Develop Reference

JButtons not showing up after initialisation [Java Swing]

I know there are super many questions here on stack overflow about JElements not showing up, all because someone forgot to add a setVisible(true) at the end of the constructor. But at least I belive my problem is something different. I am currently creating a chess-game for college, and for that I have the
Game class: here it all comes together
the abstract Piece class extending JButton in package Pieces
and a class for Each Piece (Rook, Bishop, ...) each extending Piece and being located in the Pieces package
before I write much more and it is a dumb error again, here the code:
import javax.swing.*;
import Pieces.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Game extends JFrame {
private static final int width = 8;
private static final int height = 8;
private static Piece clicked;
private static Piece[][] fields = new Piece[width][height];
private JPanel main = new JPanel();
public static void init(JPanel g) {
for (int y = 0; y < fields.length; y++) {
for (int x = 0; x < fields[y].length; x++) {
if (y == 1) fields[y][x] = new Pawn(x, y, true); //2nd or 7th row is filled with pawns
else if (y == 6) fields[y][x] = new Pawn(x, y, false);
else {
fields[y][x] = new Empty(x,y,true);
}
fields[y][x].addActionListener(e -> {
var p = (Piece) e.getSource();
System.out.println(p.getX() + p.getY());
});
g.add(fields[y][x]);
}
}
}
public Game() {
main.setBackground(Color.blue.darker());
main.setLayout(new GridLayout(8,8));
this.setSize(800,800);
init(main);
this.add(main);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.setVisible(true);
}
public static void main(String[] args) {
var g = new Game();
}
}
package Pieces;
import javax.swing.*;
public abstract class Piece extends JButton {
private int x;
private int y;
private final boolean isWhite;
public Piece(int x, int y, boolean isWhite) {
this.x = x;
this.y = y;
this.isWhite = isWhite;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
public boolean isWhite() {
return isWhite;
}
public boolean canMoveTo(int toX, int toY) {
return true;
}
}
each Piece-extending class is setup exactly like this:
package Pieces;
import java.awt.*;
public class Pawn extends Piece{
public Pawn(int x, int y, boolean isWhite) {
super(x, y, isWhite);
this.setText(isWhite ? "Pawn" : "pawn");
}
}
Expected behavior:
open a window with 64 JButtons in it, displaying the name of the Piece they represent (there is indeed an Empty-class for non-used fields)
Actual behavior:
opens a window with one button at the top left but first when I go over the fields with my cursor the buttons start appearing
state 1: state 1
state 2: state 2

You can't override getX and getY like this, these properties are used by the layout managers to layout the components.
Instead, maybe make use of Point to store the virtual or "cell" position
public static abstract class Piece extends JButton {
private final boolean isWhite;
private Point cell;
public Piece(int x, int y, boolean isWhite) {
cell = new Point(x, y);
this.isWhite = isWhite;
}
public Point getCell() {
return cell;
}
public boolean isWhite() {
return isWhite;
}
public boolean canMoveTo(int toX, int toY) {
return true;
}
}
Runnable example...
import java.awt.Color;
import java.awt.EventQueue;
import javax.swing.JFrame;
import java.awt.GridLayout;
import java.awt.Point;
import javax.swing.JButton;
import javax.swing.JPanel;
public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.add(new BoardPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class BoardPane extends JPanel {
private static final int width = 8;
private static final int height = 8;
private Piece clicked;
private Piece[][] fields = new Piece[width][height];
public BoardPane() {
setBackground(Color.blue.darker());
setLayout(new GridLayout(8, 8));
buildBoard();
}
protected void buildBoard() {
for (int y = 0; y < fields.length; y++) {
for (int x = 0; x < fields[y].length; x++) {
if (y == 1) {
fields[y][x] = new Pawn(x, y, true); //2nd or 7th row is filled with pawns
} else if (y == 6) {
fields[y][x] = new Pawn(x, y, false);
} else {
fields[y][x] = new Empty(x,y,true);
}
fields[y][x].addActionListener(e -> {
var p = (Piece) e.getSource();
System.out.println(p.getCell());
});
add(fields[y][x]);
}
}
}
}
public static abstract class Piece extends JButton {
private final boolean isWhite;
private Point cell;
public Piece(int x, int y, boolean isWhite) {
cell = new Point(x, y);
this.isWhite = isWhite;
}
public Point getCell() {
return cell;
}
public boolean isWhite() {
return isWhite;
}
public boolean canMoveTo(int toX, int toY) {
return true;
}
}
public static class Pawn extends Piece {
public Pawn(int x, int y, boolean isWhite) {
super(x, y, isWhite);
this.setText(isWhite ? "Pawn" : "pawn");
}
}
public static class Empty extends Piece {
public Empty(int x, int y, boolean isWhite) {
super(x, y, isWhite);
this.setText("X");
}
}
}

How do I change the rectangles to an image?

