Develop Reference

KeyAdapter input in java not working

I just wrote some code to make my player move in my little maze game, but nothing happens. Also my maze is not drawn correct as in the matrix input. I don't figure out why is wrong this code...any help is well appeciated.
Thank you!
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import javax.swing.*;
public class Main extends JPanel {
private static Image white;
private static Image black;
private static Image finish;
private static Image player;
private static int x = 1;
private static int y = 1;
private String matrix[][];
public Main() {
addKeyListener(new Keys());
setFocusable(true);
}
public static String[][] load(String input) {
List<String[]> rows = new ArrayList<>();
try (Scanner scanner = new Scanner(input)) {
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
String[] cols = new String[line.length()];
for (int i = 0; i < cols.length; i++) {
cols[i] = line.substring(i, i + 1);
}
rows.add(cols);
}
}
return rows.toArray(new String[rows.size()][]);
}
public static JFrame buildFrame() {
JFrame frame = new JFrame("Labyrinth Game");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(900, 950);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
return frame;
}
public void moveUp() {
x += 0;
y += -1;
}
public void moveLeft() {
x += -1;
y += 0;
}
public void moveDown() {
x += 0;
y += 1;
}
public void moveRight() {
x += 1;
y += 0;
}
public class Keys extends KeyAdapter {
#Override
public void keyPressed(KeyEvent e) {
int keycode = e.getKeyCode();
// repaint();
if (keycode == KeyEvent.VK_W) {
if (!matrix[getX()][getY() - 1].equals("1")) {
moveUp();
}
}
if (keycode == KeyEvent.VK_A) {
if (!matrix[getX() - 1][getY()].equals("1")) {
moveLeft();
}
}
if (keycode == KeyEvent.VK_S) {
if (!matrix[getX()][getY() + 1].equals("1")) {
moveDown();
}
}
if (keycode == KeyEvent.VK_D) {
if (!matrix[getX() + 1][getY()].equals("1")) {
moveRight();
}
}
}
#Override
public void keyReleased(KeyEvent event) {
}
}
public static void main(String[] args) {
String input = "1111111111111111111111111111111111111111111\n"
+ "1000000010001000001000000010000000100000001\n"
+ "1010111010101010101111101011111010111111101\n"
+ "1010001010100010100000001010000010000010001\n"
+ "1011101010111110101111111010111111111010111\n"
+ "1000101010100000101000001000100010000010001\n"
+ "1011101011101011111011101111111010111110101\n"
+ "1010001000001010000010100000001010000010101\n"
+ "1010111111111010111110111111101011111011101\n"
+ "1010100000100010100000000000101000000000101\n"
+ "1110101111101110111110111011101011111110101\n"
+ "1000100000000010000010100010001000100010001\n"
+ "1011111111111111111011101010111111101011101\n"
+ "1000000000000000100010001010000000001010001\n"
+ "1011111111111011101110111011111111111010111\n"
+ "1000100010001000001010001000100000001010101\n"
+ "1110101011101111111010101110111110111010101\n"
+ "1000101010001000100000101000100000100010001\n"
+ "1011101010111010101111101011101110101111111\n"
+ "1000001010000010000000101000001000100010001\n"
+ "1111111011111110111111101111111011111010101\n"
+ "1000001010000010100010001000000010000010101\n"
+ "1011111010111011101010111011111110101110101\n"
+ "1010000010001010001010001000100000101010101\n"
+ "1010111111101010111011101111101111101011101\n"
+ "1000100000001010101010001000100010101000101\n"
+ "1011111011111010101010111010111010101011101\n"
+ "1010000010001000101010000010001010001000001\n"
+ "1010101110101111101011101111101011111010101\n"
+ "1010101000101000001000101000001000000010101\n"
+ "1011101011111010111110111011101111111110111\n"
+ "1000001000000010000000000010000000000010021\n"
+ "1111111111111111111111111111111111111111111\n";
String[][] matrix = load(input);
JFrame frame = buildFrame();
ImageIcon img = new ImageIcon("C:/Users/Desktop/black20.png");
black = img.getImage();
img = new ImageIcon("C:/Users/Desktop/gri20.png");
white = img.getImage();
img = new ImageIcon("C:/Users/Desktop/finish20.png");
finish = img.getImage();
