Update picture in JPanel

Question

i'm have a picture, i showed it in JPanel, but my picture is change at any time, how i can update new picture on JPanel when my picture is updated
//add picture in JPanel
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import javax.swing.JPanel;
class ImagePanel extends JPanel {
    private Image img;
    public ImagePanel(Image img) {
        this.img = img;
        Dimension size = new Dimension(img.getWidth(null), img.getHeight(null));
        setPreferredSize(size);
        setMinimumSize(size);
        setMaximumSize(size);
        setSize(size);
        setLayout(null);
    public void paintComponent(Graphics g) {
        g.drawImage(img, 0, 0, null);
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.rmi.Naming;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
public class ShowClient extends JFrame implements MouseMotionListener{
    public ShowClient() {
        super("Control Client");
        UpdatePicture();
    //this method
    public void UpdatePicture(){
        ImagePanel panel =
                new ImagePanel(new ImageIcon("screen.jpg").getImage());
        JScrollPane scrollPane = new JScrollPane(panel);
        this.setLayout(new BorderLayout());
        this.add(scrollPane, BorderLayout.CENTER);
        scrollPane.addMouseMotionListener(this);
          when mouser move will have a new picture.
    public void mouseMoved(MouseEvent e){
        int x = e.getX();
        int y = e.getY();
        EventServer event = null;
        try {
            event = (EventServer)Naming.lookup("//localhost/Client");
            event.MouseMove(x, y);
        catch (Exception exp){
            System.out.println("Err " + exp);
        UpdatePicture(); //why here my JPanel don't show new picture
    public void mouseDragged(MouseEvent e){
    public void Show(){
        this.setDefaultCloseOperation(HIDE_ON_CLOSE);
        Toolkit tool = Toolkit.getDefaultToolkit();
        Dimension size = tool.getScreenSize();
        this.setSize(size);
        this.setVisible(true);
}Thank a lot of !!
Edited by: bathong on May 23, 2009 10:39 AM

Answer 1

>
If you mean that the image file is updated, you will need to either reload the Image from the file using ImageIO#read(...) or flush() the Image.
When you load the image using the ImageIcon constructor that takes a String parameter, it is cached by Toolkitand will not be reloaded even if the file content changes.
Why create an ImageIcon just to retrieve its Image? Use ImageIO and just load an Image.
db
>
I rewrite as :
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import javax.swing.JPanel;
class ImagePanel extends JPanel {
    public BufferedImage img;
    public ImagePanel(BufferedImage img) {
        this.img = img;
        Dimension size = new Dimension(img.getWidth(null), img.getHeight(null));
        setPreferredSize(size);
        setMinimumSize(size);
        setMaximumSize(size);
        setSize(size);
        setLayout(null); 
    public void paintComponent(Graphics g) {
        g.drawImage( img, 0, 0, null);
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.rmi.Naming;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
public class ShowClient extends JFrame implements MouseMotionListener{  
    public ShowClient() {
        super("Control Client");
        UpdatePicture();
    public void UpdatePicture(){
        try { 
            File file = new File("screen.jpg");
            BufferedImage buff = ImageIO.read(file);
            ImagePanel panel = new ImagePanel(buff);
            JScrollPane scrollPane = new JScrollPane(panel);
            this.setLayout(new BorderLayout());
            this.add(scrollPane, BorderLayout.CENTER);
            scrollPane.addMouseMotionListener(this); 
        catch (Exception exp){
            System.out.println("Error here " + exp);
            exp.printStackTrace();
    public void mouseMoved(MouseEvent e){
        int x = e.getX();
        int y = e.getY();
        EventServer event = null;
        try {
            event = (EventServer)Naming.lookup("//localhost/Client");
            event.MouseMove(x, y);
        catch (Exception exp){
            System.out.println("Err " + exp);
        UpdatePicture();
    public void mouseDragged(MouseEvent e){
    public void Show(){
        this.setDefaultCloseOperation(HIDE_ON_CLOSE);
        Toolkit tool = Toolkit.getDefaultToolkit();
        Dimension size = tool.getScreenSize();
        this.setSize(size);
        this.setVisible(true);
}but new picture also can't update!! please help me, thank !!!!