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JPanel doesn't get new values (anymore)

So, I'm trying to program a Game of Life simulation (Conway), and I want to show it in a JFrame.
For this purpose, I've created a JPanel, and it works perfectly, until I try to actually show a new generation. With prints, I've figured out, that the list is actually correct inside the newGeneration() method, but when paint(Graphics g) gets called (aka, when I try to repaint the JFrame), the list isn't updating.
I'm sure I've missed something obvious, and I'm not well versed in Java, but it's just getting so annoying. I'd really appreciate your help.
Here's my code;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class Main {
public static void main(String[] args) {
new GameOfLife();
}
}
class GameOfLife {
// Initialising all class wide variables; sorted by type
JFrame frame = new JFrame("Game of Life");
JPanel panel;
Scanner gameSize = new Scanner(System.in);
String dimensions;
String splitHorizontal;
String splitVertical;
String confirmation;
Boolean accepted = false;
Integer split;
Integer horizontal;
Integer vertical;
Integer livingNeighbours;
int[][] cells;
int[][] newCells;
public GameOfLife() {
// Prompt for game Size
System.out.println("Please enter your game size in the following format; 'Horizontal,Vertical'");
// Run until viable game Size has been chosen
while (!accepted) {
dimensions = gameSize.nextLine();
// Check for correct format
if (dimensions.contains(",")) {
split = dimensions.indexOf(",");
splitHorizontal = dimensions.substring(0, split);
splitVertical = dimensions.substring(split + 1);
// Check for validity of inputs
if (splitHorizontal.matches("[0-9]+") && splitVertical.matches("[0-9]+")) {
horizontal = Integer.parseInt(dimensions.substring(0, split));
vertical = Integer.parseInt(dimensions.substring(split + 1));
// Check for game Size
if (horizontal > 1000 || vertical > 1000) {
System.out.println("A game of this Size may take too long to load.");
} else {
// Confirmation Prompt
System.out.println("Your game will contain " + horizontal + " columns, and " + vertical + " rows, please confirm (Y/N)");
confirmation = gameSize.nextLine();
// Check for confirmation, anything invalid is ignored
if (confirmation.matches("Y")) {
accepted = true;
System.out.println("Thank you for your confirmation. Please select live cells. Once your happy with your game, press Spacebar to start the Simulation.");
// Setting parameters depending on Size
frame.setSize(horizontal * 25 + 17, vertical * 25 + 40);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
}
}
// Prompt asking for new dimensions in case of invalid dimensions or non confirmation
if (!accepted) {
System.out.println("Please enter different dimensions.");
}
}
// Creating list of cells
cells = new int[horizontal][vertical];
// Showing the empty panel for selection of live cells
panel = new PaintCells(horizontal, vertical, cells);
frame.add(panel);
// Select live cells
panel.addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent e) {
