JOptionPane keeps on overlapping values on JFrame

Question

I'm new to JFrame, and I wanted to know why my JOptionPane won't stop popping up. When I type into the JOptionPane continuously, the values keep overlapping on the JFrame overtop of the previous ones, and it's keeping my program in a loop, preventing the printing process from opening up. I think it's because the program requests input values in a public void class rather than a public static void main class, but I don't know how to put these values on a JFrame otherwise because of the graphics component.

import java.awt.*;
import java.awt.print.PageFormat;
import java.awt.print.PrinterException;
import java.awt.print.PrinterJob;

import javax.swing.*;
public class Assignment3 extends JFrame
{
Assignment3()
{
    setTitle("Amber's Skateboarders");
    setSize(1200,720);
    setVisible(true);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public void paint(Graphics g)
{   
    Font bigName = new Font("Ariel Bold", Font.BOLD, 20);
    Font company = new Font("Comic Sans", Font.BOLD, 12);
    Font myList = new Font("Comic Sans", Font.PLAIN, 12);

    g.setFont(bigName);
    g.drawString("Skateboarders", 15, 100);
    String companyName;
    String companyAddress;
    int itemIndex = 0;
    int pricesIndex = 0;
    int quantityIndex = 0;
    String[] merchandise = new String[1000];
    double[] prices = new double[1000];
    int[] quantity = new int[1000];
    int addMore;
    String[] options = {"Yes", "No"};
    double subtotal = 0;
    double[] result = new double[1000];
    String[] list = new String[1000];

    companyName = JOptionPane.showInputDialog(null, "What is your company name?");
    g.setFont(company);
    g.drawString(companyName, 15, 115);
    companyAddress = JOptionPane.showInputDialog(null, "What is your company's address?");
    g.setFont(company);
    g.drawString(companyAddress, 15, 130);

    do
    {
        merchandise[itemIndex] = JOptionPane.showInputDialog(null, "What is the name of the item you want?");
        prices[pricesIndex] = Double.parseDouble(JOptionPane.showInputDialog(null, "How much does this cost?"));
        quantity[quantityIndex] = Integer.parseInt(JOptionPane.showInputDialog(null, "How much of this item do you need?"));
        itemIndex++;
        pricesIndex++;
        quantityIndex++;
        addMore = JOptionPane.showOptionDialog(null, "Do you want to add more to your shopping cart?", "Before you go!", JOptionPane.DEFAULT_OPTION, JOptionPane.WARNING_MESSAGE,null, options, options[0]);
    }
    while(addMore == 0);
    int k;
    g.setFont(myList);
    if (addMore == 1)
    {   
        for (int i = 0; i <= pricesIndex-1; i++)
        {
            result[i] = prices[i]*quantity[i];
        }
        for (double j : result)
        {
            subtotal += j;
        }       
        for (k = 0; k<pricesIndex; k++)
        {
            list[k] = String.valueOf(quantity[k])+"\u00D7"+merchandise[k];
            g.drawString(list[k], 15, k*15+145);
            g.drawString("$" +String.valueOf(result[k]), 120, k*15+145);
            //all += String.valueOf(quantity[k])+"\u00D7"+merchandise[k]+"\t\t\t"+String.valueOf(result[k])+"\n";
        }
        k=pricesIndex;
        double taxes = subtotal*0.2;
        g.setFont(company);
        g.drawString("Subtotal: ", 15, k*15+145);
        g.drawString("$"+String.valueOf(subtotal), 120, k*15+145);
        k++;
        g.drawString("Tax: ", 15, k*15+145);
        g.drawString("$"+String.valueOf(taxes), 120, k*15+145);
        k++;
        g.drawString("Total: $", 15, k*15+145);
        g.drawString("$"+String.valueOf(taxes+subtotal), 120, k*15+145);
}
public static void main(String[] args)
{
    Assignment3 main = new Assignment3();
    main.paint(null);
}
}

Answer 1

I think your problem in next:

1) You invoke your JOptionPane inside paint() method, it is'n proper way.

2) Why you draw your items with Graphics, I think you can use JLabel's or JTextField's as recommended by @trashgod. I recommend you to use JTable, i think it is suitable for your case. read tutorial for that.

3) You can add new items with help of button action(tutorial for button) instead of while looping.

4) If you want actually to draw your data on component. Extend JPanel class, add instance of it to your JFrame and paint in paintComponents(Graphics g) method.