"Simple" Animation

Question

Hi everyone,
I'm trying to design (what I thought to be) a simple flashcard-type program to help students learn Japanese. Basically what it's supposed to do is read images of Japanese characters (kanji) from a folder and fill a vector up with them, then animate that image vector in a small window in the top-left corner of the student's screen as they work on their computers, thereby allowing them to absorb the material.
I THOUGHT that the hardest part of the project would be to get the vector to grab the image files automatically each time it ran, but that turned out to be pretty easy and only took up 3 lines of code. The part that I just can't get to work is the animation. I've animated stuff before in applets, but I just can't get the animation to run in this Swing Application. I can get two images to display (and I can choose which image in the array), but I can't get them to scroll through. Would someone be kind enough to look over my code and see if there's somewhere I'm going blatantly wrong? I think the thread just isn't doing what I want it to...
The code comes in two files.
KanjiFlashTwo.java (the actual work):
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
public class KanjiFlashTwo extends JPanel implements Runnable {
Image imageOne;
Image imageTwo;
int i = 0;
Image blank;
Thread thread;
public void start(){
thread = new Thread(this);
thread.start();
public void run() {
     //grab images from the images directory and load the vector with them
     File dir = new File("images/");
     String[] images = dir.list();
     //my attempt at animation
     while (Thread.currentThread() == thread) {
     imageOne = Toolkit.getDefaultToolkit().getImage(images);
     repaint();
     if(i == images.length) {
          i=0;
     else {
          i++;
     try { Thread.sleep(5000); }
     catch (InterruptedException e) { System.exit(0); };
public void paintComponent(Graphics g) {
     super.paintComponent(g);
     customDrawingMethod(g);
public void customDrawingMethod(Graphics g) {
     Graphics2D g2 = (Graphics2D) g;
     double w = (double) (getSize()).getWidth();
     double h = (double) (getSize()).getHeight();
     g2.drawImage(imageOne,0,0,this);
     g2.drawImage(imageTwo,100,0,this);
and FlashKanjiTwo.java (the window to display the actual work):
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class FlashKanjiTwo extends JFrame {
public FlashKanjiTwo() {
     KanjiFlashTwo kf = new KanjiFlashTwo();
     getContentPane().add(kf, BorderLayout.CENTER);
     setTitle("Kanji Flash!");
     setSize(new java.awt.Dimension(200,100));
     addWindowListener(new WindowAdapter() {
          public void windowClosing(WindowEvent e) {
          System.exit(0);
public static void main(String[] args) {
     (new FlashKanjiTwo()).show();
Thank you SO much for any help you can give me.
-Ben

Answer 1

wouldn't a MediaTracker be useful here?Thanks for the advice! I still can't get it to animate, though. I feel pretty useless at this so far -- I'm just learning how to program and am continually stalling. This is my attempt at re-writing it to use a MediaTracker, but it still gets me nowhere. Can you recommend a good book on animation or threads or any of the important ideas behind this thing? Thanks again for your help, and if anyone can help clear this up for me I'd be extremely grateful.
My new (but not much improved) code:
import java.awt.*;
import javax.swing.*;
import java.io.*;
public class KanjiFlash extends JPanel implements Runnable {
Image[] imageOne;
Image imageTwo;
Image blank;
File dir;
String[] images;
int i = 0;
MediaTracker tracker = null;
Thread animThread = null;
double w = (double) (getSize()).getWidth();
double h = (double) (getSize()).getHeight();
public void paintComponent(Graphics g) {
     super.paintComponent(g);
     customDrawingMethod(g);
public void customDrawingMethod(Graphics g) {
     Graphics2D g2 = (Graphics2D) g;
     getKanji();
     drawKanji(w/2.0, h/2.0, g2);
public boolean getKanji() {
     tracker = new MediaTracker(this);
     dir = new File("images/" );
     images = dir.list();
     for (i=0; i<images.length; i++) {
          imageOne[i] = Toolkit.getDefaultToolkit().getImage("images/" + images);
          tracker.addImage(imageOne[i], i);
     animThread = new Thread(this);
     animThread.start();
     imageTwo = Toolkit.getDefaultToolkit().getImage("images/save.gif");
     blank = Toolkit.getDefaultToolkit().getImage("images/blank.gif");
     return true;
public void drawKanji(double w, double h, Graphics2D g2) {
     if (tracker == null) { g2.drawString("Getting Close...",20,20); }
     else
     if (tracker.checkAll()) {
     g2.drawImage(imageOne[i++],0,0,this);
     if (i>=imageOne.length) i=0;
     else {
     g2.drawImage(imageOne[0],0,0,this);
     g2.drawImage(imageTwo,100,0,this);
public void run() {
     try { tracker.waitForAll();
     for (;;) {
     repaint();
     Thread.sleep(5000);
     catch (InterruptedException ie) {};