if (cells[(int) Math.ceil(e.getX() / 25)][(int) Math.ceil(e.getY() / 25)] == 1) {
cells[(int) Math.ceil(e.getX() / 25)][(int) Math.ceil(e.getY() / 25)] = 0;
} else {
cells[(int) Math.ceil(e.getX() / 25)][(int) Math.ceil(e.getY() / 25)] = 1;
}
frame.repaint();
}
});
// Simulation start
frame.addKeyListener(new KeyListener() {
#Override
public void keyTyped(KeyEvent e) {
if (e.getKeyChar() == ' ') {
newGeneration();
}
}
#Override
public void keyPressed(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
}
});
}
// Generating new generations
void newGeneration() {
newCells = new int[horizontal][vertical];
// Pause inbetween generations
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
/*
* Way of Life Rules:
* Living cells with 2 or 3 living neighbours live on to the next generation.
* Dead cells with exactly 3 living neighbours become living cells in the next generation.
* Every other living cell dies.
*/
// iterate through every cell
for (int l = 0; l < vertical; l++) {
for (int k = 0; k < horizontal; k++) {
livingNeighbours = 0;
// check amount of neighbours
if (k - 1 > -1) {
if (l - 1 > -1) {
if (cells[k - 1][l - 1] == 1) {
livingNeighbours++;
}
}
if (l + 1 < vertical) {
if (cells[k - 1][l + 1] == 1) {
livingNeighbours++;
}
}
if (cells[k - 1][l] == 1) {
livingNeighbours++;
}
}
if (k + 1 < horizontal) {
if (l - 1 >= 0) {
if (cells[k + 1][l - 1] == 1) {
livingNeighbours++;
}
}
if (l + 1 < vertical) {
if (cells[k + 1][l + 1] == 1) {
livingNeighbours++;
}
}
if (cells[k + 1][l] == 1) {
livingNeighbours++;
}
}
if (l - 1 >= 0) {
if (cells[k][l - 1] == 1) {
livingNeighbours++;
}
}
if (l + 1 < vertical) {
if (cells[k][l + 1] == 1) {
livingNeighbours++;
}
}
// change cell value depending on amount of neighbours
if (cells[k][l] == 1) {
if (livingNeighbours < 2 || livingNeighbours > 3) {
newCells[k][l] = 0;
} else {
newCells[k][l] = 1;
}
} else {
if (livingNeighbours == 3) {
newCells[k][l] = 1;
}
}
}
}
cells = newCells;
frame.validate();
frame.paint(frame.getGraphics());
newGeneration();
}
}
// Our canvas
class PaintCells extends JPanel {
private Integer horizontal;
private Integer vertical;
private int[][] newOriginalCells;
// Get our X and Y from the original prompts
public PaintCells(Integer originalHorizontal, Integer originalVertical, int[][] originalCells) {
this.horizontal = originalHorizontal;
this.vertical = originalVertical;
this.newOriginalCells = originalCells;
}
#Override
public void paint(Graphics g) {
for (int i = 0; i < vertical; i++) {
for (int j = 0; j < horizontal; j++) {
// Check cell value
if (newOriginalCells[j][i] == 1) {
g.setColor(Color.black);
} else {
g.setColor(Color.white);
}
// paint according to value
g.fillRect(j * 25, i * 25, 25, 25);
if (newOriginalCells[j][i] == 1) {
g.setColor(Color.white);
} else {
g.setColor(Color.black);
} // maybe change style?
g.drawRect(j * 25, i * 25, 25, 25);
}
}
}
}
I'm guessing, the problem is somewhere in newGeneration(), but other than that, I really have no idea anymore.

