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How to Randomize Placement of a JLabel on a GridLayout of JButtons?

I am trying to make a chessboard, that will randomize the place of its pieces throughout the board.
Below is what I have so far
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
public class ChessBoard extends JFrame {
JLayeredPane layeredpane;
JPanel chessboard;
JButton[][] chessboardButtons;
Color black;
JLabel [][] chessboardLabels;
UIManager Ui;
ChessBoard() {
Dimension Size = new Dimension(600, 600);
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
pack();
setResizable(true);
setLocationRelativeTo(null);
setVisible(true);
setSize(600, 600);
setTitle("Chess Board");
layeredpane = new JLayeredPane();
getContentPane().add(layeredpane);
layeredpane.setPreferredSize(Size);
chessboard = new JPanel();
layeredpane.add(chessboard, JLayeredPane.DEFAULT_LAYER);
chessboard.setLayout(new GridLayout(8, 8));
chessboard.setPreferredSize(Size);
chessboard.setBounds(0, 0, Size.width, Size.height);
Ui = new UIManager();
chessboardButtons = new JButton[8][8];
black = Color.black;
ButtonHandler handler = new ButtonHandler();
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
chessboardButtons[i][j] = new JButton();
chessboardButtons[i][j].setBorderPainted(false);
if ((i + j) % 2 != 0) {
chessboardButtons[i][j].setBackground(black);
chessboardButtons[i][j].setOpaque(true);
}
chessboard.add(chessboardButtons[i][j]);
chessboardButtons[i][j].addActionListener(handler);
}
}
chessboardLabels = new JLabel[8][8];
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
chessboardLabels[i][j] = new JLabel();
chessboardLabels[i][j].setFont(new Font("Ariel", Font.BOLD, 20));
chessboardLabels[i][j].setText("H");
chessboardLabels[i][j].setHorizontalAlignment(JLabel.CENTER);
chessboardLabels[i][j].setVerticalAlignment(JLabel.CENTER);
chessboardLabels[i][j].setOpaque(true);
chessboardButtons[i][j].add(chessboardLabels[i][j]);
if(chessboardButtons[i][j].getBackground() == Color.black) {
chessboardLabels[i][j].setBackground(Color.black);
chessboardLabels[i][j].setForeground(Color.white);
}
}
}
}
private class ButtonHandler implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == chessboardButtons[0][0]) {
System.out.println("Button 0,0");
}
if (e.getSource() == chessboardButtons[0][1]) {
System.out.println("Button 0,1");
}
}
}
}
Right now I have the letter H filling all my buttons. What I need it to do is to:
limit the number of "H"'s there are on the board to be 32, 16 "White" and 16 "black" and
randomize the placement throughout the board.
Any ideas will be helpful!

I tried exactly this years ago, and I ran into several problems. One of the biggest is that dragging a piece from one square (JComponent) to another hard to do, because each JComponent has its bounds, and its Graphics clipping prevents you from drawing outside of these bounds. There are workarounds, like adding an Image to a higher level in the JLayeredPane, but this is still very hard to get right.
You really want to make you GUI a custom JComponent/JPanel that draws the whole board and can get mouse events across the whole board.
But before that, the right place to start is by creating a ChessModel that encapsulates the logic of the game. If you do that first and test it thoroughly, adding a GUI on top of that is easier than the other way around.
public class ChessModel {
char[][] board = new char[8][8];
...
public Point[] getPossibleMoves(Point pieceLocation) {
...
}
}

Create an ArrayList with 64 Integers numbered from 0 - 63
Use Collections.shuffle(...) to shuffle the numbers randomly
Take the first 16 values from the ArrayList and add white pieces to the board based on the integer value.
Take the next 16 values from the ArrayList and add the black pieces to the board.

