Develop Reference

How to draw a circle in JPanel 2D

Hello I am new to JAVA and recently studied graphics but got stuck on how to draw a circle (I learn on my own through Google) I would be happy if you help me with the following lines of code
(Do not refer to the background sub button)
public class Panel_ {
static JPanel panel1 = new JPanel();
public static Color randomColor() {
int r = (int) Math.round(Math.random() * 255 - 1);
int g = (int) Math.round(Math.random() * 255 - 1);
int b = (int) Math.round(Math.random() * 255 - 1);
Color R_col = new Color(r, g, b);
System.out.println(R_col);
return R_col;
}
public static void Panel() {
var color_changer = new JButton("To change color");
color_changer.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
panel1.setBackground(randomColor());
}
});
var Panel = new JPanel();
Panel.add(color_changer);
Panel.setBackground(Color.blue);
panel1.setBackground(Color.black);
panel1.setPreferredSize(new Dimension(400, 430));
var frame = new JFrame("Color changer");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(panel1, BorderLayout.NORTH);
frame.getContentPane().add(Panel, BorderLayout.SOUTH);
frame.pack();
frame.setSize(500, 500);
frame.setBackground(Color.blue);
frame.setVisible(true);
}
public void paintCircle(Graphics g) {
g.setColor(Color.blue);
g.fillOval(60, 80, 100, 100);
}
public static void main(String args[]) {
Panel();
}
}

Use paintComponent for panel1 which I changed the name to topPanel in the runnable code below:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import javax.swing.*;
public class Panel extends JFrame {
private static final long serialVersionUID = 1L;
private JPanel topPanel;
private JPanel panel;
private JButton color_changer;
public Panel() {
initializeForm();
}
private void initializeForm() {
setAlwaysOnTop(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBackground(Color.blue);
color_changer = new JButton("To change color");
color_changer.addActionListener((ActionEvent e) -> {
topPanel.setBackground(randomColor());
});
topPanel = new JPanel() {
private static final long serialVersionUID = 1L;
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.blue);
g.fillOval(60, 80, 100, 100);
};
};
panel = new JPanel();
panel.add(color_changer);
panel.setBackground(Color.blue);
topPanel.setBackground(Color.black);
topPanel.setOpaque(true);
topPanel.setPreferredSize(new Dimension(400, 430));
getContentPane().add(topPanel, BorderLayout.NORTH);
getContentPane().add(panel, BorderLayout.SOUTH);
pack();
setLocationRelativeTo(null);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(() -> {
new Panel().setVisible(true);
});
}
public static Color randomColor() {
int r = (int) Math.round(Math.random() * 255 - 1);
int g = (int) Math.round(Math.random() * 255 - 1);
int b = (int) Math.round(Math.random() * 255 - 1);
Color R_col = new Color(r, g, b);
System.out.println(R_col);
return R_col;
}
}

Why can I not move the array initializer?