You have a common problem which I had myself a few months ago.
Java Swing GUI system works in thread called Event Dispatch Thread (EDT). This thread handle events like mouse clicks, typing etc. and paint the components to the screen. You should use this thread not as your main thread, but as sub-thread which working only once a certain time/when event happens, and not let him run continuously. In your code, since the user choose the cell to live, this thread run non-stop (because you started the program inside a listener, which is part of the EDT), and your GUI stuck, because it's updating only at the end of the thread.
You can solve this by using javax.swing.Timer. Timer is an object that allows you do tasks once a while, and it is perfect to this problem.
Use code like this:
ActionListener actionListaner = new ActionListener(){
public void actionPerformed(ActionEvent e){
//Put here you ne genration repeating code
}
};
int delay = 1000;//You delay between generations in millis
Timer timer = new timer(delay, actionListener);
The code in the actionPerformed method will repeat every second (or any other time you want it to repeat), and every operation of the timer will recall EDT instead of let it run non-stop.

Java: Fixing array "linking" to allow for resetting

Firstly, I know Lists are better in almost(if not all) every way. I have encountered a substantial bug in an encoder program that I am making. In this program, I have a button that resets the "wheels" responsible for encoding(One of the wheels rotates after every letter encoded). I have a final int[][] called wheelsOriginal that is supposed to store the original value of the int[][] called wheels. Both of these arrays are int[9][36]. I would like a way of making wheelsOriginal stay unchanged throughout the program instead of changing with wheels for some reason. Here is a good way to recreate the problem(Sorry for the lengthy intToChar and charToInt methods!):
Main class:
import java.awt.*;
import javax.swing.*;
public class mainClass {
public static void main(String[] args) {
JFrame frame = new JFrame("Encoder");
frame.setBackground(new Color(225,225,225));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Display d = new Display();
frame.add(d);
frame.pack();
frame.setResizable(false);
frame.setVisible(true);
}
}
Display class:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Display extends JPanel implements ActionListener {
static JButton button;
static JLabel letter;
static int currentKey = -10;
static int wheel = 0;
static int[][] wheels = {
{-3,10,-6,2,20,-7,22,5,23,4,6,-9,3,26,0,15,21,-2,13,14,12,1,17,11,-8,-5,18,8,24,9,25,7,19,16,-4,-1},
{9,22,14,12,18,-3,3,6,16,1,-7,25,24,19,-8,8,21,20,5,-6,-2,26,15,-9,23,10,11,0,-5,4,-4,2,17,-1,13,7},
{18,20,-9,15,12,-6,16,-4,-5,14,24,-7,-8,-3,-1,1,4,7,8,25,10,11,5,6,13,22,19,21,23,-2,3,26,17,9,0,2},
{-3,10,-6,2,20,-7,22,5,23,4,6,-9,3,26,0,15,21,-2,13,14,12,1,17,11,-8,-5,18,8,24,9,25,7,19,16,-4,-1},
{9,22,14,12,18,-3,3,6,16,1,-7,25,24,19,-8,8,21,20,5,-6,-2,26,15,-9,23,10,11,0,-5,4,-4,2,17,-1,13,7},
{25,18,5,8,7,-8,4,11,6,-7,26,21,-1,24,15,23,9,-6,-2,13,16,22,-5,10,17,3,1,-9,0,12,2,19,-4,14,20,-3},
{25,18,5,8,7,-8,4,11,6,-7,26,21,-1,24,15,23,9,-6,-2,13,16,22,-5,10,17,3,1,-9,0,12,2,19,-4,14,20,-3},