img = new ImageIcon("C:/Users/Desktop/smiley20.png");
player = img.getImage();
// frame.add(new Player());
JPanel pane = new JPanel() {
#Override
public void paint(Graphics g) {
super.paint(g);
for (int i = 0; i < matrix.length; i++) {
for (int j = 0; j < matrix[0].length; j++) {
if (matrix[i][j].equals("1")) {
g.drawImage(black, i * 20, j * 20, null);
}
if (matrix[i][j].equals("0")) {
g.drawImage(white, i * 20, j * 20, null);
}
if (matrix[i][j].equals("2")) {
g.drawImage(finish, i * 20, j * 20, null);
}
}
}
g.drawImage(player, x * 20, y * 20, null);
}
};
frame.add(pane);
frame.add(new Main());
}
}
It should look like:

Problems/Suggestions:
You're adding more than one component to the JFrame in a default fashion. Since the JFrame's contentPane uses BorderLayout, only one component will display, the last one added, and the other will be completely covered and will remain invisible.
Your Main JPanel is not being used as a true JPanel. Nothing is being added to it, and in fact it looks like it should be a logical class and not a component class.
Rather than using KeyListeners, which are very fidgety when it comes to focus problems, use Key Bindings which will allow you to get around focus issues in a clean and higher level way.
Don't override the JPanel's paint method but rather its paintComponent method as this will give you several advantages, including default use of double buffering for your animation.
Don't give component classes a public int getX() and public int getY() method without care since these override key methods that place the component within its container. Since the Main class shouldn't even extend JPanel, this will end up to be a non-issue for your code, but in the future, it would mess your program up.
When you run into similar problems, such as a KeyListener not working, remove the issue from your big program and try to reproduce it in a small separate program. This will give you a much cleaner environment for helping you to isolate and understand your problem and thereby help you fix it.
Your program is mis-using the static modifier. Your x and y fields should not be static and should not be accessed in a static way.
You've got way too much code within your main method, which is one of the reasons why you likely made x and y static, because you were forced to do so since you're trying to access them within main. The solution is not to make the fields static but to get all that code out of the static world and into the instance world.
Edit
For some reason the question intrigued me, and so I decided to try to M-V-C or Model-View-Controller it if possible and see what I could come up with. So here goes a bunch of classes that sort of work, beginning with a text file that holds the data.
The GUI looks like:
It must be in the same location as the class files since it is obtained as a resource and must have the file name "input.txt"
1111111111111111111111111111111111111111111
1000000010001000001000000010000000100000001
1010111010101010101111101011111010111111101
1010001010100010100000001010000010000010001
1011101010111110101111111010111111111010111
1000101010100000101000001000100010000010001
1011101011101011111011101111111010111110101
1010001000001010000010100000001010000010101
1010111111111010111110111111101011111011101
1010100000100010100000000000101000000000101
1110101111101110111110111011101011111110101
1000100000000010000010100010001000100010001
1011111111111111111011101010111111101011101
1000000000000000100010001010000000001010001
1011111111111011101110111011111111111010111
1000100010001000001010001000100000001010101
1110101011101111111010101110111110111010101
1000101010001000100000101000100000100010001
1011101010111010101111101011101110101111111
1000001010000010000000101000001000100010001
1111111011111110111111101111111011111010101
1000001010000010100010001000000010000010101
1011111010111011101010111011111110101110101
1010000010001010001010001000100000101010101
1010111111101010111011101111101111101011101
1000100000001010101010001000100010101000101