First, I would start by decoupling parts of the system, this will provide you with a lot more flexibility.
For example, you want to decouple the "visual" from the "virtual". Components aren't managed in a "grid", instead, they are maintained in a list, so, you want some way you can quickly and easily ascertain the location of various components on the screen and how the relate to the "virtual" concept of the game or grid.
This is at the core concept of "model-view-controller", where the model represents a "grid" of "pieces" and the view is used to visually represent the model to the user. So you end up with a little bit of translation going on.
Now, you can do something like...
int row = (value / 8);
int col = (value % 8);
which, given a component index, will give you the row/col that they represent, but I'm also lazy 😉, so, I'm going to isolate the concept of a Piece...
public class Piece extends JPanel {
private JLabel label;
private Point cell;
public Piece(int index) {
setLayout(new GridBagLayout());
label = new JLabel(Integer.toString(index));
label.setForeground(Color.RED);
add(label);
setOpaque(false);
}
public void setCell(Point cell) {
this.cell = cell;
}
public Point getCell() {
return cell;
}
}
This does several things for me, first, it gives me a simple building block which can be used to represent a piece of data as well as maintain the "virtual" position of the piece, so I can easily look it up, independently.
It also divorces the piece from the board, which will make it easier to maintain (IMHO).
Next, I build the board...
setLayout(new GridLayout(8, 8));
int index = 0;
for (int row = 0; row < 8; row++) {
for (int col = 0; col < 8; col++) {
JPanel panel = new JPanel(new GridBagLayout()) {
#Override
public Dimension getPreferredSize() {
return new Dimension(50, 50);
}
};
// Indexed via x/y
cells[col][row] = panel;
if (index % 2 == 0) {
panel.setBackground(Color.WHITE);
} else {
panel.setBackground(Color.BLACK);
}
add(panel);
index++;
}
index++;
}
There's nothing really fancy here, it's just GridLayout with a bunch of color panels laid out on it.
The "fancy" part is the idea that, instead of using something complicated, like JLayeredPane, I'm simply going to add the Pieces directly to each cell.
Which leads us to the heart of the problem, how to randomise the position of the cells. Essentially, I'm going to create a list of numbers from 0 to 63 inclusive, randomise the list and then pop each number of off the list till I'm done.
Now, you could use an array, but filling an array with random numbers is not a simple task (especially if you want to guarantee uniqueness 😉)
// Fill a list of numbers
int totalCells = 8 * 8;
List<Integer> locations = new ArrayList<>(totalCells);
for (int value = 0; value < totalCells; value++) {
locations.add(value);
}
// Randomise the list
Collections.shuffle(locations);
// For al the white pieces, randomise their positions
for (index = 0; index < 16; index++) {
int value = locations.remove(0);
// Virtual coordinates
int row = (value / 8);
int col = (value % 8);
Point cell = new Point(col, row);
Piece piece = new Piece(index);
whitePieces[index] = piece;
piece.setCell(cell);
// Get the component offset by the value (physical)
JPanel cellPane = (JPanel) getComponent(value);
cellPane.add(piece);
}
// Now you can continue with the black pieces, just like above
// and because you've removed the "used" cell indexes from the
// list, you won't end up with duplicate positions
Now you're probably scratching your head over all this. But simply put, when you want to move a "piece", you simply remove it from it's current parent container, calculate the position ((row * 8) + col), get the new parent component (like above) and add it, simple.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Point;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Test extends JFrame {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JPanel[][] cells = new JPanel[8][8];
private Piece[] whitePieces = new Piece[16];
public TestPane() {
setLayout(new GridLayout(8, 8));
int index = 0;
for (int row = 0; row < 8; row++) {
for (int col = 0; col < 8; col++) {
JPanel panel = new JPanel(new GridBagLayout()) {
#Override
public Dimension getPreferredSize() {
return new Dimension(50, 50);
}
};
// Indexed via x/y
cells[col][row] = panel;
if (index % 2 == 0) {
panel.setBackground(Color.WHITE);
} else {
panel.setBackground(Color.BLACK);
}
add(panel);
index++;
}
index++;
}
int totalCells = 8 * 8;
List<Integer> locations = new ArrayList<>(totalCells);
for (int value = 0; value < totalCells; value++) {
locations.add(value);
}
Collections.shuffle(locations);
for (index = 0; index < 16; index++) {
int value = locations.remove(0);
int row = (value / 8);
int col = (value % 8);
Point cell = new Point(col, row);
Piece piece = new Piece(index);
whitePieces[index] = piece;
piece.setCell(cell);
JPanel cellPane = (JPanel) getComponent(value);
cellPane.add(piece);
}
}
}
public class Piece extends JPanel {
private JLabel label;
private Point cell;
public Piece(int index) {
setLayout(new GridBagLayout());
label = new JLabel(Integer.toString(index));
label.setForeground(Color.RED);
add(label);
setOpaque(false);
}
public void setCell(Point cell) {
this.cell = cell;
}
public Point getCell() {
return cell;
}
}
}
Oh, and just in case it's important, you can make use of component based drag-n-drop as well
How to make draggable components with ImageIcon
JLayeredPanel layout manager free moving objects
But, needs drives wants 😉