Whenever I try to move the array lifegrid, the complier gives errors and something goes wrong with the window. Not sure what the array has to do with that as I am not yet using it to change the displayed information.
I want to be able to call my code in the class LifeRunningCode but because my array is defined in MyPanel it is not visible in CreateAndShowGUI. I need it to be visible to both methods. Can I place it just before the MAIN method?
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class SwingPaintDemo3 {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
static void createAndShowGUI() {
System.out.println("Created GUI on EDT? " + SwingUtilities.isEventDispatchThread());
JFrame f = new JFrame("Swing Paint Demo");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new MyPanel());
f.pack();
JPanel subPanel = new JPanel();
JButton seed = new JButton("SEED");
subPanel.add(seed);
seed.setPreferredSize(new Dimension(70, 50));
seed.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
System.out.println("Seed");
}
});
JButton start = new JButton("START");
subPanel.add(start);
start.setPreferredSize(new Dimension(70, 50));
start.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae1) {
System.out.println("Start");
//lifegrid = LifeRunningCode.changeValues(lifegrid);
}
});
start.setPreferredSize(new Dimension(70, 50));
JButton stop = new JButton("STOP");
subPanel.add(stop);
stop.setPreferredSize(new Dimension(70, 50));
JButton reset = new JButton("RESET");
subPanel.add(reset);
reset.setPreferredSize(new Dimension(70, 50));
f.add(subPanel, BorderLayout.EAST);
f.setVisible(true);
}
}
class MyPanel extends JPanel {
int lifegrid[][][] = new int[62][42][2];
int squareX = 1280;
int squareY = 800;
int gridX = 0;
int gridY = 0;
public MyPanel() {
addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
squareX = e.getX();
squareY = e.getY();
if ((squareX > 20 & squareX < 920) & (squareY > 50 & squareY < 650)) {
gridX = (squareX - 20) / 15 + 1;
gridY = (squareY - 50) / 15 + 1;
squareX = (squareX - 20) / 15 * 15 + 20;
squareY = (squareY - 50) / 15 * 15 + 50;
lifegrid[gridX][gridY][0] = 1;
System.out.println(gridX + " " + gridY);
repaint(squareX, squareY, 15, 15);
}
else {}
}
});
}
public Dimension getPreferredSize() {
return new Dimension(1280, 800);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.RED);
g.fillRect(squareX, squareY, 13, 13);
g.setColor(Color.BLACK);
g.drawRect(squareX, squareY, 13, 13);
}
}

All the UI objects are localized in createAndShowGUI method.
If you need to access the array inside an instance of MyPanel class you should:
create a getter for this array in MyPanel
store an instance of MyPanel inside main class SwingPaintDemo3 and refer it as necessary:
// MyPanel
class MyPanel extends JPanel {
// ...
public int[][][] getLifegrid() {
return lifegrid;
}
}
// SwingPaintDemo3
public class SwingPaintDemo3 {
static MyPanel myPanel = new MyPanel();
static void createAndShowGUI() {
System.out.println("Created GUI on EDT? " + SwingUtilities.isEventDispatchThread());
JFrame f = new JFrame("Swing Paint Demo");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(myPanel);
// ...
start.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae1) {
System.out.println("Start");
LifeRunningCode.changeValues(myPanel.getLifegrid());
}
});
// ...
}
}

Having troubles rendering rectangle on button press

I am trying to add a Rectangle in the panel by button press and remove it with another one. It should work but it doesn't render anything, and I absolutely don't know why.
Can someone explain what I am doing wrong and give me some nice tips what I can improve with my code?
public class GUI extends JPanel {
public static boolean isRecVisible = false;
public static void main(String[] args) {
createGui();
}
#Override
protected void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
super.paintComponent(g);
g2d.drawRect(10, 10, 200, 200);
}
public static void createGui() {
int frameWidth = 550;
int frameHeight = 400;
int buttonWidth1 = 250;
int buttonHeight1 = 30;
int buttonWidth2 = 500;
int buttonHeight2 = 30;
int displayWidth = frameWidth - 20;
int displayHeight = frameHeight - 105;
GUI drawRec = new GUI();
JFrame f = new JFrame("Rectangle");
JPanel p = new JPanel();
JPanel display = new JPanel();
JButton addRec = new JButton("Add Rectangle");
JButton removeRec = new JButton("Remove Rectangle");
JButton colorRec = new JButton("Color Rectangle");
f.add(p);
p.add(addRec);
p.add(removeRec);
p.add(colorRec);
p.add(display);
display.setBackground(Color.LIGHT_GRAY);
f.setSize(frameWidth, frameHeight);
f.setLocationRelativeTo(null);
f.setResizable(false);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
display.setBounds(frameWidth / 2 - displayWidth / 2, 10, displayWidth, displayHeight);
addRec.setBounds(frameWidth / 2 - buttonWidth1 / 2 - 250 / 2, frameHeight - 85, buttonWidth1, buttonHeight1);
removeRec.setBounds(frameWidth / 2 - buttonWidth1 / 2 + 250 / 2, frameHeight - 85, buttonWidth1, buttonHeight1);
colorRec.setBounds(frameWidth / 2 - buttonWidth2 / 2, frameHeight - 60, buttonWidth2, buttonHeight2);
addRec.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (isRecVisible == false) {
isRecVisible = true;
display.add(drawRec);
display.repaint();
System.out.println("Rectangle has been drawn!");
} else {
System.out.println("Rectangle has already been drawn!");
return;
}
}
});
removeRec.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (isRecVisible == true) {
isRecVisible = false;
System.out.println("Rectangle has been removed!");
} else {
System.out.println("Rectangle has already been removed");
return;
}
}
});
}
}

