Painting with JPanel

Question

I have many classes, but only 3 matter. The problem is that my JPanel will not repaint. I tried using the repaint method, but it won't go to paintComponent.
My main class is:
package MainClass;
* Main.java
* Created on January 25, 2007, 5:05 PM
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
* @author Wizardus
import Graphics.*;
import Utilities.*;
import Loading.*;
import java.util.Vector;
import MainClass.*;
public class Main {
    public Frame frame;
    public MenuListener listen;
    public String currMode;
    public String tmpFileName;
    public GWInterface gwi;
    public Loader load;
    public Vector stuffs;
    /** Creates a new instance of Main */
    public Main() {
        listen = new MenuListener(this);
        frame = new Frame(this);
        frame.addKeyListener(listen);
    public void newGame() {
        gwi = new GWInterface(false, false);
        Loader load = new Loader();
        //Campaign camp = load.loadCampaign("someone");
        currMode = "GAME";
        frame.updateStage(currMode);
        //Map mp = load.loadMap(camp.mapFile);
        //stuffs = load.loadStuff(camp.stuffFile);
        Map mp = load.loadMap("someone.gwmp");
        stuffs = load.loadStuff("someone.gws");
        //AIType ai = load.loadAI(camp.aiFile);
        //gwi.ai = ai;
        gwi.idLoaded(0);
        gwi.mapLoaded(mp);
        gwi.loadUp(stuffs);
        frame.removeKeyListener(listen);
        frame.addKeyListener(gwi);
        frame.addMouseListener(gwi);
        frame.addMouseMotionListener(gwi);
        gameLoop();
    public void gameLoop() {
        while(true) {
            gwi.update();
            //gwi.ai();
            frame.updateDisp();
            System.out.println("Hi in gameLoop");
            try {
                Thread.sleep(50);
            } catch(Exception e) {
    public static void main(String[] args) {
        new Main();
}The actual JFrame is called Frame:
* Display.java
* Created on January 30, 2007, 8:44 PM
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
package Graphics;
* @author Wizardus-
import Utilities.*;
import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
import MainClass.*;
import java.util.Vector;
import Utilities.Build.*;
import Utilities.Troops.*;
public class Frame extends JFrame{
    Main mana;
    public MainPanel panel;
    /** Creates a new instance of Display */
    public Frame(Main mana) {
        super("Something something");
        this.mana = mana;
        panel = new MainPanel(mana);
        panel.loadUp();
        getContentPane().add(panel);
        setSize(1000, 700);
        setVisible(true);
    public void updateDisp() {
        System.out.println("Hi in updateB");
        panel.updateDisp();
    public void updateStage(String stage) {
        panel.updateStage(stage);
}Then, the JPanel called MainPanel is:
* Display.java
* Created on January 30, 2007, 8:44 PM
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
package Graphics;
* @author Wizardus-
import Utilities.*;
import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
import MainClass.*;
import java.util.Vector;
import Utilities.Build.*;
import Utilities.Troops.*;
public class MainPanel extends JPanel{
    String stage = "MENU";
    //BufferStrategy img;
    Main mana;
    Image backgroundDesign;
    Image panel;
    Image[] units;
    Image[] buildings;
    Image[] terrains;
    /** Creates a new instance of Display */
    public MainPanel(Main mana) {
        super();
        this.mana = mana;
        setSize(1000,700);
        setVisible(true);
    public void loadUp() {
        //createBufferStrategy(2);
        //img = getBufferStrategy();
        loadImg();
    public void loadImg() {
        //load the crap images!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! YEAH
    public void updateDisp() {
        System.out.println("Hi in updateA");
        repaint();
    public void updateStage(String stage) {
        this.stage = stage;
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        System.out.println("painting...");
        //Graphics g = img.getDrawGraphics();
//        System.out.println(stage);
        if(stage.equals("MENU")) {
//            //draw menu and menu's buttons
        } else if(stage.equals("GAME")) {
//            //draw EVERYTHING in game
//            //Step 0 draw map and background for panels
//            g.drawImage(panel, 700, 0, null);
//            g.drawImage(backgroundDesign, 690, 0, null);
//            Map mp = mana.gwi.offmap;
//            for(int i = 0; i < mp.terrain.length; i++) {
//                for(int j = 0; j < mp.terrain.length; j++) {
// Terrain curr = mp.terrain[i][j];
// g.drawImage(terrains[curr.nameId], (mp.terrain.length * 15) + mana.gwi.mapX, (mp.terrain[i].length * 15) + mana.gwi.mapY, null);
// //Step 1 draw buttons;
// for(int i = 0; i < mana.gwi.defButtons.length; i++) {
// g.drawRect(mana.gwi.defButtons[i].x, mana.gwi.defButtons[i].y, mana.gwi.defButtons[i].width, mana.gwi.defButtons[i].height);
// g.drawString(mana.gwi.defButtons[i].txt, mana.gwi.defButtons[i].x, mana.gwi.defButtons[i].y);
// for(int i = 0; i < mana.gwi.currButtons.length; i++) {
// g.drawRect(mana.gwi.currButtons[i].x, mana.gwi.currButtons[i].y, mana.gwi.currButtons[i].width, mana.gwi.currButtons[i].height);
// g.drawString(mana.gwi.currButtons[i].txt, mana.gwi.currButtons[i].x, mana.gwi.currButtons[i].y);
//Step 2 draw units of each "Stuff" and the buildings;
for(int i = 0; i < mana.gwi.stuff.size(); i++) {
Stuff currStuff = (Stuff)mana.gwi.stuff.get(i);
// for(int j = 0; j < currStuff.buildings.size(); j++) {
// Buildings currBuild = (Buildings)currStuff.buildings.get(j);
// g.drawImage(buildings[currBuild.nameId], (int)currBuild.x, (int)currBuild.y, null);
for(int j = 0; j < currStuff.troops.size(); j++) {
Soldier currSold = (Soldier)currStuff.troops.get(j);
//g.drawImage(units[currSold.nameId], (int)currSold.x, (int)currSold.y, null);
g.drawRect((int)(currSold.x), (int)(currSold.y), 20,20);
//img.show();

Answer 1

Thats because in your gameLoop you use Thread.sleep(...) which causes the GUI Thread to sleep. If the thread is sleeping then it never gets a chance to repaint itself.
If you want you game to repaint itself then use a [url http://java.sun.com/docs/books/tutorial/uiswing/misc/timer.html]Swing Timer to schedule the repainting and get rid of the Thread.sleep(..).