Scrolling through a JPanel within a JScrollingPanel

I'm trying to make a level editor for my platformer game, I want my levels to be 100 by 100 squares.
So far the editor works, but I can't scroll through the JPanel. I've been playing around and I've made a small test class to fiddle with which I'll post. If you run it, all it does it show the grid. However if I swap out two variables (I'll comment where) it can show an image and scroll according to the size of that image.
I want that scrolling ability only for the JPanel, so that I can scroll through my 100 x 100 square level.
import java.awt.BorderLayout;
public class ScrollPaneJ extends JFrame {
// setting the panels
private JPanel contentPane;
private JScrollPane scrollPane;
// dimensions/ variables of the grid
int size = 16;
int startX = 112;
int startY = 48;
int width = 30;
int height = 30;
// this is the grid
String[][] grid = new String[width][height];
// this is from the full editor class
String currentImage = new String("platform");
ImageIcon currentBackIcon = new ImageIcon("Resources/backdirttile.jpg");
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
// adding the scrollpane
ScrollPaneJ frame = new ScrollPaneJ();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public ScrollPaneJ() {
setTitle("Scrolling Pane Application");
setSize(new Dimension(300, 200));
setBackground(Color.gray);
setDefaultCloseOperation(EXIT_ON_CLOSE);
// defining the top and bottom panels, bottom is what I think I'm
// drawing on, top is where the scrollpanel goes, I copied this code
// from the internet and I'm not too sure how it works
JPanel topPanel = new JPanel();
JPanel bottomPanel = new JPanel(new GridLayout());
bottomPanel.setLayout(new BorderLayout());
getContentPane().add(bottomPanel);
topPanel.setLayout(new BorderLayout());
getContentPane().add(topPanel);
// this is the label I was talking about
Icon image = new ImageIcon("src/MenuDesign.jpg");
JLabel label = new JLabel(image);
// Create a tabbed pane
// if you set it to say label instead of bottomPanel, you can scroll
// through the size of the label
scrollPane = new JScrollPane(bottomPanel);
scrollPane.setBounds(40, 40, 100, 100);
// set it label here as well.
scrollPane.getViewport().add(bottomPanel);
// I was hoping this would force the scrollbar in but it does nothing
scrollPane
.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
scrollPane
.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
scrollPane.setBounds(50, 30, 300, 50);
JPanel contentPane = new JPanel(null);
contentPane.setPreferredSize(new Dimension(500, 400));
contentPane.add(scrollPane);
topPanel.add(scrollPane, BorderLayout.CENTER);
init();
}
public void init() {
// this sets the grid to empty
for (int x = 0; x < width; x++) {
for (int y = 0; y < height; y++) {
grid[x][y] = "";
}
}
}
#Override
public void paint(Graphics g) {
// this paints the grid
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.black);
for (int x = 0; x < width; x++) {
for (int y = 0; y < height; y++) {
g2d.drawRect(x * size + startX, y * size + startY, size, size);
if (grid[x][y].equals("")) {
g2d.drawImage(currentBackIcon.getImage(),
x * size + startX, y * size + startY, null);
}
g2d.setColor(Color.black);
g2d.drawRect((x * size) + 1 + startX, (y * size) + 1 + startY,
size, size);
}
}
}
public void drawTile() {
// this isn't enabled which is why you can't paint the grid, however it
// would change the tile of the square you're mouse is on, to the
// current tile, it works and isn't really important for what i need
// help with
PointerInfo a = MouseInfo.getPointerInfo();
Point b = a.getLocation();
int mouseX = (int) b.getX();
int mouseY = (int) b.getY();
int gMX = ((mouseX - 48) / 16) - 4;
int gMY = ((mouseY - 48) / 16) - 3;
grid[gMX][gMY] = currentImage;
repaint();
}
}

scrollPane.getViewport().add(bottomPanel); should be more like scrollPane.getViewportView(bottomPanel);
You shouldn't be painting directly to the frame, as child components can be painted without the notification to the parents, meaning that what ever you've painted could be partially wiped out. Instead, this kind of painting should be done within a custom component which acts as the JScrollPane's, JViewport's view.
A JScrollPane needs two things, first, the size that the component would like to be (the preferredSize) and the size of the viewport view. If the component doesn't implement the Scrollable interface, then the component's preferredSize is used to determine that as well. This is why a JLabel will work.
A JScrollPane has a JViewport as it's primary child component. The JViewport should only have a single component, typically assigned either via JScrollPane#setViewportView or JViewport#setView methods
See How to Use Scroll Panes for more details
Create a custom component that extends JPanel and override it's getPreferredSize method to return the size of the component you want. Override it's paintComponent method and perform you custom painting their.
Overlaying custom painting ontop of other components is more difficult

You can also add JScrollPane in your panel like this
JPanel p = new JPanel();
add(new JScrollPane(p));