I just started learning Java (OOP) and I am trying to develop a simple game (like space invaders). I want to replace the guards (brown rectangles) to an image to make the game more aesthetically pleasing.
I am not sure how to do this as the guards are dependent on a lot of things. I tried using the loadImage() method and others but it did not work.
Relevant codes:
Guard.java
public class Guard {
private List<Square> squares;
public Guard(int x, int y) {
squares=new ArrayList<>();
for(int i=0; i<3; i++) {
for (int j = 0; j < 6; j++) {
squares.add(new Square(x + SQUARE_SIZE * j, y + SQUARE_SIZE * i));
}
}
}
public void collisionWith(MovingObject obj) {
for(Square square : squares) {
if(square.visible && square.intersects(obj.getBoundary())) {
square.setVisible(false);
obj.die();
}
}
}
public void draw(Graphics g) {
for(Square square : squares)
{
if(square.visible) square.draw(g);
}
}
}
Square.java
class Square extends Rectangle {
boolean visible;
Square(int x, int y)
{
super(x, y, SQUARE_SIZE, SQUARE_SIZE);
setVisible(true);
}
void setVisible(boolean visible) {
this.visible = visible;
}
void draw(Graphics g) {
g.setColor(new Color(228, 155, 30));
g.fillRect(x, y, width, height);
}
}
Screenshot for reference: Instead of brown boxes, I want to change it to other things using images

The following mre demonstrates using an image to represent a rectangle. Note that for easier implementation Gurd extends Componenet:
import java.awt.*;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
public class SwingMain {
SwingMain() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.add(new Guard(0,0));
frame.pack();
frame.setVisible(true);
}
class Guard extends Component{
private static final int GAP = 3, W = 6, H = 3;
private int squareSize, totalX, totalY;
private final List<Square> squares;
public Guard(int x, int y) {
squares=new ArrayList<>();
totalY = 0;
Square square = null;
for(int i=0; i< H; i++) {
totalX = 0;
for (int j = 0; j < W; j++) {
square = new Square(x + totalX , y + totalY );
squares.add(square);
totalX += square.getWidth() +GAP;
}
totalY += square.getHeight() +GAP;
}
}
#Override
public void paint(Graphics g) {
super.paint(g);
for(Square square : squares) {
square.draw(g);
}
}
#Override
public Dimension getPreferredSize(){
return new Dimension(totalX, totalY);
}
}
class Square{
private static final String BOX =
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/128x128/Box_Orange.png";
private Image image = null;
private final int x,y;
Square(int x, int y) {
this.x=x; this.y = y;
try {
image = new ImageIcon(new URL(BOX)).getImage();
} catch (IOException ex) {
ex.printStackTrace();
}
}
void draw(Graphics g) {
g.drawImage(image, x,y, null);
}
int getWidth(){
return image.getWidth(null);
}
int getHeight(){
return image.getHeight(null);
}
}
public static void main(String[] args) {
new SwingMain();
}
}
Square is not efficient because it reads and constructs image over again. To make it more efficient you can introduce a static block to initialize image only once:
static class Square{
private static final String BOX =
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/128x128/Box_Orange.png";
private static Image image = null;
static{
try {
image = new ImageIcon(new URL(BOX)).getImage();
} catch (IOException ex) {
ex.printStackTrace();
}
}
private final int x,y;
Square(int x, int y) {
this.x=x; this.y = y;
}
void draw(Graphics g) {
g.drawImage(image, x,y, null);
}
int getWidth(){
return image.getWidth(null);
}
int getHeight(){
return image.getHeight(null);
}
}

