Develop Reference

Program adding too many buttons

I'm trying to make a checkers game and and all seams well so far, but when I hover over the button the graphics glitch out and I don't know why. Also it adds a lot of buttons to the top and when I move it around (resize) it adds more. It also adds more when I press any green buttons. And they are very tiny buttons at the top and I don't see where they pop up in my code.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Test {
private JButton Green;
private JButton Blue;
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame("Checkers");
JPanel contentPane = new JPanel();
GameListener listener = new GameListener() {
#Override
public void gameWasCompleted() {
contentPane.repaint();
}
#Override
public void startNewGame() {
System.out.println("button worked");
contentPane.repaint();
}
};
MainPane mainPane = new MainPane();
mainPane.setGameListener(listener);
contentPane.add(mainPane);
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public interface GameListener {
void gameWasCompleted();
void startNewGame();
}
public class MainPane extends JPanel implements MouseListener {
private GameListener gameListener;
public MainPane() {
addMouseListener(this);
}
public void setGameListener(GameListener gameListener) {
this.gameListener = gameListener;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(1000, 1000);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
int xshift;
int yshift = 0;
g.setColor(new Color(0, 0, 0));
for (int i = 0; i < 4; i++) {
xshift = 125;
for (int j = 0; j < 4; j++) {
g.fillRect(xshift, yshift, 125, 125);
xshift += 250;
}
xshift = 0;
yshift += 125;
for (int k = 0; k < 4; k++) {
g.fillRect(xshift, yshift, 125, 125);
xshift += 250;
}
yshift += 125;
}
initalprnt(g);
}
protected void initalprnt(Graphics g) {
int xshift = 125;
int yshift = 0;
g.setColor(new Color(0, 100, 0));
for (int i = 0; i < 3; i++) {
if (i == 2) {
xshift = 125;
}
for (int j = 0; j < 4; j++) {
g.fillOval(xshift, yshift, 125, 125);
Green = new JButton();
Green.setBackground(new Color(0, 100, 0, 0));
Green.setBounds(xshift, yshift, 125, 125);
add(Green);
xshift += 250;
}
xshift = 0;
yshift += 125;
}
yshift += 250;
g.setColor(new Color(0, 0, 100));
for (int k = 0; k < 3; k++) {
if (k == 2) {
xshift = 0;
}
for (int j = 0; j < 4; j++) {
g.fillOval(xshift, yshift, 125, 125);
Blue = new JButton();
Blue.setBackground(new Color(0, 0, 100, 0));
Blue.setBounds(xshift, yshift, 125, 125);
add(Blue);
xshift += 250;
}
xshift = 125;
yshift += 125;
}
buttons();
}
public void buttons() {
Green.addActionListener(e -> {
System.out.println("this does something");
gameListener.startNewGame();
});
Blue.addActionListener(e -> {
System.out.println("this did something");
gameListener.startNewGame();
});
}
public void mouseClicked(MouseEvent e) {}
public void mousePressed(MouseEvent e) {}
public void mouseReleased(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
}
}

