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Why the menubar is displayed twice, and the drawn lines only appear on a quarter of the page? [closed]

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I am learning Java. And I have a problem, certainly basic.
The menubar is displayed twice, and the drawn lines only appear on a quarter of the page.
Do you think there is a relation between the Panel and the JMenuBar ?
Do you think the problem is related to the repaint() method ?
Here is the code :
Class panel:
public class Panel extends JPanel {
private String colorName = "All";
private Color color = Color.RED;
private String shape = "Circle";
private int size1 = 30;
private int x = 0, y = 0;
private boolean allow = false;
#Override
public void paintComponent(Graphics g) {
// TODO Auto-generated method stub
super.paintComponent(g);
if (allow == true) {
if (colorName == "Red")
g.setColor(Color.RED);
else if (colorName == "Blue")
g.setColor(Color.BLUE);
else if (colorName == "All") {
int r = (int) ((Math.random()) * 256);
int v = (int) ((Math.random()) * 256);
int b = (int) ((Math.random()) * 256);
color = new Color(r, v, b);
g.setColor(color);
}
if (shape == "Circle")
g.fillOval(x, y, size1, size1);
if (shape == "Square")
g.fillRect(x, y, size1, size1);
}
repaint();
}
public String getColorName() {
return colorName;
}
public void setColorName(String colorName) {
this.colorName = colorName;
}
public boolean isAllow() {
return allow;
}
public void setAllow(boolean allow) {
this.allow = allow;
}
public String getShape() {
return shape;
}
public void setForme(String forme) {
this.shape = shape;
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
public int getSize1() {
return size1;
}
public void setSize1(int size1) {
this.size1 = size1;
}
}
Class frame :
public class Frame extends JFrame{
JMenuBar mb = new JMenuBar();
JMenu file = new JMenu("File");
JMenu edit = new JMenu("Edit");
Panel p = new Panel();
public Frame() {
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
this.setSize(400,400);
this.setTitle("Test");
this.addMouseListener(new MouseAdapter(){
#Override
public void mousePressed(MouseEvent e) {
int a = e.getX() - (p.getSize1()/2);
int b = e.getY() - (p.getSize1());
p.setX(a);
p.setY(b);
p.setAllow(true);
}
});
this.addMouseMotionListener(new MouseMotionListener() {
#Override
public void mouseMoved(MouseEvent e) {
}
#Override
public void mouseDragged(MouseEvent e) {
int a = e.getX() - (p.getSize1()/2);
int b = e.getY() - (p.getSize1());
p.setX(a);
p.setY(b);
p.setAllow(true);
}
});
mb.add(file);
mb.add(edit);
this.setJMenuBar(mb);
this.setLayout(new BorderLayout());
this.add(p, BorderLayout.CENTER);
this.setVisible(true);
}
public static void main(String[] args) {
new Frame();
}
}
Can you help me please?

You've a very bad typographical bug in your code:
#Override
public void paintComponent(Graphics g) {
// TODO Auto-generated method stub
super.paintComponents(g);
should be:
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Please note the difference in the super call since paintComponents != paintComponent
Also, don't compare Strings using == or !=. Use the equals(...) or the equalsIgnoreCase(...) method instead. Understand that == checks if the two object references are the same which is not what you're interested in. The methods on the other hand check if the two Strings have the same characters in the same order, and that's what matters here.
And so, not:
if (colorName == "Red") {
// ....
}
but rather:
if (colorName.equalsIgnoreCase("Red")) {
// ....
}
Also, never call repaint() within a painting method. Also, don't randomize the painting or change object state within paintComponent since you do not have control over when or if the method will be called. Randomize in a listener, such as the mouse listener, and if you need animation separate from what the mouse listener provides, use a Swing Timer
ALSO
This:
public int getX() {
// ...
}
Overrides a key method of JPanel inherited from the Component class, that is key to placement of the JPanel, same for getY(). Rename those methods ASAP