{25,18,5,8,7,-8,4,11,6,-7,26,21,-1,24,15,23,9,-6,-2,13,16,22,-5,10,17,3,1,-9,0,12,2,19,-4,14,20,-3},
{9,22,14,12,18,-3,3,6,16,1,-7,25,24,19,-8,8,21,20,5,-6,-2,26,15,-9,23,10,11,0,-5,4,-4,2,17,-1,13,7}
};
final static int[][] wheelsOriginal = wheels;
public Display() {
setPreferredSize(new Dimension(250,200));
setFocusable(true);
button = new JButton("Reset");
button.setPreferredSize(new Dimension(225,50));
button.setFont(new Font(button.getFont().getFontName(), button.getFont().getStyle(), 25));
letter = new JLabel(" ", SwingConstants.CENTER);
letter.setPreferredSize(new Dimension(225,100));
letter.setFont(new Font(letter.getFont().getFontName(), Font.BOLD, 125));
letter.setForeground(new Color(0,0,0));
addKeyListener(
new KeyListener() {
public void keyPressed(KeyEvent e) {
if(currentKey == -10 && e.getKeyCode() >= 65 && e.getKeyCode() <= 90) {
currentKey = e.getKeyCode() - 64;
letter.setText(encode() + "");
}
else if(currentKey == -10 && e.getKeyCode() >= 48 && e.getKeyCode() <= 57) {
currentKey = -1 * (e.getKeyCode() - 48);
letter.setText(encode() + "");
}
}
public void keyReleased(KeyEvent e) {
currentKey = -10;
letter.setText(" ");
}
public void keyTyped(KeyEvent e) {}
}
);
button.addActionListener(this);
add(button, TOP_ALIGNMENT);
add(letter);
}
public static char encode() {
int key = currentKey;
for(int i = 0; i < 9; i++) {
key = wheels[i][key + 9];
}
for(int i = 8; i >= 0; i--) {
key = wheels[i][key + 9];
}
rotate(wheels[wheel], isEven(wheel));
if(wheel < 8) {
wheel++;
}
else {
wheel = 0;
}
return((char) key);
}
public static int[] rotate(int[] wheel, boolean positive) {
int revolve;
if(positive) {
revolve = wheel[wheel.length - 1];
for(int i = wheel.length - 2; i > 0; i--) {
wheel[i + 1] = wheel[i];
}
wheel[0] = revolve;
}
else {
revolve = wheel[0];
for(int i = 1; i < wheel.length - 1; i++) {
wheel[i - 1] = wheel[i];
}
wheel[wheel.length - 1] = revolve;
}
return wheel;
}
public static boolean isEven(int num) {
return (num/2 == Math.abs(num/2));
}
public void actionPerformed(ActionEvent e) {
if(e.getSource().equals(button)) {
reset();
grabFocus();
}
}
public static void reset() {
for(int[] i : wheels) {
for(int x : i) {
System.out.print(x + " ");
}
System.out.println("");
}
System.out.println(" ");
for(int[] i : wheelsOriginal) {
for(int x : i) {
System.out.print(x + " ");
}
System.out.println("");
}
System.out.println(" ");
wheels = wheelsOriginal;
for(int[] i : wheels) {
for(int x : i) {
System.out.print(x + " ");
}
System.out.println("");
}
wheel = 0;
letter.setText(" ");
currentKey = ' ';
System.out.println("Pressed");
}
}
Whenever a key is pressed, the encoded letter appears in the window. Even pressing the same key over and over again will usually produce different letters. Pressing the reset button should reset the encoder so that pressing the letter 'A' three times should produce S, E, and Q in that order. I also have designed this so that whenever you press the reset button, three large bulks of numbers print in the console. These show the wheels array before reset, the wheelsOriginal array, and the product wheels array in that order. If you press keys and click reset several times, you will notice that wheelsOriginal changes with wheels. Please help...