display.add(drawRec);
display.repaint();
When you add (or remove) components to a visible frame then the basic logic is:
display.add(...);
display.revalidate();
display.repaint(); // sometimes needed
The revalidate() is the key method because it invokes the layout manager so the size/location of the component can be set.
However, that still won't fix the problem because your custom panel doesn't have a preferred size, so there is nothing to paint for your component.
You need to override the getPreferredSize() method of your custom panel to return the preferred size of your custom component. So in your case you might set the preferred size to be (220, 220) so the rectangle is centered in the panel.
Read the section from the Swing tutorial on Custom Painting for more information and complete working examples.
Note: the tutorial example will also show you how to better structure your code to make sure the GUI is created on the Event Dispatch Thread.

Rather than adding or removing components, it would make more sense here to add the custom painted panel on construction, and use the isRecVisible boolean as a flag to test for drawing the rectangle.
Something like shown here:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GUI extends JPanel {
public static boolean isRecVisible = false;
public static void main(String[] args) {
createGui();
}
#Override
protected void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
super.paintComponent(g);
if (isRecVisible) {
g2d.drawRect(10, 10, 200, 200);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(600,400);
}
public static void createGui() {
int frameWidth = 550;
int frameHeight = 400;
GUI drawRec = new GUI();
drawRec.setBackground(Color.LIGHT_GRAY);
JFrame f = new JFrame("Rectangle");
JPanel p = new JPanel();
JButton addRec = new JButton("Add Rectangle");
JButton removeRec = new JButton("Remove Rectangle");
JButton colorRec = new JButton("Color Rectangle");
f.add(p, BorderLayout.PAGE_START);
p.add(addRec);
p.add(removeRec);
p.add(colorRec);
f.add(drawRec);
f.setSize(frameWidth, frameHeight);
f.setLocationRelativeTo(null);
f.setResizable(false);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
addRec.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
isRecVisible = true;
drawRec.repaint();
}
});
removeRec.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
isRecVisible = false;
drawRec.repaint();
}
});
}
}

JPanel does not appear after click JButton

My JPanel doesn't show up when my JButton is clicked. It does shows up when I add the JPanel in my go() method. However, once I tried to execute it by click the JButton, it doesn't work. The program does goes into the loop of the actionPeformed() method of the listener though.
public class MyShape
{
JFrame frame;
JPanel panel;
JButton drawButton;
public static void main (String[] args)
{
MyShape test = new MyRandomShape();
test.go();
}
public void go()
{
drawButton = new JButton("Draw Shape!");
drawButton.addActionListener(new DrawListener());
frame = new JFrame();
frame.add(drawButton, BorderLayout.NORTH);
frame.setSize(500,500);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private class DrawListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
if(empty)
{
System.out.print("IN");
panel = new DrawPanel();
frame.add(panel, BorderLayout.CENTER);
}
}
}
private class DrawPanel extends JPanel
{
public void paintComponent(Graphics g)
{
super.paintComponents(g);
int randNo = (int)(Math.random() * 3);
int width = (int)(Math.random() * getWidth());
int height = (int)(Math.random() * getHeight());
int xpos = getWidth()/2-width/2;
int ypos = getHeight()/2-height/2;
int v1 = (int)(Math.random() * 256);
int v2 = (int)(Math.random() * 256);
int v3 = (int)(Math.random() * 256);
g.setColor(new Color(v1, v2, v3));
if(randNo == 0)
{
g.fillOval(xpos, ypos, width, height);
}
else if(randNo == 1)
{
g.fillRect(xpos, ypos, width, height);
}
else
{
int startAngle = (int)(Math.random() * 360);
int arcAngle = (int)(Math.random() * 360);
g.fillArc(xpos, ypos, width, height, startAngle, arcAngle);
}
}
}
}
How do I get the JPanel to show up once the button is clicked?