1011111011111010101010111010111010101011101
1010000010001000101010000010001010001000001
1010101110101111101011101111101011111010101
1010101000101000001000101000001000000010101
1011101011111010111110111011101111111110111
1000001000000010000000000010000000000010021
1111111111111111111111111111111111111111111
Next the main program, the one that creates the model, the view, and the controller, hooks them all together, and then displays the GUI:
import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
/**
* link: http://stackoverflow.com/a/41418250/522444
*
* #author Pete
*
*/
#SuppressWarnings("serial")
public class Main2 extends JPanel {
private View mainPanel;
public Main2(MatrixModel matrixModel) {
mainPanel = new View(matrixModel);
new Controller(matrixModel, mainPanel);
setLayout(new BorderLayout());
add(mainPanel, BorderLayout.CENTER);
}
private static void createAndShowGui(MatrixModel model) {
Main2 mainPanel = new Main2(model);
JFrame frame = new JFrame("Main2");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
final MatrixModel model = MatrixUtil.getInput(MatrixUtil.PATH_TO_RSC);
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui(model);
}
});
}
}
Next a utility class with static methods for reading in the text file as a resource and converting it into a Model object:
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class MatrixUtil {
// again this text file must be in the jar file or the code base
// at the same location as the class / java files
public static final String PATH_TO_RSC = "input.txt";
public static MatrixModel getInput(String resourcePath) {
InputStream is = MatrixUtil.class.getResourceAsStream(resourcePath);
if (is == null) {
String text = "resourcePath is not found and not loading text: " + resourcePath;
throw new IllegalArgumentException(text);
}
return getInput(is);
}
public static MatrixModel getInput(InputStream is) {
MatrixModel model = null;
try (Scanner scan = new Scanner(is)) {
List<List<MatrixPosition>> listOfLists = new ArrayList<>();
while (scan.hasNextLine()) {
String line = scan.nextLine();
if (line.trim().isEmpty()) {
continue;
}
List<MatrixPosition> list = new ArrayList<>();
for (char c : line.toCharArray()) {
list.add(MatrixPosition.getMatrixPosition(String.valueOf(c)));
}
listOfLists.add(list);
}
MatrixPosition[][] grid = new MatrixPosition[listOfLists.size()][];
for (int i = 0; i < grid.length; i++) {
List<MatrixPosition> list = listOfLists.get(i);
grid[i] = list.toArray(new MatrixPosition[] {});
}
model = new MatrixModel(grid, new SpritePosition(1, 1));
}
return model;
}
}
Basic enum to represent direction:
public enum Direction {
UP, DOWN, LEFT, RIGHT
}
Another enum to represent a location point in the grid, and whether it is a wall, a coridor or the end as well as static methods to convert from number to MatrixPosition:
public enum MatrixPosition {
WALL(1), CORRIDOR(0), END(2);
private int value;
private MatrixPosition(int value) {
this.value = value;
}
public int getValue() {
return value;
}
public static MatrixPosition getMatrixPosition(int value) {
for (MatrixPosition position : MatrixPosition.values()) {
if (value == position.getValue()) {
return position;
}
}
String text = "value of " + value;
throw new IllegalArgumentException(text);
}
public static MatrixPosition getMatrixPosition(String strValue) {
int value = -1;
try {
value = Integer.parseInt(strValue);
} catch (NumberFormatException e) {
String text = "NumberFormatException for strValue " + strValue;
throw new IllegalAccessError(text);
}
return getMatrixPosition(value);
}
}
A class to represent a position of our sprite, similar to the java.awt.Point class but with row and column fields instead of x and y:
public class SpritePosition {
int row;
int column;
public SpritePosition(int row, int column) {
this.row = row;
this.column = column;
}
public int getRow() {
return row;
}
public void setRow(int row) {
this.row = row;
}
public int getColumn() {
return column;
}
public void setColumn(int column) {
this.column = column;