Basic rule of thumb, do not, under any circumstances, modify the state of the component (or any other component) during a paint pass. This can (and probably will) cause the component to be rescheduled for another paint pass and you'll end up in an infinite loop.
There are so many ways you "might" achieve this, for example, you could use JButtons in a GridLayout.
Then all you need to is devise an appropriate model and delegation/observer workflow to keep the UI in sync with the model
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.HashMap;
import java.util.Map;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
BoardPane boardPane = new BoardPane();
boardPane.setBoardListener(new BoardListener() {
#Override
public void cellWasSelected(Point p) {
System.out.println("Cell selected " + p);
}
});
frame.add(boardPane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public interface BoardListener {
public void cellWasSelected(Point p);
}
public class BoardPane extends JPanel {
private Map<Point, JButton> cells = new HashMap<>();
private BoardListener boardListener;
public BoardPane() {
int gridSize = 8 * 8;
setLayout(new GridLayout(8, 8));
int index = 0;
for (int row = 0; row < 8; row++) {
int xPos = (row % 2 == 0) ? gridSize : 0;
for (int col = 0; col < 8; col++) {
index++;
JButton btn = new JButton();
btn.setOpaque(true);
btn.setFocusPainted(false);
btn.setBorderPainted(false);
// I'd prefer to rely on something like
// an image, such as an empty image for
// cells which are empty
btn.setPreferredSize(new Dimension(100, 100));
if (index % 2 == 0) {
btn.setBackground(Color.BLACK);
btn.setForeground(Color.WHITE);
} else {
btn.setBackground(Color.WHITE);
btn.setForeground(Color.BLACK);
}
Point p = new Point(col, row);
btn.putClientProperty("cell", p);
cells.put(p, btn);
add(btn);
btn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
BoardListener listener = getBoardListener();
if (listener == null) {
return;
}
Point p = (Point)btn.getClientProperty("cell");
listener.cellWasSelected(p);
}
});
}
index++;
}
}
public void setBoardListener(BoardListener boardListener) {
this.boardListener = boardListener;
}
public BoardListener getBoardListener() {
return boardListener;
}
}
}
Generally, I would use either a completely component based or custom painting based solution and avoid mixing the two.
Remember, the board should be focused only on what the board needs to do and shouldn't be doing anything else. This is the point of "separation of concerns/responsibility"
A far more complex solution might use a custom layout to manage components on top of a custom painted board, but that is, simply way beyond the scope of the question or your abilities at this time

I cannot pull values from an array in a different class

The printout of the array lifegrid2 just gives all zeros. I tested the lifegrid array in MyPanel and that is populating, but the values are pulling through as zeros. I checked by putting some values in lifegrid2 and they are being wiped, so it is pulling through from MyPanel, but only zeros. There are no errors being reported.
I have made a small test program with a 2d array which does pull values through.
import javax.swing.SwingUtilities;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import java.awt.*;
import java.awt.event.*;
public class SwingPaintDemo3 {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
private static void createAndShowGUI() {
JFrame f = new JFrame("Swing Paint Demo");
f.setPreferredSize(new Dimension(1280,800));
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new MyPanel());
f.pack();
f.setVisible(true);
JPanel subPanel = new JPanel();
JButton start = new JButton("START");
subPanel.add(start);
start.setPreferredSize(new Dimension(100,50));
start.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae1) {
System.out.println("START");
int [][][] lifegrid2 = new int [12][12][2];
int temp;
for (int i=0; i<12; i++) {
for (int j=0; j<12; j++) {
**MyPanel obj = new MyPanel();
temp = obj.lifegrid [i][j][0];
lifegrid2 [i][j][0] = temp;**
if (j<11)
{System.out.print(lifegrid2 [j] [i] [0]);}
else
{System.out.println(lifegrid2 [j] [i] [0]);}}}
}
});
f.add(subPanel, BorderLayout.EAST);
}
}
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JPanel;
class MyPanel extends JPanel {
public int [][][] lifegrid = new int [12][12][2];
private int squareX = 1280;
private int squareY = 800;
private int gridX, gridY ;
public MyPanel() {
addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
squareX = e.getX();
squareY = e.getY();
if ((squareX>50 & squareX <550) & (squareY>50 & squareY <550) ){
gridX =(squareX-50)/50+1;
gridY =(squareY-50)/50+1;
squareX = (squareX -50)/50 * 50 + 50;
squareY = (squareY -50)/50 * 50 + 50;
System.out.println(gridX + " " + gridY);
lifegrid [gridX] [gridY] [0] = 1;
repaint(squareX,squareY,50,50);}
else {
}
}
});
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawString("This is my custom Panel!",10,20);
g.setColor(Color.RED);
g.fillRect(squareX,squareY,48,48);
g.setColor(Color.BLACK);
g.drawRect(squareX,squareY,48,48);
}
}