Paint method not painting Java

My paint method doesnt seem to paint my 20x20 cells. I have a boolean array for the cells to control their state and that if true, call the cells paint method, a cell is painted however I have two problems;
Only one is painted at a time which is odd because i should have a 40x40 array of booleans meaning i have 40x40 cells
They dont actually paint exactly where I click. I do not know how this is the case as when I get the co-ordinates of my click I immediately place those co-ordinates as my x, and y values in my paint method.
Main
import javax.swing.*;
import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.image.BufferStrategy;
public class mainApplication extends JFrame implements Runnable, MouseListener {
private static final Dimension windowsize = new Dimension(80, 600);
private BufferStrategy strategy;
private Graphics offscreenGraphics;
private static boolean isGraphicsInitialised = false;
private static int rows = 40;
private static int columns = 40;
private static int height = windowsize.height;
private static int width = windowsize.width;
private static Cells cells = new Cells();
private int xArrayElement,yArrayElement, xPosition, yPosition;
private static boolean gameState[][] = new boolean[rows][columns];
public mainApplication() {
System.out.println(System.getProperty("user.dir"));
setDefaultCloseOperation(EXIT_ON_CLOSE);
Dimension screensize = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
int x = screensize.width / 2 - windowsize.width / 2;
int y = screensize.height / 2 - windowsize.height / 2;
setBounds(x, y, screensize.width, screensize.height);
setVisible(true);
createBufferStrategy(2);
strategy = getBufferStrategy();
offscreenGraphics = strategy.getDrawGraphics();
isGraphicsInitialised = true;
// MouseEvent mouseEvent = new MouseEvent();
addMouseListener(this);
// addMouseMotionListener(MouseEvent);
Thread t = new Thread(this);
t.start();
}
public void mousePressed(MouseEvent e) { }
public void mouseReleased(MouseEvent e) { }
public void mouseEntered(MouseEvent e) { }
public void mouseExited(MouseEvent e) { }
public void mouseClicked(MouseEvent e) {
if(e.getClickCount() == 1){
xPosition = e.getX();
yPosition = e.getY();
cells.setPosition(xPosition,yPosition);
xArrayElement = (xPosition/20);
yArrayElement = (yPosition/20);
if(gameState[xArrayElement][yArrayElement]){
gameState[xArrayElement][yArrayElement] = false;
}
else if (!gameState[xArrayElement][yArrayElement]) {
gameState[xArrayElement][yArrayElement] = true;
}
else(gameState[xArrayElement][yArrayElement]) = true;
}
}
#Override
public void run() {
while (true) {
try { //threads entry point
Thread.sleep(20); //forces us to catch exception
}
catch (InterruptedException e) {
}
this.repaint();
}
}
public void paint(Graphics g) {
if (isGraphicsInitialised) {
g = strategy.getDrawGraphics();
g.setColor(Color.BLACK);
g.fillRect(0, 0, 800, 800);
if (gameState[xArrayElement][yArrayElement]) {
g.setColor(Color.WHITE);
cells.paint(g);
System.out.println(xPosition);
}
else if (!gameState[xArrayElement][yArrayElement]) {
g.setColor(Color.BLACK);
g.fillRect(xPosition, yPosition, 20, 20);
}
strategy.show();
}
}
public static void main(String[]args){
mainApplication test = new mainApplication();
}
}
Cell Class
import java.awt.*;
public class Cells {
int x;
int y;
public Cells(){
}
public void setPosition(int xi, int xj){
x = xi;
y = xi;
}
public boolean cellState(boolean visible){
return visible;
}
public void paint(Graphics g){
g.drawRect(x, y, 20,20);
}
}

You are doing a number of things wrong. My first suggestion would be to forget about offscreen graphics and ensure you are doing what you want. You can always create an image latter. Here are some basic guidelines:
Don't extend JFrame. Use an instance.
Extend JPanel or create a class that extends JPanel and add to frame instance
Then override paintComponent(g) and use that graphics context to draw.
Here is an earlier answer that may help Can't add Graphics into JPanel in Java
More information may be found in the Java Tutorials on painting.
Updated. It took me a few minutes to find this.
public void setPosition(int xi, int xj){
x = xi;
y = xi; // <--- should be xj
}
Regarding (1) above. You must repaint every cell each time you enter paintComponent. This means you will need to iterate across the list and paint them in the correct spot. Right now you are only painting one upon each entry.
A couple more suggestions. Instead of messing with the thread and calling repaint every 20ms in a loop, why not just invoke repaint in the mouseClicked() method.
If you do eventually need to paint every 20ms. I suggest using a swing Timer as follows: (check JavaDoc to ensure I got the syntax correct!!)
Timer timer = new Timer(0, (ev)-> frame.repaint());
timer.setDelay(20);
timer.start();
And you can create your own mouseListener class and extending MouseAdapter. The purpose of these adapter classes is to keep the clutter down so you don't have to have empty methods to satisfy the interface requirements. Put the class inside your main class so it has access to the appropriate data structures. Then just add an instance of it to the mouse listener of the target Component.