Isometric tiles drawing and picking - JAVA

I'm trying to draw isometric tiles in Java and implement a tile picking system using the mouse cursor. I draw the tiles using these math formulas I found and adapted to my tile textures which you can find below. Tiles are 64x64px but flat tiles are only 32px height even if I draw them using the 64x64 sprite.
The map is a simple 2d array where my tiles are represented by their id.
Here is the class I use to convert map coordinates to screen coordinates using the toIso() function. I pass my screen coordinates which represent the cursor position on the screen to the toGrid() function to convert them to map coordinates.
public class Utils {
private static int TILE_WIDTH = Tile.TILE_WIDTH;
private static int TILE_HEIGHT = Tile.TILE_HEIGHT;
private static int TILE_WIDTH_HALF = TILE_WIDTH/2;
private static int TILE_HEIGHT_HALF = TILE_HEIGHT/2;
private static int TILE_WIDTH_QUARTER = TILE_WIDTH_HALF/2;
private static int TILE_HEIGHT_QUARTER = TILE_HEIGHT_HALF/2;
public static int[] toIso(int x, int y){
int i = (x - y) * TILE_WIDTH_HALF;
int j = (x + y) * TILE_HEIGHT_QUARTER;
//800 and 100 are temporary offsets I apply to center the map.
i+=800;
j+=100;
return new int[]{i,j};
}
public static int[] toGrid(int x, int y){
//800 and 100 are temporary offsets I apply to center the map.
x-=800;
y-=100;
int i = ( x / ( TILE_WIDTH_HALF ) + y / ( TILE_HEIGHT_QUARTER )) / 2;
int j = ( y / ( TILE_HEIGHT_QUARTER ) - ( x / ( TILE_WIDTH_HALF ))) / 2;
return new int[]{i,j};
}}
I currently render my tiles by using two for loops and converting the map coordinates to screen coordinates using the toIso() function.
public void render(Graphics g){
for(int x = 0;x<width;x++){
for(int y = 0;y<height;y++){
int[] isoCoords = Utils.toIso(x, y);
int fx = isoCoords[0];//
int fy = isoCoords[1];//
if(world[x][y] == 0){
Tile grass = new GrassTile(0);
grass.render(g, grass.getId(), fx, fy);
}else if(world[x][y] == 1){
Tile water = new WaterTile(1);
water.render(g, water.getId(), fx, fy);
}
}
}
}
I get a diamond shape as I wanted rendered on the screen.
I finally update each tick which are the actual mouse coordinates on screen.
int[] coords = Utils.toGrid(mouseManager.getMouseX(), mouseManager.getMouseY());
tileX = coords[0];
tileY = coords[1];
The selected tile is finally rendered:
BufferedImage selectedTexture = Assets.selected;
int[] coordsIsoSelected = Utils.toIso(this.tileX, this.tileY);
g.drawImage(selectedTexture, coordsIsoSelected[0], coordsIsoSelected[1], Tile.TILE_WIDTH, Tile.TILE_HEIGHT, null);
g.drawRect(Utils.toIso(tileX, tileY)[0], Utils.toIso(tileX, tileY)[1]+Tile.TILE_HEIGHT/2, Tile.TILE_WIDTH, Tile.TILE_HEIGHT/2);//I draw a rectangle to visualize what's happening.
Finally, my tile detection isn't working as expected, it isn't fitting the tiles perfectly, however it seems to be in relation with the rectangle I draw. I can't figure out the solution to this problem, I thank you in advance for reading or any advice you could give to me. If you need more precisions, I would be glad to give you more informations.
Here is a video showing what is actually happening: youtu.be/baCVIfJz2Wo
EDIT:
Here is some of my code you could use to run an application like mine. Sorry for this very messy code, but I tried to make it as short as possible without disturbing the behavior of the "game".
You will need to put the sheet provided before into a "textures" folder created into the ressource folder of the project.
The gfx package:
package fr.romainimberti.isometric.gfx;
import java.awt.image.BufferedImage;