I have made a small test program with a 2d array
int [][][] lifegrid2 = new int [12][12][2];
That is a 3D array.
A 2D array is defined as:
int [][] lifegrid2 = new int [12][12];
The logic to initialize the array belongs in the constructor of your class:
MyPanel()
{
for (int i = 0; i < 12; i++) {
for (int j = 0; j < 12; j++) {
lifegrid [i][j] = 0)
}
}
}
Then your paintComponent() method needs to iterate through the 2D grid and only paint the grids that have a value of 1.
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
for (int i = 0; i < 12; i++) {
for (int j = 0; j < 12; j++) {
if (lifegrid[i][j] = 1)
// paint the grid
}
}
}
}
Edit:
As best as I can tell you are trying to create a grid based game. When you click on a cell in the grid the cell turns red. The are two common ways to approach this:
Use components. In this approach you have a parent panel using a GridLayout and you add a child panel to each cell in the grid. You would also add your MouseListener to each child panel. When you click on the child panel you change the background of the panel to red.
Do custom painting. In this approach you have a single JPanel. This class keep a 2D Array for the "state" of each cell in the grid. You add a single MouseListener to the panel. When you click on the panel you determine which cell was clicked and then you update the state of that cell. In the paintComponent() method you iterate through the 2D Array and paint each cell where that state has changed.
Your approach seems to be some kind of hybrid between the two and is not working.

Stuck with making Kakurasu game

We are learning in school java graphic and now we have to build a game called Kakurasu (https://www.brainbashers.com/showkakurasu.asp)
I'm so stuck and I don't know how to do it.
As far as I came. I've done a frame with a panel inside a panel which has 7x7 buttons that change from 0 to 1 and from white to green when pressed. The idea is that I make the first raw on the top and on the left to be the numbers 1-5 and then on the bottom and right side the random generated numbers.
This is my first code:
import javax.swing.*;
import java.awt.*;
public class Start {
public static JButton[][] gumbi;
public static void main(String[] args) {
buttons = new JButton[7][7];
JFrame window = new JFrame("Kakurasu");
JPanel panel = new JPanel(new BorderLayout());
JPanel playingField = new JPanel(new GridLayout(7, 7));
Listner1 p = new Listner1(buttons);
panel.add(playingField, BorderLayout.CENTER);
window.add(panel);
for (int i = 0; i < 7; i++) {
for (int j = 0; j < 7; j++) {
buttons[i][j] = new JButton("0");
playingField.add(buttons[i][j], BorderLayout.CENTER);
buttons[i][j].addActionListener(p);
buttons[i][j].setBackground(Color.WHITE);
}
}
window.setVisible(true);
window.setSize(500, 500);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
This is my second code:
import javax.swing.*;
import java.awt.*;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Poslusalec1 implements ActionListener {
public JButton[][] buttons;
public Listner1(JButton[][] gumbi) {
this.buttons = buttons;
}
public void actionPerformed(ActionEvent e) {
JButton button = (JButton) e.getSource();
String tmp = button.getText();
int n = Integer.parseInt(tmp);
n += 1;
if (n == 2) {
n = 0;
}
button.setText("" + n);
if (button.getBackground() == Color.WHITE) {
button.setBackground(Color.GREEN);
} else {
button.setBackground(Color.WHITE);
}
for (int i = 0; i < buttons.length; i++) {
for (int j = 0; j < buttons[i].length; j++) {
if (button == buttons[i][j]) {
System.out.println(i + ", " + j);
}
}
}
}
}
Is it possible to assign different actionlisteners to different buttons inside a gridlayout?
Thanks for any help.