}
public void setRowColumn(int row, int column) {
this.row = row;
this.column = column;
}
}
The model has property change support code so that it can notify any classes listening to it of any changes in its state. The controller will be the class listening to the model
import java.beans.PropertyChangeListener;
import javax.swing.event.SwingPropertyChangeSupport;
public class MatrixModel {
public static final String SPRITE_POINT = "sprite point";
private SwingPropertyChangeSupport pcSupport = new SwingPropertyChangeSupport(this);
private MatrixPosition[][] grid;
private SpritePosition spritePosition;
public MatrixModel(MatrixPosition[][] grid, SpritePosition spritePosition) {
this.grid = grid;
this.spritePosition = spritePosition;
}
public int getRows() {
return grid.length;
}
public int getColumns() {
return grid[0].length;
}
public MatrixPosition getPosition(SpritePosition p) {
return getPosition(p.row, p.column);
}
public MatrixPosition getPosition(int row, int col) {
return grid[row][col];
}
public void setSpritePoint(SpritePosition spritePosition) {
SpritePosition oldValue = this.spritePosition;
SpritePosition newValue = spritePosition;
this.spritePosition = spritePosition;
pcSupport.firePropertyChange(SPRITE_POINT, oldValue, newValue);
}
public boolean isPointValid(SpritePosition p) {
if (p.column < 0 || p.row < 0) {
return false;
}
if (p.column >= grid[0].length || p.row >= grid.length) {
return false;
}
return grid[p.row][p.column] == MatrixPosition.CORRIDOR;
}
public boolean isMoveValid(Direction direction) {
int row = spritePosition.row;
int column = spritePosition.column;
switch (direction) {
case UP:
return isPointValid(new SpritePosition(row - 1, column));
case DOWN:
return isPointValid(new SpritePosition(row + 1, column));
case LEFT:
return isPointValid(new SpritePosition(row, column - 1));
case RIGHT:
return isPointValid(new SpritePosition(row, column + 1));
default:
return false;
}
}
public void move(Direction direction) {
if (!isMoveValid(direction)) {
String text = "For move to " + direction + "spritePosition: " + spritePosition;
throw new IllegalArgumentException(text);
}
int row = spritePosition.row;
int column = spritePosition.column;
switch (direction) {
case UP:
setSpritePoint(new SpritePosition(row - 1, column));
break;
case DOWN:
setSpritePoint(new SpritePosition(row + 1, column));
break;
case LEFT:
setSpritePoint(new SpritePosition(row, column - 1));
break;
case RIGHT:
setSpritePoint(new SpritePosition(row, column + 1));
break;
default:
break;
}
}
public SpritePosition getSpritePosition() {
return spritePosition;
}
public void addPropertyChangeListener(PropertyChangeListener listener) {
pcSupport.addPropertyChangeListener(listener);
}
public void removePropertyChangeListener(PropertyChangeListener listener) {
pcSupport.removePropertyChangeListener(listener);
}
public void addPropertyChangeListener(String name, PropertyChangeListener listener) {
pcSupport.addPropertyChangeListener(name, listener);
}
public void removePropertyChangeListener(String name, PropertyChangeListener listener) {
pcSupport.removePropertyChangeListener(name, listener);
}
}
Controller class, one that sets up key bindings on the view so that it can listen for key presses, checks if they represent a valid move, and if so then tells the model to make the move. It also adds a listener to the model so that when its state changes, it will tell the view to move the sprite
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.EnumMap;
import java.util.Map;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JComponent;
import javax.swing.KeyStroke;
public class Controller {
private MatrixModel model;
private View view;
private Map<Direction, KeyStroke> dirKeyMap = new EnumMap<>(Direction.class);
public Controller(MatrixModel model, View view) {
this.model = model;
this.view = view;
dirKeyMap.put(Direction.DOWN, KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0));
dirKeyMap.put(Direction.UP, KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0));