public class Assets {
private static final int width = 64, height = 64;
public static BufferedImage grass, water, selected;
public static void init(){
//Temp
SpriteSheet tileSheet = new SpriteSheet(ImageLoader.loadImage("/textures/sheet.png"));
grass = tileSheet.crop(width*2, 0, width, height);
water = tileSheet.crop(width*9, height*5, width, height);
selected = tileSheet.crop(0, height*5, width, height);
//
}
}
package fr.romainimberti.isometric.gfx;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
public class ImageLoader {
public static BufferedImage loadImage(String path){
try {
return ImageIO.read(ImageLoader.class.getResource(path));
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
return null;
}
}
package fr.romainimberti.isometric.gfx;
import java.awt.image.BufferedImage;
public class SpriteSheet {
private BufferedImage sheet;
public SpriteSheet(BufferedImage sheet){
this.sheet = sheet;
}
public BufferedImage crop(int x, int y, int width, int height){
return sheet.getSubimage(x, y, width, height);
}
}
The rest of the project:
package fr.romainimberti.isometric;
public class Launcher {
public static void main(String args[]){
System.setProperty("sun.awt.noerasebackground", "true");
Game game = new Game("Isometric", 1280, 720);
game.start();
}
}
package fr.romainimberti.isometric;
import java.awt.Canvas;
import java.awt.Dimension;
import javax.swing.JFrame;
public class Display {
private JFrame frame;
private Canvas canvas;
private String title;
private int width, height;
public Display(String title, int width, int height){
this.title = title;
this.width = width;
this.height = height;
createDisplay();
}
private void createDisplay(){
frame = new JFrame(title);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(true);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
canvas = new Canvas();
canvas.setPreferredSize(new Dimension(width, height));
canvas.setMaximumSize(new Dimension(width, height));
canvas.setMinimumSize(new Dimension(width, height));
canvas.setFocusable(true);
frame.add(canvas);
frame.pack();
}
public Canvas getCanvas(){
return canvas;
}
public JFrame getFrame(){
return frame;
}
}
package fr.romainimberti.isometric;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import java.util.concurrent.ThreadLocalRandom;
import javax.swing.JFrame;
import fr.romainimberti.isometric.gfx.Assets;
public class Game implements Runnable {
private Display display;
private int width, height;
public JFrame frame;
private boolean running = false;
private Thread thread;
public String title;
private BufferStrategy bs;
private Graphics g;
public int x, y;
public int[][] world;
public static final int TILE_WIDTH = 64;
public static final int TILE_HEIGHT = 64;
public static final int TILE_WIDTH_HALF = 32;
public static final int TILE_HEIGHT_HALF = 32;
public static final int TILE_WIDTH_QUARTER = 16;
public static final int TILE_HEIGHT_QUARTER = 16;
public int xOffset;
//Input
private MouseManager mouseManager;
public Game(String title, int width, int height){
this.width = width;
this.height = height;
this.mouseManager = new MouseManager(this);
this.world = new int[10][10];
}
private void init(){
display = new Display(title, width, height);
display.getFrame().addMouseListener(mouseManager);
display.getFrame().addMouseMotionListener(mouseManager);
display.getCanvas().addMouseListener(mouseManager);
display.getCanvas().addMouseMotionListener(mouseManager);
this.frame = display.getFrame();
Assets.init();
xOffset = frame.getWidth()/2;
//Fill the world
for(int i = 0;i<world.length;i++){
for(int j=0;j<world[0].length;j++){
