[hardwired]

Code:

import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.swing.*;

public class RandomImagesTest2 {
    BufferedImage[] images;
    Random seed = new Random();
    JLabel left;
    JLabel right;

    RandomImagesTest2() {
        makeImages();
        new Thread(runner).start();
    }

    private Runnable runner = new Runnable() {
        long delay = 1000;
        boolean animate = true;
        boolean firstTime = true;

        public void run() {
            while(animate) {
                try {
                    Thread.sleep(delay);
                } catch(InterruptedException e) {
                    animate = false;
                }
                left.setIcon(getIcon());
                right.setIcon(getIcon());
                if(firstTime && left.isVisible()) {
                    Rectangle rL = left.getBounds();
                    Rectangle rR = right.getBounds();
                    System.out.printf("leftBounds = [%d, %d, %d, %d]  " +
                                      "rightBounds = [%d, %d, %d, %d]%n",
                                       rL.x, rL.y, rL.width, rL.height,
                                       rR.x, rR.y, rR.width, rR.height);
                    firstTime = false;
                }
                left.repaint();
                right.repaint();
            }
        }
    };

    private void makeImages() {
        int alpha = 140;
        Color[] colors = {
            new Color(255, 0, 0, alpha), new Color(0, 0, 255, alpha)
        };
        int w = 90, h = 50;
        int type = BufferedImage.TYPE_INT_ARGB;
        images = new BufferedImage[colors.length];
        for(int i = 0; i < images.length; i++) {
            images[i] = new BufferedImage(w, h, type);
            Graphics2D g2 = images[i].createGraphics();
            g2.setBackground(colors[i]);
            g2.clearRect(0,0,w,h);
            g2.dispose();
        }
    }

    private JPanel getContent() {
        left  = new JLabel(getIcon(), JLabel.CENTER);
        right = new JLabel(getIcon(), JLabel.CENTER);
        JPanel panel = new JPanel(null);
        panel.add(left);
        panel.add(right);
        left.setBounds(50,50,90,50);
        right.setBounds(100,50,90,50);
        return panel;
    }

    private ImageIcon getIcon() {
        int n = seed.nextInt(images.length);
        return new ImageIcon(images[n]);
    }

    public static void main(String[] args) {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new RandomImagesTest2().getContent());
        f.setSize(300,300);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}