How to add parts of an image to an ArrayList - Java

For homework I am trying to add a sprite sheet to a 2D ArrayList for a simple card game. I want to be able to have it like you would in a normal 2D array only with the dynamic ability of the array list since I will have to remove cards that are already drawn.
I am using a number generator that will generate numbers between the first and last indexes (0 - 51) inclusive and it will show a card up on the screen when the user clicks the draw card button. Then it will allow another user or an AI to draw a card and it will determine who has the highest card and declare that person the winner of that round, remove both drawn cards and repeat the cycle until 26 turns have been surpassed then the program will tally up all round wins and the player with the most round wins wins the game overall.
My question is: How can I divide my one sprite sheet into 52 sections and add that to my ArrayList?
This is what I have so far. I know it doesn't work yet, but I'm not entirely sure if I'm on the right track.
//private ImageIcon[][] cards = new ImageIcon[4][13];
private BufferedImage img;
private final int _WIDTH = 74;
private final int _HEIGHT = 94;
public CardGame1(ImageIcon[][] cards){
try{
img = ImageIO.read(getClass().getResource(
"classic-playing-cards.png"));
}catch(Exception e){
e.printStackTrace();
}
for(int r = 0; r < cards.length; r++){
for(int c = 0; c < cards[r].length; c++){
cards[r][c] = new ImageIcon(img.getSubimage(c * _WIDTH,
r * _HEIGHT, _WIDTH, _HEIGHT));
}
}
}
Some one told me to put the ArrayList in another class so here it is:
private JFrame frame;
private JPanel panel;
private Random rand;
private JButton drawCard;
private JLabel card;
private ArrayList<ArrayList<CardGame1>> _cardObj
= new ArrayList<ArrayList<CardGame1>>();
public CardGameGUI(){
gameBoard();
}
public void gameBoard(){
frame = new JFrame("Card Game");
panel = new JPanel();
frame.setSize(600, 500);
frame.setLayout(new GridLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(true);
frame.setVisible(true);
frame.add(panel);
panel.setBackground(Color.GREEN);
drawCard = new JButton("Draw Card!");
drawCard.setSize(100, 50);
panel.add(drawCard);
drawCard.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent arg0) {
}
});
}

These links that should solve your problem
https://docs.oracle.com/javase/8/docs/api/java/awt/image/BufferedImage.html#copyData-java.awt.image.WritableRaster-
http://www.programcreek.com/java-api-examples/index.php?api=java.awt.image.WritableRaster

Custom JButton not sizing properly?

I am creating a matching game using Netbeans, but not the GUI editor (it sucks). So, basically, I created a new class, called Card, that extends the JButton class. Upon construction, the button's size is set to 100px by 100px and an icon is set. When I add the button to a JPanel in a GridBagLayout, it is not the intended size.
Here is some of my code:
JFRAME CLASS:
package matchinggame;
... imports ...
public class MatchingGameWindow extends JFrame {
Card[] cards = new Card[16]; //16 game cards
public MatchingGameWindow() {
...
//Create new game panel (for the cards)
JPanel gamePanel = new JPanel(new GridBagLayout());
//gamePanel.setSize(500,500); removed as it is not needed.
...
this.add(gamePanel, BorderLayout.CENTER);
//Create 16 card objects
cards = createCards();
//Create new grid bag constraints
GridBagConstraints gbc = new GridBagConstraints();
//Add the cards to the game panel
int i=0;
for (int y = 0; y < 4; y++) {
gbc.gridy = y;
for (int x = 0; x < 4; x++) {
gbc.gridx = x;
gamePanel.add(cards[i], gbc);
i++;
}
}
}
public final Card[] createCards() {
Card[] newCards = new Card[16];
//New choices array
ArrayList<Integer> choices = new ArrayList();
int[] choiceValues = {0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7};
//Add the initial choice values to the arraylist
for (int i=0; i < choiceValues.length; i++) {
choices.add(choiceValues[i]);
}
//Create 16 cards
for (int i=0; i < 16; i++) {
//Initial value of -1 for error checking
int iconIndex = -1;
//Loop until card is created
while (iconIndex == -1) {
//Get a random number from 0 - 7
Random r = new Random();
int rInt = r.nextInt(8);
//If the random number is one of the choices
if (choices.contains(rInt)) {
//the icon # will be the random number
iconIndex = rInt;
//Get rid of that choice (it is used up)
choices.remove(new Integer(rInt));
//Create a new Card in the Card[]
newCards[i] = new Card(i,iconIndex);
//If all the choices are gone
} else if (choices.isEmpty()){
iconIndex = -1; //done creating this card (breaks out of loop)
}
}
}
//Return the created cards
return newCards;
}
}
CARD CLASS:
package matchinggame;
import javax.swing.ImageIcon;
import javax.swing.JButton;
public class Card extends JButton {
final static ImageIcon defaultIcon = new ImageIcon("cardback.jpg");
ImageIcon secretIcon;
boolean isRevealed = false;
...
public Card(final int cardIndex, int secretIconIndex) {
//Size is 100px by 100px
setSize(100, 100);
//Default icon is card back image
setIcon(defaultIcon);
//Get the secret icon behind the back of the card
secretIcon = icons[secretIconIndex];
}
}
And using this code I get a result of this:
Any ideas as to what I am doing wrong here?
EDIT:
I overrided the getPreferredSize method like Hovercraft Full Of Eels said, and it worked!
I added this code in the Card class:
#Override
public Dimension getPreferredSize() {
return new Dimension(100,100);
}
and got my desired result:
Now I must be doing something wrong with the icons, as they are not showing up as they should.