Your problem is that you are creating wheelsOriginal as reference of wheels instead of copy. Thats why when you change wheels, wheelsOriginal changes as well.
final static int[][] wheelsOriginal = wheels;
Something like this loop can be used to create a copy of wheels
int[][] wheelsOriginal = new int[wheels.length][];
for( int i = 0; i < wheelsOriginal.length; i++ )
{
wheelsOriginal[i] = Arrays.copyOf( wheels[i], wheels[i].length );
}
Also, for your charToInt and IntToChar methods - you could use the fact that chars are numbers and a->z A->Z 0->9 are grouped together to shorten them significantly
I didn't test that - in case you decide to use something like this - think and test yourself
public int charToInt( char c )
{
if( c >= '0' && c <= '9' ) {
return '0' - c;
} else if( c >= 'A' && c <= 'Z' ) {
return c - 'A' + 1;
} else if( c >= 'a' && c <= 'z' ) {
return c - 'a' + 1;
} else {
return -10;
}
}
public char intToChar( int c )
{
if( c >= -9 && c <= 0 ){
return (char)('0' - c);
} else if( c >= 1 && c <= 26 ){
return (char)(c + 'A' - 1);
} else{
return ' ';
}
}

How to use JTextArea and Append

Please Help. When I run this GUI the numbers run off the frame. I know I have to use JTextArea and append but where do I put that in my code. can someone explain to me in simple terms and show me? I want to make it scroll vertically and horizontally and when I do add the JTextArea I get this error: error: cannot find symbol panel.setMessage(message);
import java.io.*;
import java.util.*;
import java.lang.*;
import java.text.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class prime extends JFrame
{
public static void main(String[] args)
{
prime frame = new prime();
}
private JTextArea panel;
private JPanel inPanel;
private JTextField inField;
public prime()
{
final int width = 500;
final int height = 500;
setSize(width, height);
setTitle("Find Prime Numbers");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
panel = new JTextArea(20, 10);
add(new JScrollPane(panel), "Center");
inPanel = new JPanel();
inPanel.add(new JLabel("Enter Your Number", SwingConstants.RIGHT));
inField = new JTextField(20);
ActionListener inListener = new TextListener();
inField.addActionListener(inListener);
inPanel.add(inField);
add(inPanel, "South");
setVisible(true);
}
private class TextListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
String message = inField.getText();
inField.setText("");
panel.setMessage(message);
}
}
class TextPanel extends JPanel
{
private String message;
private Color backGroundColor;
public TextPanel()
{
message = "";
backGroundColor = Color.white;
}
public TextPanel(String x, Color background)
{
message = x;
backGroundColor = background;
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
int width = getWidth();
int height = getHeight();
setBackground(backGroundColor);
g2.setColor(Color.black);
Font x = new Font("TimesNewRoman", Font.BOLD,20);
g2.setFont(x);
FontMetrics fm = g2.getFontMetrics(x);
g2.drawString(message,50, 50);
if(!(message.equals("")))
g2.drawString(previousPrime(message),50,78);
}
public void setMessage(String message) {
if (isPrime(Integer.parseInt(message))){
this.message = message + " is a prime number.";
}
else
this.message = message + " is not a prime number.";
repaint();
}
public boolean isPrime(int num){
for(int i = 2; i < num; i++){
if (num % i == 0)
return false;
}
if(num < 2)
return false;
return true;
}
public String previousPrime(String message){
String totalPrimeNum = "";
int finalNum = Integer.parseInt(message.substring(0,message.indexOf(" ")));
int count = 0;
for(int i = 2; i < finalNum; i++){
if(isPrime(i)) {
totalPrimeNum += " " + i;
count++;
}
if(count == 10) {
totalPrimeNum += "\n";
count = 0;
}
}
if (isPrime(Integer.parseInt(message.substring(0,message.indexOf(" ")))))
totalPrimeNum += " " + finalNum;
System.out.println(totalPrimeNum);
return totalPrimeNum;
}}}

Look at what you have and what you want to achieve. You have a method which can verify if a value is a prime or not, but it does not produce any output. You have a JTextArea which allows you to add content to it.
You have a square peg and a round hole. One of these things needs to change. You have control over the setMessage method, but you don't have control over the JTextArea, this would suggest that the setMessage needs to change. While you could pass the JTextArea to the setMessage method, a better solution would be to change the setMessage to return some kind of meaningful value or simply get rid of it in favor of using the isPrime method instead
Take your TestPane and move the functionality used to calculate and test for a prime number to a new class, for example...
public class PrimeCalculator {
public boolean isPrime(int num) {
for (int i = 2; i < num; i++) {
if (num % i == 0) {
return false;
}
}
if (num < 2) {
return false;
}
return true;
}
public String previousPrime(String message) {
StringBuilder totalPrimeNum = new StringBuilder(128);
int finalNum = Integer.parseInt(message.substring(0, message.indexOf(" ")));
int count = 0;
for (int i = 2; i < finalNum; i++) {
if (isPrime(i)) {
totalPrimeNum.append(" ").append(i);
count++;
}
if (count == 10) {
totalPrimeNum.append("\n");
count = 0;
}
}
if (isPrime(Integer.parseInt(message.substring(0, message.indexOf(" "))))) {
totalPrimeNum.append(" ").append(finalNum);
}
System.out.println(totalPrimeNum);
return totalPrimeNum.toString();
}
}
This now makes no assumptions over what you want to do and simply produces output. You can now use these methods and make decisions about how to use the output, for example...
private class TextListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent event) {
PrimeCalculator calc = new PrimeCalculator();
String message = inField.getText();
inField.setText("");
String text = message + " is not a prime number\n";
try {
if (calc.isPrime(Integer.parseInt(message))) {
text = message + " is a prime number\n";
}
} catch (NumberFormatException exp) {
text = message + " is not a valid integer\n";
}
panel.append(message);
panel.setCaretPosition(panel.getDocument().getLength());
}
}
Sometimes, you need to rethink your design to support what it is you want to achieve.
The process of verifying and calculating the prime numbers should do just that, they should not do anything else (like update the screen), this way you can decouple the code and re-use it in different ways which you didn't original think of (like outputting to a file or the web)
See How to Use Text Areas and How to Use Scroll Panes for more details