Java - How to Create a MultiThreaded Game using SwingWorker

I want to Create a [1 Player vs PC] Game with Threads.
we have 10*10 two Colors Shapes in our board like this :
when the Player clicks on BLUE Circles , Their color turns into Gray.
at the other side PC should turn all RED Rectangles into Gray.
the WINNER is who Clears all his/her own Shapes Earlier.
Code for The Player works fine but,
My Problem is in Implementing The PC side of the Game, as i read in this article i should use SwingWorker to Implement Threading in GUI.
it's my first time using SwingWorkers and i don't know how it should be to works properly.
Here is my Codes :
The Main Class
public class BubblePopGame {
public static final Color DEFAULT_COLOR1 = Color.BLUE;
public static final Color DEFAULT_COLOR2 = Color.RED;
public BubblePopGame() {
List<ShapeItem> shapes = new ArrayList<ShapeItem>();
int Total = 10;
for (int i = 1; i <= Total; i++) {
for (int j = 1; j <= Total; j++) {
if ((i + j) % 2 == 0) {
shapes.add(new ShapeItem(new Ellipse2D.Double(i * 25, j * 25, 20, 20),
DEFAULT_COLOR1));
} else {
shapes.add(new ShapeItem(new Rectangle2D.Double(i * 25, j * 25, 20, 20),
DEFAULT_COLOR2));
}
}
}
JFrame frame = new JFrame("Bubble Pop Quest!!");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ShapesPanel panel = new ShapesPanel(shapes);
frame.add(panel);
frame.setLocationByPlatform(true);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new BubblePopGame();
}
});
}
}
Shape Item Class
public class ShapeItem {
private Shape shape;
private Color color;
public ShapeItem(Shape shape, Color color) {
super();
this.shape = shape;
this.color = color;
}
public Shape getShape() {
return shape;
}
public void setShape(Shape shape) {
this.shape = shape;
}
public Color getColor() {
return color;
}
public void setColor(Color color) {
this.color = color;
}
}
ShapesPanel Class
public class ShapesPanel extends JPanel {
private List<ShapeItem> shapes;
private Random rand = new Random();
private SwingWorker<Boolean, Integer> worker;
public ShapesPanel(List<ShapeItem> shapesList) {
this.shapes = shapesList;
worker = new SwingWorker<Boolean, Integer>() {
#Override
protected Boolean doInBackground() throws Exception {
while (true) {
Thread.sleep(200);
int dim = rand.nextInt(300);
publish(dim);
return true;
}
}
#Override
protected void done() {
Boolean Status;
try {
Status = get();
System.out.println(Status);
super.done(); //To change body of generated methods, choose Tools | Templates.
} catch (InterruptedException ex) {
Logger.getLogger(ShapesPanel.class.getName()).log(Level.SEVERE, null, ex);
} catch (ExecutionException ex) {
Logger.getLogger(ShapesPanel.class.getName()).log(Level.SEVERE, null, ex);
}
}
#Override
protected void process(List<Integer> chunks) {
int mostRecentValue = chunks.get(chunks.size()-1);
System.out.println(mostRecentValue);
Color color2 = Color.LIGHT_GRAY;
ShapeItem tmpShape = shapes.get(mostRecentValue);
if(tmpShape.getColor()==Color.RED){
tmpShape.setColor(color2);
}
repaint();
}
};
worker.execute ();
addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
Color color1 = Color.LIGHT_GRAY;
for (ShapeItem item : shapes) {
if (item.getColor() == Color.BLUE) {
if (item.getShape().contains(e.getPoint())) {
item.setColor(color1);
}
}
}
repaint();
}
});
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g.create();
for (ShapeItem item : shapes) {
g2.setColor(item.getColor());
g2.fill(item.getShape());
}
g2.dispose();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
private Color getRandomColor() {
return new Color(rand.nextFloat(), rand.nextFloat(),
rand.nextFloat());
}
}

If I understood your code correctly, you are making a game where the human player has to click as fast as possible on all of his shapes while the PC is randomly clicking on shapes as well. The first one to clear all of his shapes win.
If that is correct, you probably want to adjust your SwingWorker to
loop until the game is finished. Currently your loop exit the first time the end of the loop is reached due to the return statement
Since you are not doing anything with the boolean return value of the SwingWorker, you might as well let it return void
No need to call get in the done method. The moment that method is called, the SwingWorker has finished. You only seem interested in the intermediate results
In the process method, you might want to loop over all values. Note that the process method is not called each time you publish something. The values you publish are grouped and passed in bulk to the process method when the EDT (Event Dispatch Thread) is available

Switch imageIcon in java?