You should not use setSize(...) in the class's constructor but rather override the class's getPreferredSize() method to return a Dimension(100, 100). And in fact you should have setSize(...) no-where in your program. Instead use decent layout managers, call pack() on the JFrame after adding all components and before setting it visible, and let the layout managers size the GUI appropriately.

Java - Swing GUI renders incorrectly in Windows 7

I'm building a Tic Tac Toe game in Java with a Swing GUI, and it renders correctly in Ubuntu 10.4 and Windows XP. This is how it looks like in Ubuntu:
When I copied the bin-folder with all the class files and tried to run the program in Windows 7 it looked like this instead:
I just can't understand what's wrong. As I said, it works perfectly in Ubuntu 10.4 and Windows XP.
I would be very happy if someone could help me out! I'll post the code related to the GUI, just in case it is needed to solve the problem.
Here is the code I use to initialize the GUI:
//Initializing GUI.
frame = new JFrame(); //Creating the window.
frame.setTitle("Tic Tac Toe"); //Setting the title of the window.
frame.addMouseListener(this);
frame.getContentPane().add(BorderLayout.CENTER, grid.getPanel()); //Adding the grid panel.
info = new JLabel(" Initializing game..."); //Creating info text.
frame.getContentPane().add(BorderLayout.SOUTH, info); //Adding info text.
//Setting GUI properties.
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(300, 300);
frame.setVisible(true);
The panel with the grid itself is created in my GameGrid class, which have a method "JPanel getPanel()". Here is the initialization of that panel (the code belongs in the constructor of GameGrid):
GridBox temp;
layout = new GridLayout(getHeight(), getWidth());
panel = new JPanel(layout);
panel.setBorder(
BorderFactory.createCompoundBorder(
BorderFactory.createTitledBorder("Click in a box to place a marker:"),
BorderFactory.createEmptyBorder(5,5,5,5)));
//Creating a GridBox for each cell, and adding them to the panel in the right order..
for(int i = 0; i < getHeight(); i++) {
for(int j = 0; j < getWidth(); j++) {
temp = new GridBox(j, i);
temp.addMouseListener(listener);
panel.add(temp);
}
}
GridBox is a subclass of JPanel, which I modified to automatically show the contents of the grid at the coordinates specified.
class GridBox extends JPanel {
private static final long serialVersionUID = 1L;
int fontsize, x, y, value, signHeight, signWidth;
char print;
FontMetrics fm;
LineMetrics lm;
public GridBox(int a, int b) {
x = a; //TODO - input control
y = b;
}
public Move getMove() {
Move m = new Move(x, y);
return m;
}
public void paintComponent(Graphics g) {
Border blackline = BorderFactory.createLineBorder(Color.black);
setBorder(blackline);
Dimension size = getSize();
Rectangle2D rect;
fontsize = (int)(size.getHeight()*0.75);
value = getGridValue(x, y);
if(value == EMPTY)
print = ' ';
else if(value == 0)
print = 'X';
else if(value == 1)
print = 'O';
else
print = (char)value;
Font font = new Font("Times New Roman", Font.PLAIN, fontsize);
g.setFont(font);
fm = g.getFontMetrics();
rect = fm.getStringBounds(Character.toString(print), g);
signHeight = (int)rect.getHeight();
signWidth = (int)rect.getWidth();
g.setColor(Color.black);
g.drawString(Character.toString(print), (size.width/2)-(signWidth/2), (size.height/2)-(signHeight/2)+fm.getAscent());
}
}
Thanks in advance!

There's an obvious problem in the you change the border whilst repainting the component. That's going to cause all sorts of problems.

Also, I don't see where you paint the background of the panel. You should have
super.paintComponent(g);
at the top of the method.