Updating JButton on a timer in a do-while loop

I'm having some trouble getting a JButton to update repeatedly (used with a timer) in a do-while loop. I'm working on a simple game, played on a 10 * 10 grid of tile objects which correspond to a JButton arrayList with 100 buttons.
This part of the program handles simple pathfinding (i.e. if I click on character, then an empty tile, the character will move through each tile on its way to the destination). There is a delay between each step so the user can see the character's progress.
In the current state of things, the movement is correct, but the JButton is only updated when the character reaches the destination, not on intermediate steps.
public void move(int terrainTile)
{
int currentPosition = actorList.get(selectedActor).getPosition();
int movementValue = 0;
int destination = terrainTile;
int destinationX = destination / 10;
int destinationY = destination % 10;
do
{
currentPosition = actorList.get(selectedActor).getPosition(); // Gets PC's current position (before move)
System.out.println("Old position is " + currentPosition);
int currentX = currentPosition / 10;
int currentY = currentPosition % 10;
if(actorList.get(selectedActor).getCurrentAP() > 0)
{
movementValue = 0;
if(destinationX > currentX)
{
movementValue += 10;
}
if(destinationX < currentX)
{
movementValue -= 10;
}
if(destinationY > currentY)
{
movementValue += 1;
}
if(destinationY < currentY)
{
movementValue -= 1;
}
int nextStep = currentPosition + movementValue;
myGame.setActorIdInTile(currentPosition, -1); //Changes ActorId in PC current tile back to -1
scrubTiles(currentPosition);
actorList.get(selectedActor).setPosition(nextStep); // Sets new position in actor object
System.out.println("Actor " + selectedActor + " " + actorList.get(selectedActor).getName() + " position has been updated to " + nextStep);
myGame.setActorIdInTile(nextStep, selectedActor); // Sets ActorId in moved to Tile
System.out.println("Tile " + nextStep + " actorId has been updated to " + selectedActor);
buttons.get(nextStep).setIcon(new ImageIcon(actorList.get(selectedActor).getImageName()));
// If orthagonal move AP-4
if(movementValue == 10 || movementValue == -10 || movementValue == 1 || movementValue == -1)
{
actorList.get(selectedActor).reduceAP(4);
}
// If diagonal move AP-6
else
{
actorList.get(selectedActor).reduceAP(6);
}
System.out.println(actorList.get(selectedActor).getName() + " has " + actorList.get(selectedActor).getCurrentAP() + " AP remaining");
try
{
Thread.sleep(500); // one second
}
catch (Exception e){}
buttons.get(nextStep).repaint();
}
else
{
System.out.println(actorList.get(selectedActor).getName() + " has insufficient AP to move");
break;
}
}while(destination != (currentPosition + movementValue));
What I've tried:
buttons.get(nextStep).repaint(); (Tried putting a command to repaint the button after setting the imageIcon. No change.
buttons.get(nextStep).revalidate(); (No 100% sure what this does - it came up as a potential solution, but doesn't work.
Steps 1 & 2 combined
Looked into the swing timer class - movement doesn't occur everytime an actionEvent is fired, (only if character is selected and target tile is empty) so not sure how I could get this to work
Any help would be greatly appreciated!