You have to call parentComponent.revalidate() every time you do one or more parentComponent.add(childComponent) (or change its children in other ways, such as reorder or remove them).
In your case, your code should be
private class DrawListener implements ActionListener {
public void actionPerformed(ActionEvent event)
{
if(empty)
{
System.out.print("IN");
panel = new DrawPanel();
frame.add(panel, BorderLayout.CENTER);
frame.revalidate(); // <---------- important
}
}
}

Few changes, check this
public static void main(String[] args) {
MyShape test = new MyShape();
test.go();
}
public void go() {
drawButton = new JButton("Draw Shape!");
drawButton.addActionListener(new DrawListener());
frame = new JFrame();
frame.getContentPane().add(drawButton, BorderLayout.NORTH);
panel = new DrawPanel();
frame.getContentPane().add(panel, BorderLayout.CENTER);
frame.setSize(500, 500);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private class DrawListener implements ActionListener {
public void actionPerformed(ActionEvent event) {
frame.getContentPane().remove(1);
panel = new DrawPanel();
frame.getContentPane().add(panel, BorderLayout.CENTER);
frame.repaint();
frame.validate();
}
}

HEAPSPACE ERROR: cannot figure out what is causing the error

Would anyone mind having a look at these bits of code and see if there is a memory leak in them, it isn't going to be overly large but my program keeps crashing after a while of running and I don't know how to use viualvm even though I have been reading up on it for several days now and haven't the slightest idea what I am looking for in the heap dumps and so on. thanks for your help,
ps I know I have posted far to muchg code but i dont know what else to do so that you can hopefully see where the problem arises for me. If it helps I can email you the full program to take a look at. Thanks very much for any help you can give.
public class extraScreenPanel {
static JPanel screenPanel = new JPanel(new BorderLayout());
public static JPanel extraScreenPanel(int dispNum)
{
JLabel label = new JLabel("" + dispNum + "");
label.setPreferredSize(new Dimension(800, 600));
label.setVerticalAlignment( SwingConstants.TOP );
screenPanel = imgDisp(dispNum);
label.setForeground(Color.white);
label.setFont(new Font("Serif", Font.BOLD, 200));
screenPanel.add(label, BorderLayout.PAGE_END );
return screenPanel;
}
public static JPanel imgDisp(int picNum) {
String ref = "C:/PiPhotoPic/pic16.jpg";;
BufferedImage loadImg = loadImage(ref);
JImagePanel panel = new JImagePanel(loadImg, 0, 0);
panel.setPreferredSize(new Dimension(800, 600));
return panel;
}
public static class JImagePanel extends JPanel{
private BufferedImage image;
int x, y;
public JImagePanel(BufferedImage image, int x, int y) {
super();
this.image = image;
this.x = x;
this.y = y;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, x, y, null);
}
}
public static BufferedImage loadImage(String ref) {
BufferedImage bimg = null;
try {
bimg = javax.imageio.ImageIO.read(new File(ref));
} catch (Exception e) {
e.printStackTrace();
}
BufferedImage bimg2 = resize(bimg,800,600);//set these to the resolution of extra screens
return bimg2;
}
public static BufferedImage resize(BufferedImage img, int newW, int newH) {
int w = img.getWidth();
int h = img.getHeight();
BufferedImage dimg = dimg = new BufferedImage(newW, newH, img.getType());