int r = ThreadLocalRandom.current().nextInt(0,1+1);
if(r == 0)
world[i][j] = 0;
else
world[i][j] = 1;
}
}
}
private void tick(){
mouseManager.tick();
xOffset = frame.getWidth()/2;
}
private void render(){
bs = display.getCanvas().getBufferStrategy();
if(bs == null){
display.getCanvas().createBufferStrategy(3);
return;
}
g = bs.getDrawGraphics();
//Clear Screen
g.clearRect(0, 0, frame.getWidth(), frame.getHeight());
//Draw Here
//World render
for(int x = 0;x<world.length;x++){
for(int y = 0;y<world[0].length;y++){
int[] isoCoords = toIso(x, y);
int fx = isoCoords[0];//
int fy = isoCoords[1];//
if(world[x][y] == 0){
g.drawImage(Assets.grass, fx, fy, null);
}else if(world[x][y] == 1){
g.drawImage(Assets.water, fx, fy, null);
}
}
}
//Selected tile render
int[] coordsIsoSelected = toIso(x, y);
g.drawImage(Assets.selected, coordsIsoSelected[0], coordsIsoSelected[1], TILE_WIDTH, TILE_HEIGHT, null);
//End Drawing
bs.show();
g.dispose();
}
public void run(){
init();
int fps = 120;
double timePerTick = 1000000000 / fps;
double delta = 0;
long now;
long lastTime = System.nanoTime();
while(running){
now = System.nanoTime();
delta += (now - lastTime) / timePerTick;
lastTime = now;
if(delta >= 1){
tick();
render();
delta--;
}
}
stop();
}
public MouseManager getMouseManager(){
return mouseManager;
}
public int getWidth(){
return width;
}
public int getHeight(){
return height;
}
public synchronized void start(){
if(running)
return;
running = true;
thread = new Thread(this);
thread.start();
}
public synchronized void stop(){
if(!running)
return;
running = false;
try {
thread.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public static int[] toIso(int x, int y){
int i = (x - y) * TILE_WIDTH_HALF;
int j = (x + y) * TILE_HEIGHT_QUARTER;
i+=xOffset;
return new int[]{i,j};
}
public static int[] toGrid(int x, int y){
x-=xOffset;
int i = ( x / ( TILE_WIDTH_HALF ) + y / ( TILE_HEIGHT_QUARTER )) / 2;
int j = ( y / ( TILE_HEIGHT_QUARTER ) - ( x / ( TILE_WIDTH_HALF ))) / 2;
return new int[]{i,j};
}
}
package fr.romainimberti.isometric;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
public class MouseManager implements MouseListener, MouseMotionListener {
private boolean leftPressed, rightPressed;
private int mouseX, mouseY;
private Game game;
public MouseManager(Game game){
this.game = game;
}
public void tick(){
game.x = game.toGrid(mouseX, mouseY)[0];
game.y = game.toGrid(mouseX, mouseY)[1];
}
// Getters
public boolean isLeftPressed(){
return leftPressed;
}
public boolean isRightPressed(){
return rightPressed;
}
public int getMouseX(){
return mouseX;
}
public int getMouseY(){
return mouseY;
}
// Implemented methods
#Override
public void mousePressed(MouseEvent e) {
if(e.getButton() == MouseEvent.BUTTON1)
leftPressed = true;
else if(e.getButton() == MouseEvent.BUTTON3)
rightPressed = true;
}
#Override
public void mouseReleased(MouseEvent e) {
if(e.getButton() == MouseEvent.BUTTON1)
leftPressed = false;
else if(e.getButton() == MouseEvent.BUTTON3)
rightPressed = false;
}
#Override
public void mouseMoved(MouseEvent e) {
mouseX = e.getX();
mouseY = e.getY();
}
#Override
public void mouseDragged(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseClicked(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
}
If you need it, you can find here my project architecture so you can organize all the files correctly.
Again, sorry for this very, very messy code but I had to split all the usefull parts of my game to reduce it's size. Also don't forget to download and place correctly the sheet file. Hope this will help.
128*64 tiles

