Dynamically changing the size of a JPanel

Question

Hi All,
I am loading multiple images in a JPanel. I want the size of the JPanel to increase dynamically as and when the images are loaded. I have also added a JScrollPane and added the JPanel to this JScrollPane.
However, the images are cut as soon as it crosses 800 pixels (which is the preferred size of the JScrollPane and it starts to give me NullPointerExceptions where I try to access the image height and width. Here is the code that gives me the problem. The files are opened using the filechooser and put into a Vector, which is then retrieved in the paint() method and rendered to the panel.
CurrentScreenSize is a Dimension that stores the value of the current screent size that the image pane should have.
imagePane is the JPanel that contains all the images.
//File | Open action performed
void jMenuFileOpen_actionPerformed(ActionEvent e) {
//Handle open action.
if (e.getSource() == jMenuFileOpen) {
fc = new JFileChooser();
//Filter out only image files (uses Utils.java and ImageFilter.java)
fc.addChoosableFileFilter(new ImageFilter());
fc.setAcceptAllFileFilterUsed(false);
fc.setMultiSelectionEnabled(true);
int returnVal = fc.showOpenDialog(MainFrame.this);
if (returnVal == JFileChooser.APPROVE_OPTION) {
File[] files = fc.getSelectedFiles();
//This is where a real application would open the file.
int x=10, y=50;
for(int i=0;i<files.length;i++)
try {
Image tempImage = ImageIO.read(files);
image.add(tempImage);
if(tempImage.getHeight(this) > currentScreenSize.getHeight())
currentScreenSize.setSize(currentScreenSize.getWidth()
+ tempImage.getWidth(this),
tempImage.getHeight(this));
else
currentScreenSize.setSize(currentScreenSize.getWidth()
+ tempImage.getWidth(this),
currentScreenSize.getHeight());
if (imagePane.getSize().getWidth() <
currentScreenSize.getSize().getWidth() ||
imagePane.getSize().getHeight() <
currentScreenSize.getSize().getHeight())
imagePane.setSize(currentScreenSize);
this.pack();
//repaint();
catch (IOException ex) {
ex.printStackTrace();
//When all images are loaded then paint it / display it
repaint();
public void paint(Graphics g){
int x=10, y=50;
super.paint(g);
g = imagePane.getGraphics();
for (int j=0; j<image.size() ; j++)
Image img = (Image)image.elementAt(j);
int imageWidth = img.getWidth(this);
int imageHeight = img.getHeight(this);
g.drawImage(img, x, y, imageWidth, imageHeight, this);
x = x+imageWidth;

Answer 1

got the Solution, using validate() method does the work under the hood.