Graphics2D g = dimg.createGraphics();
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.drawImage(img, 0, 0, newW, newH, 0, 0, w, h, null);
g.dispose();
return dimg;
}
}
Another part of the method
public class piPhoto
{
static int mostRecent = 0;
static int dispNum = 0;
static int lastDisp = 0;
static JPanel picPanel = imgDisp.imgDisp(dispNum);
static JFrame frame = new JFrame("Pi Photography");
static JPanel cornerPanel = new JPanel();
static JPanel bottomPanel = new JPanel();
static JPanel menuPanel = new JPanel(new BorderLayout());
static JPanel currentNumPanel = currentNumDisp.currentNumDisp(dispNum);
static JPanel printPanel = printOptions.printOptions();
static JPanel buttonPanel = updateButtonPanel.updateButtonPanel(mostRecent);
static JPanel screen1Panel = new JPanel();
static JPanel screen2Panel = new JPanel();
static JPanel screen3Panel = new JPanel();
static JPanel screen4Panel = new JPanel();
static JPanel screenPanel12 = new JPanel(new BorderLayout());
static JPanel screenPanel123 = new JPanel(new BorderLayout());
static JPanel screenPanel1234 = new JPanel(new BorderLayout());
static JPanel screensPanel = new JPanel(new BorderLayout());
static JPanel deskScreen = new JPanel();
static JPanel wholePanel = new JPanel(new BorderLayout());
static JPanel wholePanel2 = new JPanel(new BorderLayout());
public static void launchPiPhoto()
{
launchNC4.launch();
bottomPanel.setPreferredSize(new Dimension(1440, 200));
buttonPanel.setPreferredSize(new Dimension(1120, 200));
cornerPanel.setPreferredSize(new Dimension(300,200));
screen1Panel.setPreferredSize(new Dimension(800,600));
screen2Panel.setPreferredSize(new Dimension(800,600));
screen3Panel.setPreferredSize(new Dimension(800,600));
screen4Panel.setPreferredSize(new Dimension(800,600));
screensPanel.setPreferredSize(new Dimension(3200,600));
deskScreen.setPreferredSize(new Dimension(800,600));
wholePanel.setPreferredSize(new Dimension(4640,900));
wholePanel2.setPreferredSize(new Dimension(5440,900));
cornerPanel.setLayout(new BoxLayout(cornerPanel, BoxLayout.PAGE_AXIS));
picPanel.setPreferredSize(new Dimension(1120, 620));
//Menu Panel Set-up
cornerPanel.add(currentNumPanel);
bottomPanel.add(buttonPanel);
bottomPanel.add(cornerPanel);
menuPanel.setPreferredSize(new Dimension(1440, 840));
menuPanel.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
menuPanel.add(bottomPanel, BorderLayout.PAGE_END);
menuPanel.add(picPanel, BorderLayout.LINE_START);
menuPanel.add(printPanel, BorderLayout.LINE_END);
screen1Panel = extraScreenPanel.extraScreenPanel(piPhoto.mostRecent - 3);
screen2Panel = extraScreenPanel.extraScreenPanel(piPhoto.mostRecent - 2);
screen3Panel = extraScreenPanel.extraScreenPanel(piPhoto.mostRecent - 1);
screen4Panel = extraScreenPanel.extraScreenPanel(piPhoto.mostRecent);
screenPanel12.add(screen1Panel, BorderLayout.LINE_START);
screenPanel12.add(screen2Panel, BorderLayout.LINE_END);
screenPanel123.add(screenPanel12, BorderLayout.LINE_START);
screenPanel123.add(screen3Panel, BorderLayout.LINE_END);
screenPanel1234.add(screenPanel123, BorderLayout.LINE_START);
screenPanel1234.add(screen4Panel, BorderLayout.LINE_END);
screensPanel.add(screenPanel1234, BorderLayout.LINE_END);
deskScreen = extraScreenPanel.extraScreenPanel(dispNum);
wholePanel.add(menuPanel, BorderLayout.LINE_START);