just wanted to say that I finally solved it. It was just a conversion to int issue. These are the final methods that I use. Hope it will help people who are trying to work with isometric tiles. Thank you !
public static int[] toIso(int x, int y){
int i = (x - y) * TILE_WIDTH_HALF;
int j = (x + y) * TILE_HEIGHT_QUARTER;
i += xOffset-TILE_WIDTH_HALF;
j+=yOffset;
return new int[]{i,j};
}
public static int[] toGrid(double i, double j){
i-=xOffset;
j-=yOffset;
double tx = Math.ceil(((i / TILE_WIDTH_HALF) + (j / TILE_HEIGHT_QUARTER))/2);
double ty = Math.ceil(((j / TILE_HEIGHT_QUARTER) - (i / TILE_WIDTH_HALF))/2);
int x = (int) Math.ceil(tx)-1;
int y = (int) Math.ceil(ty)-1;
return new int[]{x, y};
}

After replacing the spritesheet with the new one with 128x64 pixels' tiles, I've been able to achieve the desired output partially...
Why I say "partially"? Because I've managed to get the desired result only from the half right part of the map.
I believe it could have something to do with how the map is being painted, I'm not a native English speaker so I might be misunderstanding what the "Notes" section says in OP's link:
Notice that the "origin" of the isometric tile is the top corner. But usually when we draw a sprite it's from the top-left corner
I've called the methods toGrid() and toIso() at the beginning of the program as follows:
int[] coordinates = Game.toIso(2, 1);
System.out.println(coordinates[0] + "-" + coordinates[1]);
int[] coordinates2 = Game.toGrid(coordinates[0], coordinates[1]);
System.out.println(coordinates2[0] + "-" + coordinates2[1]);
And got the following results, (Which indeed are what we were expecting), so we know the methods work correctly:
64-96
2-1
I was sure to modify the Assets file:
public static final int WIDTH = 128, HEIGHT = 64;
Where I also changed the variable names following the Java naming conventions (ALL_WORDS_UPPER_CASE_CONSTANTS) and made it public instead of private
I also changed the Game file:
public static final int TILE_WIDTH = Assets.WIDTH;
public static final int TILE_HEIGHT = Assets.HEIGHT;
public static final int TILE_WIDTH_HALF = TILE_WIDTH / 2;
public static final int TILE_HEIGHT_HALF = TILE_HEIGHT / 2;
public static final int TILE_WIDTH_QUARTER = TILE_WIDTH / 4;
public static final int TILE_HEIGHT_QUARTER = TILE_HEIGHT / 4;
To use those constants on the Assets file and calculate the HALF and QUARTER instead of hardcoding it.
I also believe xOffset shouldn't be public but private as well as some other variables on the program...
The tick() method, doesn't need to calculate the xOffset everytime, so we can get rid of this line inside it:
xOffset = frame.getWidth() / 2 - 65;
I also changed the way you paint the tile you're selecting as:
// Selected tile render
int[] coordsIsoSelected = toIso(x, y);
g.drawImage(Assets.selected, coordsIsoSelected[0], coordsIsoSelected[1], TILE_WIDTH, TILE_HEIGHT, null);
And for the Tolso equations, I changed them to:
public static int[] toIso(int x, int y) {
int i = (x - y) * TILE_WIDTH_HALF;
int j = (x + y) * TILE_HEIGHT_HALF;
i += xOffset;
return new int[] { i, j };
}
Below I adjusted the parenthesis locations:
public static int[] toGrid(int x, int y) {
x -= xOffset;
int i = ((x / TILE_WIDTH_HALF) + (y / TILE_HEIGHT_HALF)) / 2;
int j = ((y / TILE_HEIGHT_HALF) - (x / TILE_WIDTH_HALF)) / 2;
return new int[] { i, j };
}

How to Draw an BufferedImage to a JPanel

I am trying to use some sort of draw method to draw a sprite image to my subclass of JPanel called AnimationPanel. I have created a Spritesheet class which can generate a BufferedImage[] that contains all of the sprites in the sheet. In my AnimationPanel class, which implements Runnable, I am getting that BufferedImage[] from the spritesheet instantiated in the AnimationPanel constructor. I want to be able to loop through this array and display each sprite to the screen. How would I do this? Here are my AnimationPanel and Spritesheet classes.
AnimationPanel
package com.kahl.animation;
import javax.swing.JPanel;
public class AnimationPanel extends JPanel implements Runnable {
//Instance Variables
private Spritesheet sheet;
private int currentFrame;
private Thread animationThread;
private BufferedImage image;
public AnimationPanel(Spritesheet aSheet) {
super();
sheet = aSheet;
setPreferredSize(new Dimension(128,128));
setFocusable(true);
requestFocus();
}
public void run() {
BufferedImage[] frames = sheet.getAllSprites();
currentFrame = 0;
while (true) {
frames[currentFrame].draw(); //some implementation still necessary here
currentFrame++;
if (currentFrame >= frames.length) {
currentFrame = 0;
}
}
}
public void addNotify() {
super.addNotify();
if (animationThread == null) {
animationThread = new Thread(this);
animationThread.start();
}
}
}
Spritesheet
package com.kahl.animation;
import java.awt.image.BufferedImage;
import java.imageio.ImageIO;
import java.io.IOException;
import java.io.File;
public class Spritesheet {
//Instance Variables
private String path;
private int frameWidth;
private int frameHeight;
private int framesPerRow;
private int frames;
private BufferedImage sheet = null;
//Constructors
public Spritesheet(String aPath,int width,int height,int fpr, int numOfFrames) {
path = aPath;
frameWidth = width;
frameHeight = height;
framesPerRow = fpr;
frames = numOfFrames;
try {
sheet = ImageIO.read(getClass().getResourceAsStream());
} catch (IOException e) {
e.printStackTrace();
}
}
//Methods
public int getHeight() {
return frameWidth;
}
public int getWidth() {
return frameWidth;
}
public int getFramesPerRow() {
return framesPerRow;
}
private BufferedImage getSprite(int x, int y, int h, int w) {
BufferedImage sprite = sheet.getSubimage(x,y,h,w);
}
public BufferedImage[] getAllSprites() {
BufferedImage[] sprites = new BufferedImage[frames];
int y = 0;
for (int i = 0; i < frames; i++) {
x = i * frameWidth;
currentSprite = sheet.getSprite(x,y,frameHeight,frameWidth);
sprites.add(currentSprite);
}
return sprites;
}
}