I'm so stuck and I don't know how to do it.
To solve any computer problem, you break the problem down into smaller and smaller problems, until you're comfortable that you can code each small problem.
Generally, when coding a GUI, you should use the model / view / controller pattern.
In Java Swing, this means:
The view may read values from the model.
The view may not update the model.
The controller updates the model.
The controller repaints / revalidates the view.
So, let's create a model for a JButton. The model will hold the across value of the JButton, the down value of the JButton, and the background color of the JButton.
package com.ggl.testing;
import java.awt.Color;
public class KakurasuCell {
private final int acrossValue;
private final int downValue;
private Color backgroundColor;
public KakurasuCell(int acrossValue, int downValue, Color backgroundColor) {
this.acrossValue = acrossValue;
this.downValue = downValue;
this.backgroundColor = backgroundColor;
}
public Color getBackgroundColor() {
return backgroundColor;
}
public void setBackgroundColor(Color backgroundColor) {
this.backgroundColor = backgroundColor;
}
public int getAcrossValue() {
return acrossValue;
}
public int getDownValue() {
return downValue;
}
}
This is a Java object. It holds multiple types of values.
Now, we create another model for a grid of JButtons. You should recognize this from your code.
package com.ggl.testing;
import java.awt.Color;
public class KakurasuGrid {
private int gridWidth;
private KakurasuCell[][] cells;
public KakurasuGrid(int gridWidth) {
setGridWidth(gridWidth);
}
public int getGridWidth() {
return gridWidth;
}
public void setGridWidth(int gridWidth) {
this.gridWidth = gridWidth;
this.cells = new KakurasuCell[gridWidth][gridWidth];
setCells();
}
public KakurasuCell[][] getCells() {
return cells;
}
private void setCells() {
for (int i = 0; i < gridWidth; i++) {
for (int j = 0; j < gridWidth; j++) {
KakurasuCell cell = new KakurasuCell((j + 1), (i + 1),
Color.GRAY);
cells[i][j] = cell;
}
}
}
}
This should be enough to get you started. You still need to create the answers, create the GUI, and add the controller methods.

Super paint component not showing up (I have tried everything)

Hello guys I am currently having problems with making anything show with my paint component. I have tried numerous things that I have seen online and tried a lot of different things myself but i Just can't get it to show anything. I am trying to get my paint component to show a series of bars that move as an array being sorted using swing but i can't even get it ti show anything. Any help would be appreciated.
package proj2;
import java.awt.*;
import java.awt.event.*;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingWorker;
public class project2 extends JFrame
{
private JButton button1 = new JButton("Insertion");
private UpdateTextFieldThread currentThread;
private int[] array = new int[15];
private Display display;
private class ButtonHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
Object src = e.getSource();
if (src == button1){
insertionSort(array);
(new UpdateTextFieldThread()).execute();
}
}
}
public project2()
{
setTitle("Sorting Charts");
setSize(400,250);
setDefaultCloseOperation(EXIT_ON_CLOSE);
for(int i=0; i<array.length;i++)
array[i]=(int) (Math.random()*100);
display=new Display();
ButtonHandler bh = new ButtonHandler();
button1.addActionListener(bh);
JPanel container = new JPanel();
container.setLayout(new GridLayout(2, 2));
container.add(button1);
JPanel masterPanel=new JPanel();
masterPanel.setLayout(new BorderLayout());
masterPanel.add(display, BorderLayout.SOUTH);
masterPanel.add(container, BorderLayout.NORTH);
setContentPane(container);
setVisible(true);
display.repaint();
}
private class Display extends JPanel {
private Color color = Color.RED;
//#Override
public void paintComponent(Graphics g) {
super.paintComponents(g);
g.setColor(Color.RED);
Dimension d = getSize();
int clientWidth = d.width;
int clientHeight = d.height;
int barWidth = clientWidth / array.length;
for(int i=0;i<array.length;i++){
int x=0;
int y=15;
int linethickness=5;
int linelength=10;
g.setColor(Color.red);
g.fillRect(x, clientHeight, linelength*array[i] , linethickness);
g.setColor(Color.black);
g.drawRect(x,clientHeight, linelength*array[i], linethickness);
x+=15;
}
}
}
private class UpdateTextFieldThread extends SwingWorker<Void, Integer>
{
protected Void doInBackground()
{
display.repaint();
return null;
//should have repaint method in here somewhere
/*for (int i = 0; i < 50; i++) {
publish(i);
try {
Thread.sleep(THREAD_DELAY);
} catch (InterruptedException e) { }
}
return null;*/
}
// The parameter here is a list of all published data
// since the last call to process. We are interested
// in displaying only the latest one on the GUI.
protected void process(java.util.List<Integer> list)
{
// textfield.setText("" + list.get(list.size() - 1));
}
}
public static <T extends Comparable<T>> void insertionSort(int[] hue2)
{
for (int i = 1; i < hue2.length; i++) {
int thingToInsert = hue2[i];
int j = i - 1;
while (j >= 0 && thingToInsert<hue2[j]) {
hue2[j+1] = hue2[j];
j--;
}
hue2[j+1] = thingToInsert;
}
}
public static void main(String[]args) {
new project2();
}
}

masterPanel.add(display, BorderLayout.SOUTH);
You are adding your Display panel to the SOUTH of a BorderLayout. The SOUTH constraint will respsect the preferred height of the component. Your component has a height of 0, to there is nothing to display.
Whenever you do custom painting you also need to override the getPreferredSize() method of the component to provide the appropriate size of the component so the layout managers can do there job.