dirKeyMap.put(Direction.LEFT, KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0));
dirKeyMap.put(Direction.RIGHT, KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0));
model.addPropertyChangeListener(new ModelListener());
setUpKeyBindings(view);
}
private void setUpKeyBindings(View view) {
int condition = JComponent.WHEN_IN_FOCUSED_WINDOW;
InputMap inputMap = view.getInputMap(condition);
ActionMap actionMap = view.getActionMap();
for (Direction dir : Direction.values()) {
KeyStroke keyStroke = dirKeyMap.get(dir);
hookUp(inputMap, actionMap, dir, keyStroke);
}
}
private void hookUp(InputMap inputMap, ActionMap actionMap, Direction dir, KeyStroke key) {
inputMap.put(key, key.toString());
actionMap.put(key.toString(), new MoveAction(dir, model));
}
public MatrixModel getModel() {
return model;
}
public View getView() {
return view;
}
class ModelListener implements PropertyChangeListener {
#Override
public void propertyChange(PropertyChangeEvent evt) {
if (MatrixModel.SPRITE_POINT.equals(evt.getPropertyName())) {
SpritePosition p = model.getSpritePosition();
view.setSpritePoint(p);
}
}
}
}
#SuppressWarnings("serial")
class MoveAction extends AbstractAction {
private Direction dir;
private MatrixModel model;
public MoveAction(Direction dir, MatrixModel model) {
super(dir.toString());
this.dir = dir;
this.model = model;
}
public void actionPerformed(ActionEvent e) {
if (model.isMoveValid(dir)) {
model.move(dir);
}
}
}
Finally the View class, that extends JPanel, that displays the maze and the sprite:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import javax.swing.JPanel;
#SuppressWarnings("serial")
public class View extends JPanel {
private static final int CELL_WIDTH = 20;
private static final Color CORRIDOR_COLOR = Color.LIGHT_GRAY;
private static final Color WALL_COLOR = Color.DARK_GRAY;
private static final Color END_COLOR = Color.ORANGE;
private static final Color SPRITE_COLOR = Color.RED;
private static final int GAP = 1;
private BufferedImage gridImg = null;
private SpritePosition spritePosition;
private JPanel mainPanel = new JPanel();
public View(MatrixModel matrixModel) {
gridImg = createImg(matrixModel);
spritePosition = matrixModel.getSpritePosition();
}
public JPanel getMainPanel() {
return mainPanel;
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet() || gridImg == null) {
return super.getPreferredSize();
}
int prefW = gridImg.getWidth();
int prefH = gridImg.getHeight();
return new Dimension(prefW, prefH);
}
public void setSpritePoint(SpritePosition spritePosition) {
this.spritePosition = spritePosition;
repaint();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (gridImg != null) {
g.drawImage(gridImg, 0, 0, this);
}
g.setColor(SPRITE_COLOR);
int y = spritePosition.row * CELL_WIDTH + GAP;
int x = spritePosition.column * CELL_WIDTH + GAP;
g.fillRect(x, y, CELL_WIDTH - 2 * GAP, CELL_WIDTH - 2 * GAP);
}
private BufferedImage createImg(MatrixModel matrixModel) {
BufferedImage img = null;
if (matrixModel != null && matrixModel.getRows() > 0) {
int w = matrixModel.getColumns() * CELL_WIDTH;
int h = matrixModel.getRows() * CELL_WIDTH;
img = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
for (int row = 0; row < matrixModel.getRows(); row++) {
for (int col = 0; col < matrixModel.getColumns(); col++) {
MatrixPosition position = matrixModel.getPosition(row, col);
Color c = null;
switch (position) {
case CORRIDOR:
c = CORRIDOR_COLOR;
break;
case WALL:
c = WALL_COLOR;
break;
case END:
c = END_COLOR;
break;
}
g2.setColor(c);
int x = col * CELL_WIDTH;
int y = row * CELL_WIDTH;
g2.fillRect(x, y, CELL_WIDTH, CELL_WIDTH);
}
}
g2.dispose();
}
return img;
}
}

Animate a Java Line drawing using a timer

I am trying to draw two circle on a panel with a line joining them, all after a button is pressed. So far (apart from tweaking locations of the line) this is ok. However, I would like to animate it using a timer. The first circle should appear, then gradually the line will be revealed, and finally the second circle.