I have many planes(threads) that move in window, and I want switch the ImageIcon according to the direction of the plane.
For example: if a plane goes to the right, the imageIcon of the plane is right and then plane goes to the left, exchange the imageIcon for the plane is left.
How can I do that in method paintComponent?
Sorry for my bad english.

If you're talking about swapping the ImageIcon displayed by a JLabel, then you should not switch ImageIcons in paintComponent but rather should do this in the non-paintComponent region of code, perhaps in a Swing Timer. Even if you're not talking about a JLabel, the paintComponent method should not be used for changing the state of an object.
Your question however leaves too much unsaid to allow us to be able to answer it completely and well. Consider telling and showing more.

If you are looking for a logic thingy, then a small example is here, though you might have to modify it for your needs.
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.swing.*;
public class FlyingAeroplane
{
private Animation animation;
private Timer timer;
private ActionListener timerAction = new ActionListener()
{
#Override
public void actionPerformed(ActionEvent ae)
{
animation.setValues();
}
};
private void displayGUI()
{
JFrame frame = new JFrame("Aeroplane Flying");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
animation = new Animation();
frame.setContentPane(animation);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
timer = new Timer(100, timerAction);
timer.start();
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
new FlyingAeroplane().displayGUI();
}
});
}
}
class Animation extends JPanel
{
private final int HEIGHT = 150;
private final int WIDTH = 200;
private int x;
private int y;
private ImageIcon image;
private boolean flag;
private Random random;
public Animation()
{
x = 0;
y = 0;
image = new ImageIcon(getClass().getResource("/image/aeroplaneright.jpeg"));
flag = true;
random = new Random();
}
public void setValues()
{
x = getXOfImage();
y = random.nextInt(70);
repaint();
}
private int getXOfImage()
{
if (flag)
{
if ((x + image.getIconWidth()) == WIDTH)
{
flag = false;
x--;
return x;
}
x++;
image = new ImageIcon(getClass().getResource("/image/aeroplaneright.jpeg"));
}
else if (!flag)
{
if (x == 0)
{
flag = true;
x++;
return x;
}
x--;
image = new ImageIcon(getClass().getResource("/image/aeroplaneleft.jpeg"));
}
return x;
}
#Override
public Dimension getPreferredSize()
{
return (new Dimension(WIDTH, HEIGHT));
}
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawImage(image.getImage(), x, y, this);
}
}
IMAGES USED :

On setting the direction you should set the image icon too, or have a getImageIcon(direction).
In the paintComponent no heavy logic should happen; it should be as fast as possible. You have no (total) control when and how often paintComponent is called.

Remembering where a mouse clicked? ArrayLists? HashCodes?

