Thread: anti doublebuffer or lag?

So far on my demo you can walk around (no collision detection yet) and type a message. When I was walking around I noticed a problem. Every once in a while the character sprite will lag/jump, and im not sure if this is due to the fact that I don't double buffer, or my code is laggy. Here is all of my code.


gameMain.class

import javax.swing.JFrame;
 
 
public class gameMain {
	public static void main(String[] args){
		chatBox chatBox = new chatBox();
		keyBoard kb = new keyBoard();
		gui gui = new gui();
 
 
		JFrame f = new JFrame("BrettScape");
		f.setSize(646,500);
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		f.setResizable(false);
 
		f.add(gui);
		f.addKeyListener(kb);
		f.setFocusTraversalKeysEnabled(false);
		f.setVisible(true);
 
 
		while(true) {
			gui.updateScreen(chatBox.getMessages(), kb.getMessage(), kb.getX(), kb.getY());
		}
	}	
}

chatBox.class

 
public  class chatBox {
	String messageBox[]={"Welcome to BrettScape!","","","",""};
 
	public String[] getMessages(){
		return messageBox;
	}
	public void addMessage(String newMess){
		messageBox[4] = messageBox[3];
		messageBox[3] = messageBox[2];
		messageBox[2] = messageBox[1];
		messageBox[1] = messageBox[0];
		messageBox[0] = newMess;
	}
}

gui.class

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
 
import javax.imageio.ImageIO;
import javax.swing.*;
 
public class gui extends JPanel {
	BufferedImage img,chatBoxImg,avatar;
	String messages[];
	String typing;
	int map[][]={ //I know this map is in my gui class, but I'm going to add a different class for maps.
			{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
			{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
			{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
			{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
			{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
			{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
			{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
			{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
			{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
			{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
			{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
			{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
	};
	int messCount,row,column,playerX,playerY;
 
	public gui(){
		try {
			img = ImageIO.read(new File("tiles.png"));
			chatBoxImg = ImageIO.read(new File("chat.png"));
			avatar = ImageIO.read(new File("avatar.png"));
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
 
	public void updateScreen(String[] messages, String typing, int playerX, int playerY){
		this.messages = messages;
		this.typing = typing;
		this.playerX = playerX;
		this.playerY = playerY;
		repaint();
	}
 
	public void paintComponent(Graphics g){		
		//draw first tile layer
		for(column=0;column<=11;column++) {
			for(row=0;row<=19;row++){
				g.drawImage(img, row*32, column*32, row*32+32, column*32+32, map[column][row]*32, 0, map[column][row]*32+32, 32, null);
			}
		}	
 
		//second layer
		g.drawImage(avatar, playerX, playerY, null);
 
		//third layer
 
		//draws messages for chat box
		g.drawImage(chatBoxImg, 0, 384, null);
		for(messCount=0;messCount<=4;messCount++){
			g.drawString(messages[messCount], 5, 400+(messCount*14));
		}	
 
		//draw what the person is typing
		g.drawString(typing+"*", 5, 468);
	}
}

keyBoard.class

import java.awt.event.*;
 
public class keyBoard implements KeyListener {
	int keyCode;
	int playerX,playerY=10;
	String message="";
 
 
	public int getX(){
		return playerX;
	}
 
	public int getY(){
		return playerY;
	}
 
	public String getMessage(){
		return message;
	}
 
	public void keyPressed(KeyEvent e){
		keyCode = e.getKeyCode();
 
		if (keyCode == KeyEvent.VK_LEFT) {
			playerX-=5;
		}
		if (keyCode == KeyEvent.VK_RIGHT) {
			playerX+=5;
		}
		if (keyCode == KeyEvent.VK_UP) {
			playerY-=5;
		}
		if (keyCode == KeyEvent.VK_DOWN) {
			playerY+=5;
		}
		//Detection of normal keys
		if ("ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#$%^&*(),PeriodComma/?;:`~[]{}=+<>Space".indexOf(KeyEvent.getKeyText(keyCode)) >= 0) {
			message+=KeyEvent.getKeyText(keyCode).replace("Space", " ").replace("Period", ".").replace("Comma", ",").toLowerCase();
 
			//capitalize the first letter
			if (message.length() == 1) 
				message = message.toUpperCase();
		}
 
		//if backspace delete last letter
		if (KeyEvent.getKeyText(keyCode) == "Backspace") {
			if(message.length() >= 1)
				message = message.substring(0, message.length()-1);
		}
 
 
 
 
	}
 
 
	public void keyReleased(KeyEvent e){
 
	}
 
	public void keyTyped(KeyEvent e){
 
	}
}

Swing components are by default double buffered, so this might not be the issue. You may wish to profile your code by printing out a bunch of times for certain routines...there are a few areas that can be optimized (for example the tiling could be written once to a BufferedImage, and then rather than loop to draw each tile each time in the paintComponent, you could just draw that the tiling composite image once).

What I would recommend is having the camera follow the character around, but still have the character moving through the map.

So how would I go about doing that?