wholePanel.add(screensPanel, BorderLayout.LINE_END);
wholePanel2.add(wholePanel, BorderLayout.LINE_START);
wholePanel2.add(deskScreen, BorderLayout.LINE_END);
frame.add(wholePanel2);
//Frame set-up and Initializing
JFrame.setDefaultLookAndFeelDecorated(true);
frame.setResizable(false);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
newImageRecieved.runCheck();
}
public static void repaintButtonPanel()
{
bottomPanel.removeAll();
bottomPanel.setPreferredSize(new Dimension(1440, 200));
buttonPanel = updateButtonPanel.updateButtonPanel(mostRecent);
buttonPanel.setPreferredSize(new Dimension(1120, 200));
cornerPanel.add(currentNumPanel);
bottomPanel.add(buttonPanel);
bottomPanel.add(cornerPanel);
menuPanel.add(bottomPanel, BorderLayout.PAGE_END);
frame.validate();
}
public static void repaintScreens()
{
wholePanel.remove(screensPanel);
screen1Panel.removeAll();
screen1Panel = extraScreenPanel.extraScreenPanel(piPhoto.mostRecent);
screen2Panel.removeAll();
screen2Panel = extraScreenPanel.extraScreenPanel(piPhoto.mostRecent - 1);
screen3Panel.removeAll();
screen3Panel = extraScreenPanel.extraScreenPanel(piPhoto.mostRecent - 2);
screen4Panel.removeAll();
screen4Panel = extraScreenPanel.extraScreenPanel(piPhoto.mostRecent - 3);
screenPanel12.add(screen1Panel, BorderLayout.LINE_START);
screenPanel12.add(screen2Panel, BorderLayout.LINE_END);
screenPanel123.add(screenPanel12, BorderLayout.LINE_START);
screenPanel123.add(screen3Panel, BorderLayout.LINE_END);
screenPanel1234.add(screenPanel123, BorderLayout.LINE_START);
screenPanel1234.add(screen4Panel, BorderLayout.LINE_END);
screensPanel.add(screenPanel1234, BorderLayout.LINE_END);
wholePanel.add(menuPanel, BorderLayout.LINE_START);
wholePanel.add(screensPanel, BorderLayout.LINE_END);
frame.validate();
}
}
the part that checks to see if new images are added to the file yet
public class newImageRecieved {
static int count = 0;
public static void runCheck()
{
int delay = 500;
ActionListener taskPerformer = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
newImageRecieved(piPhoto.mostRecent+1);
}
};
new Timer(delay, taskPerformer).start();
}
public static void newImageRecieved(int picNum)
{
String url[] = new String[5000];
String part1;
url[0] = "C:/PiPhotoPic/pic16.jpg";
for(Integer i=1;i<5000;i++){
if(i<10){part1 = "C:/temp/new0000000";}
else if(i<100){part1 = "C:/temp/new000000";}
else if(i<1000){part1 = "C:/temp/new00000";}
else {part1 = "C:/temp/new00000";}
String num = Integer.toString(i);
url[i]= part1 + num + ".jpg";
}
if(picNum<0){picNum=0;}
String ref = url[picNum];
piPhoto.frame.validate();
boolean exists = (new File(ref)).exists();
if(exists == true)
{
while (exists == true)
{
piPhoto.updateMostRecent(picNum);
ref = url[picNum + 1];
picNum = picNum + 1;
exists = (new File(ref)).exists();
}
piPhoto.updateMostRecent(picNum-1);
piPhoto.repaintButtonPanel();
piPhoto.repaintScreens();
count=0;
}
// }
}
}

You might try a memory profiler such as YourKit

Solved it today. Turns out I didnt remove the image panels from the old method, aso that when i was repainting them I was painting over the old ones and the old ones were still there. So I just needed to add in removeAll() for all the panels that were being updated and the program ran fine without heapstack errors.

Well, you are creating an array of 5000 strings and start fill up most of them.