Sorry guys, I deleted my APPLES and CATS example :) Here's the updated version of my question!
I'm losing my sanity here. I need someone who can enlighten me. I've tried a couple of times explaining my problem here. Hopefully, this time, my question will be easier to understand.
Basically I have this frame, and there's an image displayed. There is a JList on the right, and there is another panel for JLabels at the bottom. Here's a screencap of my frame.
When I click on the image, a JOptionPane pops out, like so. And I enter my input. My JList is an ArrayList, so everything I input is added to the JList and the JPanel at the bottom.
Now, when I hover on the the part where I clicked, you noticed that the square disappeared). It only appears when I click the image, and when I hover the label at the bottom. My labels, as of now are LOLZ NOSE and INPUT HERE.
What I want to do is when I hover on the label, for example INPUT HERE, it shows the square again, featuring the part where I clicked. My problem now is when I click on NOSE, which is supposed to be showing a square on the nose part and a the name NOSE with black bg, IT IS NOT SHOWING. Also, only the last label's square is shown, disregarding the other labels' position clicked.
How do I get a label to remember the position of the click I make? People said I should use ArrayLists or HashCodes however I have no idea how to implement them. Thank you to anyone who can help.
Edit: I've already done the rectangle, btw. It's showing only for the last label inputted. Here are some of the code snippets requested!
How I'm setting the text on JLabel and updating the JList:
public void updateLabel(){
StringBuilder text = new StringBuilder(); //creates empty builder, capacity 16
for(Object s: tagModel.toArray()) //returns an array containing the elements of the tagModel
text.append(" " + s);
repaint();
hoverLabel.setText(text.toString()); //returns a String
hoverLabel.addMouseMotionListener(this);
hoverPanel.add(hoverLabel);
}
My mouseListener upon click:
#Override
public void mouseClicked(MouseEvent event) {
// TODO Auto-generated method stub
x = event.getX();
y = event.getY();
isRectPresent = true;
repaint();
input = JOptionPane.showInputDialog("Enter tag name:");
if((input != null) && !input.isEmpty()){
tagModel.addElement(input);
}
}
My mouseMotionListener upon hovering:
#Override
public void mouseMoved(MouseEvent e) {
// TODO Auto-generated method stub
xpos = e.getX(); //gets where the mouse moved
ypos = e.getY();
//checks if the mouse is inside the bounds of the rectangle
if (xpos > x && xpos < x + 100 && ypos > y && ypos < y + 100)
isRectPresent = false;
if(e.getSource() == hoverLabel){
isRectPresent = true;
repaint();
}
repaint();
}
How I'm painting:
public void paintComponent(Graphics g){
Graphics2D g2 = (Graphics2D) g;
g2.drawImage(image, 0, 0, null);
if(image != null && isRectPresent){
Stroke stroke = g2.getStroke();
g2.setStroke(new BasicStroke(4));
g2.setColor(Color.WHITE);
g2.drawRect(x-50, y-50, 100, 100);
g2.setStroke(stroke);
}else{
if(xpos > x && xpos < x + 100 && ypos > y && ypos < y + 100){
g.setColor(Color.BLACK);
g.fillRect(x-50, y-50, 100, 25);
g.setColor(Color.WHITE);
g.setFont(new Font("Tahoma", Font.BOLD, 12));
g.drawString(input, x-30, y-30);
}
}
}
If you want me to add some more snippets, just tell me! :)