Java - JPanel contains point method error

I have a 2d array of Grids (JPanels) that are added to another JPanel using the GridLayout. That JPanel is added to the JFrame. Whenever a click happens on the JFrame I'm attempting to take the Point of the click and determine if any of those Grids in the 2d array contain that Point.
I'm attempting to do this inside frame.addMouseListener...
I know the frame is registering the mouse clicks. For some reason the Grids don't register that they should be containing that Point. Can anyone explain this? if(theView[i][j].contains(me.getPoint())){ This is the line of code that seems to be failing me.
I originally attempted to have the Grids know when they were clicked on so I wouldn't have to coordinate between the frame and grids, but I couldn't get that to work.
Here's the level designer.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.io.*;
import javax.swing.*;
public class LevelDesigner extends JPanel implements ButtonListener{
private final int SIZE = 12;
private int [][] thePit;
private Grid [][] theView;
private ButtonPanel bp;
public static int val;
private int rows, cols;
private JPanel gridPanel;
private JFrame frame;
public LevelDesigner(int r, int c){
frame = new JFrame();
int h = 10, w = 10;
setVisible(true);
setLayout(new BorderLayout());
setBackground(Color.BLUE);
rows = r;
cols = c;
thePit = new int[r][c];
theView = new Grid[r][c];
gridPanel = new JPanel();
gridPanel.setVisible(true);
gridPanel.setBackground(Color.BLACK);
gridPanel.setPreferredSize(getMaximumSize());
GridLayout gridLayout = new GridLayout();
gridLayout.setColumns(cols);
gridLayout.setRows(rows);
gridPanel.setLayout(gridLayout);
for(int i = 0; i < r; i++){
for(int j = 0; j < c; j++){
theView[i][j] = new Grid(i, j, SIZE, this);
gridPanel.add(theView[i][j]);
}
}
String test [] = {"0", "1","2","3","4","save"};
bp = new ButtonPanel(test, this);
this.add(bp, BorderLayout.SOUTH);
this.add(gridPanel, BorderLayout.CENTER);
frame.addMouseListener(new MouseAdapter(){
public void mousePressed(MouseEvent me) {
for(int i = 0; i < rows; ++i){
for(int j = 0; j < cols; ++j){
if(theView[i][j].contains(me.getPoint())){
theView[i][j].actionPerformed(null);
return;
}
}
}
}
});
frame.setVisible(true);
frame.setExtendedState(java.awt.Frame.MAXIMIZED_BOTH);
frame.setTitle("Epic Crawl - Main Menu");
frame.pack();
frame.setLocationRelativeTo(null);
frame.repaint();
frame.add(this);
}
public String toString(){
int noRows = thePit.length;
int noColumns = thePit[0].length;
String s="";
for (int r=0;r<noRows;r++){
for (int c=0;c<noColumns;c++){
s=s + thePit[r][c] + " ";
}
s=s+"\n";
}
return(s);
}
public void notify( int i, int j){
thePit[i][j] = val;
}
public void print(){
final JFileChooser fc = new JFileChooser();
fc.setCurrentDirectory(new java.io.File("."));
int returnVal = fc.showSaveDialog( null);
if( returnVal == JFileChooser.APPROVE_OPTION ){
try{
PrintWriter p = new PrintWriter(
new File( fc.getSelectedFile().getName() ) );
System.out.println(" printing");
p.println( this );
p.close();
}
catch( Exception e){
System.out.println("ERROR: file not saved");
}
}
}
public void buttonPressed(String buttonLabel, int id){
if(id == 5)
print();
else
val = id;
}
public void buttonReleased( String buttonLabel, int buttonId ){}
public void buttonClicked( String buttonLabel, int buttonId ){}
public static void main(String arg[]){
LevelDesigner levelDesigner = new LevelDesigner(4, 4);
}
}
And here is the Grid.
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.InputStream;
import javax.imageio.ImageIO;
import javax.swing.BorderFactory;
import javax.swing.JPanel;
#SuppressWarnings("serial")
public class Grid extends JPanel implements ActionListener{
LevelDesigner grid;
int myI, myJ;
private String[] imageNames = {"dirt.png", "grass.png", "Door.png", "woodfloor.png", "32x32WoodFloor.png"};
BufferedImage gridImage;
private String imagePath;
public Grid(int i, int j, int size, LevelDesigner m){
imagePath = "";
grid = m;
myI = i;
myJ = j;
setBackground(Color.RED);
this.setBorder(BorderFactory.createLineBorder(Color.black));
this.setVisible(true);
}
#Override
public void actionPerformed(ActionEvent ae){
grid.notify(myI, myJ);
imagePath = "Images/" + imageNames[LevelDesigner.val];
gridImage = null;
InputStream input = this.getClass().getClassLoader().getResourceAsStream(imagePath);
try{
gridImage = ImageIO.read(input);
}catch(Exception e){System.err.println("Failed to load image");}
}
public void paintComponent(Graphics g){
super.paintComponent(g); // Important to call super class method
g.clearRect(0, 0, getWidth(), getHeight()); // Clear the board
g.drawImage(gridImage, 0, 0, getWidth(), getHeight(), null);
}
}