I'd encourage the use of a javax.swing.Timer to control the frame rate, rather than an uncontrolled loop
Once the timer "ticks", you need to increment the current frame, get the current image to be rendered and call repaint on the JPanel
Use Graphics#drawImage to render the image.
See...
Painting in AWT and Swing
Performing Custom Painting
How to use Swing Timers
Graphics#drawImage(Image, int, int, ImageObserver)
for more details
There is a cascading series of issues with your Spritesheet class, apart from the fact that it won't actually compile, there are issues with you returning the wrong values from some methods and relying on values which are better calculated...
I had to modify your code so much, I can't remember most of them
public int getHeight() {
return frameWidth;
}
and
public BufferedImage[] getAllSprites() {
BufferedImage[] sprites = new BufferedImage[frames];
int y = 0;
for (int i = 0; i < frames; i++) {
x = i * frameWidth;
currentSprite = sheet.getSprite(x,y,frameHeight,frameWidth);
sprites.add(currentSprite);
}
return sprites;
}
Stand out as two main examples...
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestSpriteSheet {
public static void main(String[] args) {
new TestSpriteSheet();
}
public TestSpriteSheet() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private Spritesheet spritesheet;
private BufferedImage currentFrame;
private int frame;
public TestPane() {
spritesheet = new Spritesheet("/Sheet02.gif", 240, 220);
Timer timer = new Timer(100, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
currentFrame = spritesheet.getSprite(frame % spritesheet.getFrameCount());
repaint();
frame++;
}
});
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(240, 220);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (currentFrame != null) {
Graphics2D g2d = (Graphics2D) g.create();
int x = (getWidth() - currentFrame.getWidth()) / 2;
int y = (getHeight() - currentFrame.getHeight()) / 2;
g2d.drawImage(currentFrame, x, y, this);
g2d.dispose();
}
}
}
public class Spritesheet {
//Instance Variables
private String path;
private int frameWidth;
private int frameHeight;
private BufferedImage sheet = null;
private BufferedImage[] frameImages;
//Constructors
public Spritesheet(String aPath, int width, int height) {
path = aPath;
frameWidth = width;
frameHeight = height;
try {
sheet = ImageIO.read(getClass().getResourceAsStream(path));
frameImages = getAllSprites();
} catch (IOException e) {
e.printStackTrace();
}
}
public BufferedImage getSprite(int frame) {
return frameImages[frame];
}
//Methods
public int getHeight() {
return frameHeight;
}
public int getWidth() {
return frameWidth;
}
public int getColumnCount() {
return sheet.getWidth() / getWidth();
}
public int getRowCount() {
return sheet.getHeight() / getHeight();
}
public int getFrameCount() {
int cols = getColumnCount();
int rows = getRowCount();
return cols * rows;
}
private BufferedImage getSprite(int x, int y, int h, int w) {
BufferedImage sprite = sheet.getSubimage(x, y, h, w);
return sprite;
}
public BufferedImage[] getAllSprites() {
int cols = getColumnCount();
int rows = getRowCount();
int frameCount = getFrameCount();
BufferedImage[] sprites = new BufferedImage[frameCount];
int index = 0;
System.out.println("cols = " + cols);
System.out.println("rows = " + rows);
System.out.println("frameCount = " + frameCount);
for (int row = 0; row < getRowCount(); row++) {
for (int col = 0; col < getColumnCount(); col++) {
int x = col * getWidth();
int y = row * getHeight();
System.out.println(index + " " + x + "x" + y);
BufferedImage currentSprite = getSprite(x, y, getWidth(), getHeight());
sprites[index] = currentSprite;
index++;
}
}
return sprites;
}
}
}
Remember, animation is the illusion of change over time. You need to provide a delay between each frame of the animation, long enough for the user to recognise it, but short enough to make the animation look smooth.
In the above example, I've used 100 milliseconds, simply as an arbitrary value. It could be possible to use something more like 1000 / spritesheet.getFrameCount(), which will allow a full second for the entire animation (all the frames within one second).
You might need to use different values, for longer or short animations, depending on your needs