You should create a HashMap, say something like:
Map linkSet = new HashMap();
And whenever you click on the drawing and create a label, add the JLabel and the point on the image to the set using the put method with the JLabel as the key and the Point as the value. Then in the JLabel's MouseMotionListener, use your label as a key and obtain the corresponding point from the set using the map's get(...) method.
edit:
Corrected as per alicedimarco's comment. Again, thanks!
edit 2
I think you want again to use a Map. If you have a Map, you can have it retrieve the Point of interest from the JLabel's or the JList's String, and then pass this Point to the class that's drawing the image and let it use the Point to draw a rectangle. For instance you could give the image drawing class a Point field called displayPoint, and a method called setDisplayPoint(Point p). It can be as simple as this:
public void setDisplayPoint(Point p) {
this.displayPoint = p;
repaint();
}
and assuming that the object of interest is centered at that point, use the displayPoint in the paintComponent method:
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// draw image
if (img != null) {
g.drawImage(img, X_SHIFT, Y_SHIFT, null);
}
// if displayPoint not null, draw the surrounding rectangle
if (displayPoint != null) {
g.setColor(RECT_COLOR);
int x = displayPoint.x - RECT_WIDTH / 2;
int y = displayPoint.y - RECT_WIDTH / 2;
int width = RECT_WIDTH;
int height = RECT_WIDTH;
g.drawRect(x, y, width, height);
}
}
edit 3:
To get mouse clicks, it's quite easy, simply add a MouseListener to the component that holds the image:
// !! added
imgRect.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
imgMousePressed(e);
}
});
And in your code that is called from this mouse listener, use a JOptionPane to get the user's choice of tag name, and add the resulting String to both the listDataModel so that it is seen in the JList and also in the stringPointMap together with the Point obtained from the MouseEvent so that you can map the String to the Point and be able to retrieve it:
// !! added
private void imgMousePressed(MouseEvent e) {
String result = JOptionPane.showInputDialog(this,
"Please enter name for this point on image:");
if (result != null) {
stringPointMap.put(result, e.getPoint());
listDataModel.addElement(result);
}
}
That's it.
Then putting it all together:
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class ImageRectMain extends JPanel {
private ImageRect imgRect;
private DefaultListModel listDataModel = new DefaultListModel();
private JList list = new JList(listDataModel);
private Map<String, Point> stringPointMap = new HashMap<String, Point>();
public ImageRectMain() {
String nose = "Nose";
String ear = "Ear";
String rightEye = "Right Eye";
String leftEye = "Left Eye";
listDataModel.addElement(ear);
listDataModel.addElement(nose);
listDataModel.addElement(rightEye);
listDataModel.addElement(leftEye);
stringPointMap.put(nose, new Point(480, 500));
stringPointMap.put(ear, new Point(270, 230));
stringPointMap.put(rightEye, new Point(380, 390));
stringPointMap.put(leftEye, new Point(662, 440));
MouseAdapter listMouseAdapter = new MouseAdapter() {
#Override
public void mouseMoved(MouseEvent e) {
listMouseMoved(e);
}
#Override
public void mouseExited(MouseEvent e) {
listMouseExited(e);
}
};
list.addMouseMotionListener(listMouseAdapter);
list.addMouseListener(listMouseAdapter);
try {
imgRect = new ImageRect();
// !! added
imgRect.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
imgMousePressed(e);
}
});
JPanel eastPanel = new JPanel();
eastPanel.setLayout(new BoxLayout(eastPanel, BoxLayout.PAGE_AXIS));
eastPanel.add(new JLabel("You have tagged the following:"));
eastPanel.add(new JScrollPane(list));
eastPanel.add(Box.createVerticalGlue());
eastPanel.add(Box.createVerticalGlue());
eastPanel.add(Box.createVerticalGlue());
eastPanel.add(Box.createVerticalGlue());
setLayout(new BorderLayout());
add(imgRect, BorderLayout.CENTER);
add(eastPanel, BorderLayout.EAST);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
// !! added
private void imgMousePressed(MouseEvent e) {
String result = JOptionPane.showInputDialog(this,
"Please enter name for this point on image:");
if (result != null) {
stringPointMap.put(result, e.getPoint());
listDataModel.addElement(result);
}
}
private void listMouseExited(MouseEvent e) {
imgRect.setDisplayPoint(null);
}
private void listMouseMoved(MouseEvent e) {
int index = list.locationToIndex(e.getPoint());
Object value = listDataModel.get(index);
if (value != null) {
Point point = stringPointMap.get(value.toString());
if (point != null) {
imgRect.setDisplayPoint(point);
}
}
}
private static void createAndShowGui() {
JFrame frame = new JFrame("ImageRectMain");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new ImageRectMain());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
#SuppressWarnings("serial")
class ImageRect extends JPanel {
public static final String IMAGE_PATH = "http://i.stack.imgur.com/7oNzg.jpg";
private static final int DEFAULT_W = 687;
private static final int DEFAULT_H = 636;
private static final int X_SHIFT = -6;
private static final int Y_SHIFT = -26;
private static final Color RECT_COLOR = Color.pink;
private static final int RECT_WIDTH = 40;
private BufferedImage img;
private Point displayPoint = null;
public ImageRect() throws MalformedURLException, IOException {
img = ImageIO.read(new URL(IMAGE_PATH));
}
public void setDisplayPoint(Point p) {
this.displayPoint = p;
repaint();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
g.drawImage(img, X_SHIFT, Y_SHIFT, null);
}
if (displayPoint != null) {
g.setColor(RECT_COLOR);
int x = displayPoint.x - RECT_WIDTH / 2;
int y = displayPoint.y - RECT_WIDTH / 2;
int width = RECT_WIDTH;
int height = RECT_WIDTH;
g.drawRect(x, y, width, height);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(DEFAULT_W, DEFAULT_H);
}
}

One nice feature of a JList is that you can story any object in it. You're not limited to strings. When objects are stored in JLists, swing will call the object's toString() method, and display it in the list.
Knowing this, you can now write your own class that stores the name of your selection label and the coordinates of the box. This object's toString() method will return the name of the label, which will make the right thing appear in the JList.
Then, in the selection event handler for the JList, you can get your custom object out, and retrieve the box coordinates stored in it, and draw them on the screen. No need to fuss with other containers (although knowing how to use them is a good thing to).
Ok, Create a class like this...
public class MyLabel {
private int x;
private int y;
private String text;
public MyLabel (String text, int x, int y) {
this.text = text;
// assign x and y too...
}
#Override
public String toString() {
return label;
}
public int getX() {
return x;
}
// similar function to getY()
}
The class above overrides toString(), so when you put it in a JList, it will use the call to toString() to determine what to display, and since this toString implementation returns the label name you'll see that in the list.
And add those into your JList instead of Strings. Then at some point in your code you'll do something like this...
// this is pseudocode, method names may not be correct...
MyLabel ml = (MyLabel)jList.getSelectedItem();
int x = ml.getX();
int y = ml.getY();
// draw the box...
Hope that helps.