I have looked at many examples of timers, but I can't seem to get it to work for me. I must be misunderstanding something.
here is the ball class (for each circle):
package twoBalls;
import java.awt.Color;
import java.awt.Point;
public class Ball {
private int x;
private int y;
private int r;
private Color color;
private Point location;
private Ball parent;
public Ball(int x, int y, int r) {
this.x = x;
this.y = y;
this.r = r;
Point p = new Point(x, y);
setLocation(p);
}
public void setParent(Ball b) {
parent = b;
}
public Ball getParent() {
return parent;
}
public void setx(int x) {
this.x = x;
}
public void sety(int y) {
this.y = y;
}
public int getx() {
return x;
}
public int gety() {
return y;
}
public int getr() {
return r;
}
public void setPreferedSize() {
}
public void setLocation(Point p) {
setx(p.x);
sety(p.y);
location = p;
}
public Point getLocation() {
return location;
}
public void setColor(Color color) {
this.color = color;
}
public Color getColor() {
return color;
}
}
then the class that will store balls in an arrayList. And I think that this is where the actual drawing should take place, along with the timer.
I am trying to set the start and end point of the line to be the same, and increment the end point until it is where it should be, using the timer. I'm probably way of track, but that was the intention!
I have change this class, the if statements in the while loop can now be entered, as I am now comparing different point. But the line doesn't get drawn at all still.
package twoBalls;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.util.ArrayList;
import javax.swing.JPanel;
import javax.swing.Timer;
public class BallsArray extends JPanel implements ActionListener {
private ArrayList<Ball> balls;
private Timer timer;
private final int DELAY = 25;
private int xDest;
private int yDest;
private Point dest;
private Point starts;
private int xStart;
private int yStart;
public BallsArray() {
balls = new ArrayList<Ball>();
timer = new Timer(DELAY, this);
yDest = 0;
xDest = 0;
dest = new Point(xDest, yDest);
starts = new Point(xStart, yStart);
}
public void setDestXY(int x, int y) {
xDest = x;
yDest = y;
dest = new Point(xDest, yDest);
setDest(dest);
}
public void setDest(Point p) {
dest = p;
}
public Point getDest() {
return dest;
}
public void setStartsXY(int x, int y) {
xStart = x;
yStart = y;
starts = new Point(xStart, yStart);
setStarts(starts);
}
public void setStarts(Point p) {
starts = p;
}
public Point getStarts() {
return starts;
}
public void addBall(Ball b) {
balls.add(b);
}
public void addBall(int x, int y, int r) {
balls.add(new Ball(x, y, r));
}
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
for (int i = 0; i < balls.size(); i++) {
if (i == 0) {
paintBall(balls.get(0), g2);
}
if (i != 0) {
int j = i - 1;
Ball bp = balls.get(j);
Ball bc = balls.get(i);
bc.setParent(bp);
paintLine(bc, g2);
paintBall(bc, g2);
}
}
}
public void paintBall(Ball b, Graphics2D g2d) {
Ellipse2D circ = new Ellipse2D.Float(b.getx(), b.gety(), b.getr(),
b.getr());
g2d.draw(circ);
}
public void paintLine(Ball b, Graphics2D g2d) {
timer.start();
if (b != null && b.getLocation() != null) {
Ball parent = b.getParent();
if (parent != null) {
g2d.setColor(Color.GRAY);
if (parent.getLocation() != null && b.getLocation() != null) {
setDest(parent.getLocation());
setStarts(parent.getLocation());
g2d.draw(new Line2D.Float(starts, dest));
}
}
}
}
#Override
public void actionPerformed(ActionEvent e) {
// Not sure what I need to do here
// increment second location somehow
// Point s = getStarts();
Point p = getDest();
Point t = this.getLocation();
while (p != t) {
