Thread: Animating Graphical Sort

I am working on an assignment called "Graphical Sort", which is basically animating sort algorithm graphically.

I just need help on animating the sorting process.

I tried using Thread, but the program hangs till the threading process is completed, then it shows the final result.

Below are the picture of how my program looks like:
SkXi8.jpg
gdD38.jpg

Below is the JPanel class I made, which I paint on:

import javax.swing.*;
import java.awt.*;
import java.util.*;
 
public class PaintPanel extends JPanel
{
    // Create an array of 34 element size
    int[] Arr = new int [34];
    // Set default X pointer to 20
    int x = 50;
    // Declare Y pointer to 660
    int y = 660;
    // Set the length of array to n variable
    int n = Arr.length;
 
 
    /*
     * main method
     * @param none
     * @return none
     */
    public PaintPanel ()
    {
        randomNums ();
        revalidate ();
        repaint (0, 150, 800, 700);
    }
 
 
    /*
     * Generates random numbers between 50 and 750 and stores it into the Arr variable
     * @param none
     * @return none
     */
    public void randomNums ()
    {
        // call randomGenerator object
        Random randomGenerator = new Random ();
        // Loop 33 times = Generates 33 random integers
        for (int i = 0 ; i <= 33 ; ++i)
        {
            // Generate random Number
            int randomInt = randomGenerator.nextInt (700);
            // Conditional statement, if any number is less than 50, then discard it and generate new number
            if (randomInt > 50)
                // Assign each random number into Arr Element
                Arr [i] = randomInt;
            else
            {
                // Regenerate Random Number
                randomInt = randomGenerator.nextInt (700);
                // Assign it again
                Arr [i] = randomInt;
            }
        }
    }
 
 
    /*
     * Bubble Sort Algorithm
     * @param none
     * @return none
     */
    public void bubble ()
    { //Pre: a is an array with values. It is of size n
        //Post: the values in a are put in ascending order
        int temp;
        //int a[] = Arr;
        for (int i = 0 ; i < n - 1 ; i++)
        {
            for (int j = 0 ; j < n - 1 - i ; j++)
            { // compare the two neighbours
                if (Arr [j + 1] < Arr [j])
                { //swap the neighbours if necessary
                    temp = Arr [j];
                    Arr [j] = Arr [j + 1];
                    Arr [j + 1] = temp;
                    repaint (0, 150, 800, 700);
                }
            }
        }
    }
 
 
    /*
     * Paints 33 rectangle Strips to the screen
     * @param Graphics g
     * @return none
     */
    public void paintComponent (Graphics g)
    {
        super.paintComponent (g);
        // Call Graphics2D Object
        Graphics2D g2 = (Graphics2D) g.create ();
        // Create Paint Object with gradient Fill
        Paint p = new GradientPaint (
                0, 0, new Color (0x44A2FF),
                getWidth (), 0, new Color (0x0CBEAE),
                true
                );
        // Set the gradient fill to the Graphics2D Object
        g2.setPaint (p);
 
        // Loop through the Array and display series of Rectangular Strips
        for (int i = 0 ; i < Arr.length ; ++i)
        {
            // Fill out the Rectangle
            g2.fillRect (x, y, Arr [i], 8);
            y = y - 15;
        }
        g2.dispose ();
    }
}

What should I use to animate the process. I also want to show which rectangular strips are being compared during the process of sorting.

Thank You