Java Data Structure - 如何绘制选择排序的视觉效果

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

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

public class Main extends JPanel {
  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.add(new Main());
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setVisible(true);
  }
  int[] numbers = new int[50];
  int min = 20;
  int max = 100;
  boolean shuffle = false;
  static final int ITERATION_SLEEP = 150;

  public Main() {
    loadArray();
    addMouseListener(new MouseAdapter() {
      @Override
      public void mouseClicked(MouseEvent e) {
        if (shuffle)
          loadArray();
        selectionSort(numbers);
        shuffle = true;
      }
    });
  }

  @Override
  public Dimension getPreferredSize() {
    return new Dimension(300, 100);
  }

  private void loadArray() {
    for (int i = 0; i < numbers.length; i++) {
      numbers[i] = min + (int) (Math.random() * ((max - min) + 1));
    }
  }

  public void selectionSort(final int[] x) {
    new Thread(new Runnable() {
      @Override
      public void run() {
        for (int i = 0; i < x.length - 1; i++) {
          int minIndex = i; 
          for (int j = i + 1; j < x.length; j++) {
            if (x[minIndex] > x[j]) {
              minIndex = j;
            }
          }
          if (minIndex != i) {
            int temp = x[i];
            x[i] = x[minIndex];
            x[minIndex] = temp;
          }
          repaint();
          try {
            Thread.sleep(ITERATION_SLEEP);
          } catch (InterruptedException e) {
            e.printStackTrace();
          }
        }
      }
    }).start();
  }

  private void drawPass(Graphics g) {
    int rectWidth = 1;

    int width = getWidth() - 1;
    int height = getHeight() - 1;
    int colSpan = Math.round((float) width / (float) numbers.length);
    int x = 0;

    for (int num : numbers) {
      int colHeight = (int) ((float) height * ((float) num / (float) 100));
      g.fillRect(x, height - colHeight, rectWidth, colHeight);
      x += colSpan;
    }
  }
  @Override
  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    drawPass(g);
  }
}