if (p.x != t.x && p.y != t.y) {
System.out.println("hello");
int x = dest.x;
int y = dest.y;
x++;
y++;
setDestXY(x, y);
p = getDest();
repaint();
} else if (p.x == t.x && p.y != t.y) {
System.out.println("part 2");
int y = dest.y;
y++;
setDestXY(dest.x, y);
p = getDest();
repaint();
} else if (p.x != t.x && p.y == t.y) {
System.out.println("part 3");
int x = dest.x;
x++;
setDestXY(x, dest.y);
p = getDest();
repaint();
}
repaint();
}
}
}
I have had a lot of help online getting this far, I worry I am just beyond my depth now!. I am unsure about the EventQueue/run part below. Here is the class to set it all up:
package twoBalls;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Display implements ActionListener {
private JFrame frame;
private JButton button;
private BallsArray b;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
Display ex = new Display();
}
});
}
public Display() {
b = new BallsArray();
frame = new JFrame();
frame.setSize(800, 500);
frame.setTitle("Show balls");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
button = new JButton("New Ball");
frame.add(button, BorderLayout.SOUTH);
frame.setVisible(true);
button.addActionListener(this);
}
#Override
public void actionPerformed(ActionEvent e) {
Ball ball1 = new Ball(100, 100, 50);
b.addBall(ball1);
b.addBall(200, 200, 50);
frame.add(b, BorderLayout.CENTER);
frame.revalidate();
frame.repaint();
}
}
At the moment it draws the two circles, but not the line at all.

When you make an animation, it helps to use the model / view / controller pattern.
Here's the GUI I created from your code.
I simplified your Ball class. This is all you need to define a ball.
package twoBalls;
import java.awt.Color;
import java.awt.Point;
public class Ball {
private final int radius;
private final Color color;
private final Point center;
public Ball(int x, int y, int radius, Color color) {
this(new Point(x, y), radius, color);
}
public Ball(Point center, int radius, Color color) {
this.center = center;
this.radius = radius;
this.color = color;
}
public int getRadius() {
return radius;
}
public Color getColor() {
return color;
}
public Point getCenter() {
return center;
}
}
I created the GUIModel class to hold all of the information your GUI needs. This separates the model from the view.
package twoBalls;
import java.awt.Point;
import java.util.ArrayList;
import java.util.List;
public class GUIModel {
private double direction;
private double distance;
private List<Ball> balls;
private Point lineStartPoint;
private Point lineEndPoint;
public GUIModel() {
this.balls = new ArrayList<>();
}
public void addBall(Ball ball) {
this.balls.add(ball);
}
public List<Ball> getBalls() {
return balls;
}
public void calculatePoints() {
this.lineStartPoint = balls.get(0).getCenter();
this.lineEndPoint = balls.get(1).getCenter();
this.distance = Point.distance(lineStartPoint.x, lineStartPoint.y,
lineEndPoint.x, lineEndPoint.y);
this.direction = Math.atan2(lineEndPoint.y - lineStartPoint.y,
lineEndPoint.x - lineStartPoint.x);
}
public Point getCurrentPoint(int pos, int total) {
double increment = distance / total;
double length = increment * pos;
double x = lineStartPoint.x + Math.cos(direction) * length;
double y = lineStartPoint.y - Math.sin(direction) * length;
x = Math.round(x);
y = Math.round(y);
return new Point((int) x, (int) y);
}
public Point getLineStartPoint() {
return lineStartPoint;
}
}
This class holds the two Ball instances, and calculates the length and direction of the line, divided into total increments.
Now that we've defined the model classes, let's look at the view classes. The first is your Display class.