I really dont' know exactly what you wanted to know in your comments, though +1 to the answer above, seems to me that's the real cause. Have a look at this example program, simply add your call to the move(...) method inside the timerAction, seems like that can work for you. Here try this code :
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GridExample
{
private static final int SIZE = 36;
private JButton[] buttons;
private int presentPos;
private int desiredPos;
private Timer timer;
private Icon infoIcon =
UIManager.getIcon("OptionPane.informationIcon");
private ActionListener timerAction = new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
buttons[presentPos].setIcon(null);
if (desiredPos < presentPos)
{
presentPos--;
buttons[presentPos].setIcon(infoIcon);
}
else if (desiredPos > presentPos)
{
presentPos++;
buttons[presentPos].setIcon(infoIcon);
}
else if (desiredPos == presentPos)
{
timer.stop();
buttons[presentPos].setIcon(infoIcon);
}
}
};
public GridExample()
{
buttons = new JButton[SIZE];
presentPos = 0;
desiredPos = 0;
}
private void createAndDisplayGUI()
{
JFrame frame = new JFrame("Grid Game");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel contentPane = new JPanel();
contentPane.setLayout(new GridLayout(6, 6, 5, 5));
for (int i = 0; i < SIZE; i++)
{
final int counter = i;
buttons[i] = new JButton();
buttons[i].setActionCommand("" + i);
buttons[i].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
desiredPos = Integer.parseInt(
(String) buttons[counter].getActionCommand());
timer.start();
}
});
contentPane.add(buttons[i]);
}
buttons[presentPos].setIcon(infoIcon);
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
timer = new Timer(1000, timerAction);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new GridExample().createAndDisplayGUI();
}
});
}
}

This is because you are doing your do { } while in the UI thread. To solve this, you should use a SwingWorker, or a javax.swing.Timer

