do the drawing.

[camickr]

You should NOT be overriding the paint() method of a JFrame.

Custom painting is done by overriding the paintComponent(...) method of a JPanel (or JComponent) and then you add the panel to the frame. See: Lesson: Performing Custom Painting (The Java™ Tutorials > Creating a GUI With JFC/Swing) for more information and examples.

[DarrylBurke]

Moved from 'New to Java'

db