The contains method checks if the Point is within the boundaries of the JPanel but using a coordinate system relative to the JPanel. Instead consider using findComponentAt(Point p).
For example:
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.*;
public class TestMouseListener {
private static final int SIDE_COUNT = 4;
private JPanel mainPanel = new JPanel();
private MyGridCell[][] grid = new MyGridCell[SIDE_COUNT][SIDE_COUNT];
public TestMouseListener() {
mainPanel.setLayout(new GridLayout(SIDE_COUNT, SIDE_COUNT));
for (int i = 0; i < grid.length; i++) {
for (int j = 0; j < grid[i].length; j++) {
grid[i][j] = new MyGridCell();
mainPanel.add(grid[i][j].getMainComponent());
}
}
mainPanel.addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent e) {
Point p = e.getPoint();
Component c = mainPanel.findComponentAt(p);
for (MyGridCell[] gridRow : grid) {
for (MyGridCell myGridCell : gridRow) {
if (c == myGridCell.getMainComponent()) {
myGridCell.setLabelText("Pressed!");
} else {
myGridCell.setLabelText("");
}
}
}
}
});
}
public Component getMainComponent() {
return mainPanel;
}
private static void createAndShowGui() {
TestMouseListener mainPanel = new TestMouseListener();
JFrame frame = new JFrame("TestMouseListener");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel.getMainComponent());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class MyGridCell {
private static final int PREF_W = 200;
private static final int PREF_H = PREF_W;
#SuppressWarnings("serial")
private JPanel mainPanel = new JPanel() {
public Dimension getPreferredSize() {
return MyGridCell.this.getPreferredSize();
};
};
private JLabel label = new JLabel();
public MyGridCell() {
mainPanel.setBorder(BorderFactory.createLineBorder(Color.black));
mainPanel.setLayout(new GridBagLayout());
mainPanel.add(label);
}
public Component getMainComponent() {
return mainPanel;
}
public void setLabelText(String text) {
label.setText(text);
}
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
}

Component#contains "Checks whether this component "contains" the specified point, where the point's x and y coordinates are defined to be relative to the coordinate system of this component"
This means that the contains will only return true if the Point is within the bounds of 0 x 0 x width x height.
So if the component is position at 400x200 and is sized at 200x200 (for example). When you click within in, the mouse point will be between 400x200 and 600x400, which is actually out side of the relative position of the component (200x200) - confused yet...
Basically, you either need to convert the click point to a relative coordinate within the context of the component you are checking...
Point p = SwingUtilities.convertPoint(frame, me.getPoint(), theView[i][j])
if (theView[i][j].contains(p)) {...
Or use the components Rectangle bounds...
if (theView[i][j].getBounds().contains(me.getPoint())) {...
So, remember, mouse events are relative to the component that they were generated for