Java exception handling with multiple classes

I need to make the following exceptions: NoSuchRowException if the row is not between 1 and 3, IllegalSticksException if the number of sticks taken is not between 1 and 3, and NotEnoughSticksException if the number of sticks taken is between 1 and 3, but more than the number of sticks remaining in that row. My issue is I really don't understand the syntax. If someone could help me get started with one exception, I think I can figure the others out.
So far I have the main class:
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package nimapp;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**
*
* #author jrsullins
*/
public class NimApp extends JFrame implements ActionListener {
private static final int ROWS = 3;
private JTextField[] gameFields; // Where sticks for each row shown
private JTextField rowField; // Where player enters row to select
private JTextField sticksField; // Where player enters sticks to take
private JButton playButton; // Pressed to take sticks
private JButton AIButton; // Pressed to make AI's move
private NimGame nim;
public NimApp() {
// Build the fields for the game play
rowField = new JTextField(5);
sticksField = new JTextField(5);
playButton = new JButton("PLAYER");
AIButton = new JButton("COMPUTER");
playButton.addActionListener(this);
AIButton.addActionListener(this);
AIButton.setEnabled(false);
// Create the layout
JPanel mainPanel = new JPanel(new BorderLayout());
getContentPane().add(mainPanel);
JPanel sticksPanel = new JPanel(new GridLayout(3, 1));
mainPanel.add(sticksPanel, BorderLayout.EAST);
JPanel playPanel = new JPanel(new GridLayout(3, 2));
mainPanel.add(playPanel, BorderLayout.CENTER);
// Add the fields to the play panel
playPanel.add(new JLabel("Row: ", JLabel.RIGHT));
playPanel.add(rowField);
playPanel.add(new JLabel("Sticks: ", JLabel.RIGHT));
playPanel.add(sticksField);
playPanel.add(playButton);
playPanel.add(AIButton);
// Build the array of textfields to display the sticks
gameFields = new JTextField[ROWS];
for (int i = 0; i < ROWS; i++) {
gameFields[i] = new JTextField(10);
gameFields[i].setEditable(false);
sticksPanel.add(gameFields[i]);
}
setSize(350, 150);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
nim = new NimGame(new int[]{3, 5, 7});
draw();
}
// Utility function to redraw game
private void draw() {
for (int row = 0; row < ROWS; row++) {
String sticks = "";
for (int j = 0; j < nim.getRow(row); j++) {
sticks += "| ";
}
gameFields[row].setText(sticks);
}
rowField.setText("");
sticksField.setText("");
}
public void actionPerformed(ActionEvent e) {
// Player move
if (e.getSource() == playButton) {
// Get the row and number of sticks to take
int row = Integer.parseInt(rowField.getText())-1;
int sticks = Integer.parseInt(sticksField.getText());
// Play that move
nim.play(row, sticks);
// Redisplay the board and enable the AI button
draw();
playButton.setEnabled(false);
AIButton.setEnabled(true);
// Determine whether the game is over
if (nim.isOver()) {
JOptionPane.showMessageDialog(null, "You win!");
playButton.setEnabled(false);
}
}
// Computer move
if (e.getSource() == AIButton) {
// Determine computer move
nim.AIMove();
// Redraw board
draw();
AIButton.setEnabled(false);
playButton.setEnabled(true);
// Is the game over?
if (nim.isOver()) {
JOptionPane.showMessageDialog(null, "You win!");
playButton.setEnabled(false);
}
}
}
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
NimApp a = new NimApp();
}
}
The support class:
package nimapp;
import java.util.Random;
import javax.swing.JOptionPane;
import java.io.*;
import java.lang.*;
public class NimGame {
int x = 1;
int[] Sticks; //creating an array of sticks
int totalSticks = 0;
public NimGame(int[] initialSticks){
Sticks = initialSticks;}
public int getRow(int r){
return Sticks[r];}
public void play(int r, int s) throws IllegalSticksException {
try {
Sticks[r]=Sticks[r]-s;
if(s < 0 || s > 3)
throw new IllegalSticksException();
} catch (IllegalSticksException ex){
JOptionPane.showMessageDialog(null, "Not a valid row!");
} catch (IndexOutOfBoundsException e){
JOptionPane.showMessageDialog(null, "Too Many Sticks!");
}
}
public boolean isOver(){
int theTotal = 0;
for (int i = 0; i< Sticks.length; i++){
theTotal = Sticks[i];
System.out.println(Sticks[i]);
System.out.println(theTotal);
}
totalSticks = theTotal;
if (totalSticks <= 0){
return true;
}
else return false;
}
public void AIMove(){
Random randomInt = new Random ();
boolean tryRemove = true;
while(tryRemove && totalSticks >= 1){
int RandomRow = randomInt.nextInt(3);
if(Sticks[RandomRow] <= 0)//the computer can't remove from this row
continue;
//the max number to remove from row
int size = 3;
if( Sticks[RandomRow] < 3)//this row have least that 3 cards
size = Sticks[RandomRow];//make the max number to remove from the row be the number of cards on the row
int RandomDiscard = randomInt.nextInt(size) + 1;
Sticks[RandomRow] = Sticks[RandomRow] - RandomDiscard;
//I don't know if this is needed, but since we remove a RandomDiscard amount lest decrease the totalSticks
totalSticks = totalSticks - RandomDiscard;
//exit loop
tryRemove = false;
}
if(totalSticks <= 1){
int RandomRow = 0;
Sticks[RandomRow] = Sticks[RandomRow]-1;
isOver();
}
}
}

My issue is I really don't understand the syntax.
There is nothing wrong with the syntax as you have written it.
The problem is that you are catching the exception at the wrong place. You are (apparently) intending play to propagate the IllegalSticksException to its caller. But that won't happen because you are catching it within the play method.
There are two possible fixes depending on what you actually intent to happen.
You could remove the throws IllegalSticksException from the play signature.
You could remove the catch (IllegalSticksException ex){ ... } in play and catch/handle the exception at an outer level.