Here's some generic code for drawing an image to a JPanel. This method is called to paint your JPanel component.
public void paintComponent (Graphics g)
{
super.paintComponent(g);
//I would have image be a class variable that gets updated in your run() method
g.drawImage(image, 0, 0, this);
}
I may also modify run() to look something like this:
public void run() {
BufferedImage[] frames = sheet.getAllSprites();
currentFrame = 0;
while (true) {
image = frames[currentFrame];
this.repaint(); //explicitly added "this" for clarity, not necessary.
currentFrame++;
if (currentFrame >= frames.length) {
currentFrame = 0;
}
}
}
In regards to only repainting part of the component, it gets a little more complicated
public void run() {
BufferedImage[] frames = sheet.getAllSprites();
currentFrame = 0;
while (true) {
image = frames[currentFrame];
Rectangle r = this.getDirtyRect();
this.repaint(r);
currentFrame++;
if (currentFrame >= frames.length) {
currentFrame = 0;
}
}
}
public Rectangle getDirtyRect() {
int minX=0; //calculate smallest x value affected
int maxX=0; //calculate largest x value affected
int minY=0; //calculate smallest y value affected
int maxY=0; //calculate largest y value affected
return new Rectangle(minX,minY,maxX,maxY);
}

Using Rectangle to Check Intersection of Images

So, I am instructed to: "Modify the Sprite class by implementing the "overlaps" function to return true if any portion of the Sprite passed in as an argument overlaps the current Sprite. You will need to use the x and y coordinates as well as the size of the Sprites."
I was advised to use Rectangles to make this work and check for an intersection. However, I'm not sure if what I have is the correct way to do this: (It's implemented in the boolean overlaps method)
As always, thanks so much for your time.
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Rectangle;
import javax.imageio.ImageIO;
import java.io.File;
import java.io.IOException;
import java.util.Random;
abstract class Sprite
{
private int x;
private int y;
private int size;
private int w;
private int h;
private int xSlope;
private int ySlope;
private Image image;
private static Random rand;
public Sprite(int xIn, int yIn, int width, int height, String imagePath, int imageSize) {
if (rand == null) {
rand = new Random();
}
size = imageSize;
setImage(imagePath);
x = xIn;
y = yIn;
w = width;
h = height;
xSlope = rand.nextInt(11) - 5;
ySlope = rand.nextInt(11) - 5;
}
public int getX() { return x; }
public int getY() { return y; }
public int getSize() { return size; }
public void setSize(int s) { size = s; }
public void setX(int xIn) { x = xIn; }
public void setY(int yIn) { y = yIn; }
public void setImage(String imagePath) {
try {
image = ImageIO.read(new File(imagePath));
} catch (IOException ioe) {
System.out.println("Unable to load image file.");
}
}
public Image getImage() { return image; }
public boolean overlaps(Sprite s) {
int locX = this.getX();
int locY = this.getY();
int overX = s.getX();
int overY = s.getY();
Rectangle R1 = new Rectangle(locX, locY, this.w, this.h);
Rectangle R2 = new Rectangle(overX, overY, s.w, s.h );
boolean intersects = R1.intersects(R2);
return intersects;
}
public void update(Graphics g) {
g.drawImage(getImage(), x, y, getSize(), getSize(), null);
}
public void move() {
// Move the Sprite
int x = getX() + xSlope;
int y = getY() + ySlope;
if (x < 0) x = w;
if (x > w) x = 0;
if (y < 0) y = h;
if (y > h) y = 0;
setX(x);
setY(y);
}
}