package twoBalls;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Display implements Runnable {
private GUIModel guiModel;
private JFrame frame;
public static void main(String[] args) {
EventQueue.invokeLater(new Display());
}
public Display() {
this.guiModel = new GUIModel();
Ball ball1 = new Ball(150, 200, 50, Color.BLUE);
Ball ball2 = new Ball(450, 200, 50, Color.GREEN);
guiModel.addBall(ball1);
guiModel.addBall(ball2);
guiModel.calculatePoints();
}
#Override
public void run() {
frame = new JFrame();
frame.setTitle("Show Balls Animation");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new JPanel();
panel.setLayout(new BorderLayout());
DrawingPanel drawingPanel = new DrawingPanel(guiModel);
panel.add(drawingPanel, BorderLayout.CENTER);
panel.add(createButtonPanel(drawingPanel), BorderLayout.SOUTH);
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
private JPanel createButtonPanel(DrawingPanel drawingPanel) {
JPanel panel = new JPanel();
JButton startButton = new JButton("Start Animation");
startButton.addActionListener(new StartAnimation(drawingPanel));
panel.add(startButton);
return panel;
}
public class StartAnimation implements ActionListener {
private DrawingPanel drawingPanel;
public StartAnimation(DrawingPanel drawingPanel) {
this.drawingPanel = drawingPanel;
}
#Override
public void actionPerformed(ActionEvent event) {
LineRunnable runnable = new LineRunnable(drawingPanel);
new Thread(runnable).start();
}
}
}
The constructor of the Display class sets up the GUI model.
The run method of the Display class constructs the GUI, and starts the animation.
See how I've separated the model and view.
The StartAnimation class is your controller. It starts the animation when you left click on the JButton. I'll discuss the LineRunnable class later.
Next, let's take a look at the DrawingPanel class.
package twoBalls;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import javax.swing.JPanel;
public class DrawingPanel extends JPanel {
private static final long serialVersionUID = -3709678584255542338L;
private boolean drawLine;
private int pos;
private int total;
private GUIModel guiModel;
public DrawingPanel(GUIModel guiModel) {
this.guiModel = guiModel;
this.drawLine = false;
this.setPreferredSize(new Dimension(600, 400));
}
public boolean isDrawLine() {
return drawLine;
}
public void setDrawLine(boolean drawLine) {
this.drawLine = drawLine;
}
public void setPos(int pos) {
this.pos = pos;
repaint();
}
public void setTotal(int total) {
this.total = total;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
for (Ball ball : guiModel.getBalls()) {
g2d.setColor(ball.getColor());
Point center = ball.getCenter();
int radius = ball.getRadius();
g2d.fillOval(center.x - radius, center.y - radius, radius + radius,
radius + radius);
}
if (isDrawLine()) {
g2d.setColor(Color.BLACK);
g2d.setStroke(new BasicStroke(5.0F));
Point a = guiModel.getLineStartPoint();
Point b = guiModel.getCurrentPoint(pos, total);
g2d.drawLine(a.x, a.y, b.x, b.y);
}
}
}
The only thing this view class does is draw the balls and the line. The responsibility for calculating the length of the line belongs in the model.
I set the preferred size here, and use the pack method in the Display class to get the size of the JFrame. You usually want to know the dimensions of the drawing area, rather than the entire window.
Finally, let's look at the LineRunnable class. This is the class that controls the animation.
package twoBalls;
import java.awt.EventQueue;
public class LineRunnable implements Runnable {
private int total;
private DrawingPanel drawingPanel;
public LineRunnable(DrawingPanel drawingPanel) {
this.drawingPanel = drawingPanel;
this.total = 240;
}
#Override
public void run() {
setDrawLine();
for (int pos = 0; pos <= total; pos++) {
setPos(pos);
sleep(50L);
}
}
private void setDrawLine() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
drawingPanel.setDrawLine(true);
drawingPanel.setTotal(total);
}
});
}
private void setPos(final int pos) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
drawingPanel.setPos(pos);
}
});
}
private void sleep(long delay) {
try {
Thread.sleep(delay);
} catch (InterruptedException e) {
}
}
}
In the run method, we divide the line into 240 segments, and draw a segment every 50 milliseconds. It takes the GUI 12 seconds to draw the line. You can play with these numbers if you wish.
The for loop is a classic animation loop. First you update the model, which I'm doing through the drawing panel. Then you sleep.
This animation loop is running on a different thread from the GUI thread. This keeps the GUI responsive. Since the loop is running on a different thread, we have to use the invokeLater method to draw on the Event Dispatch thread.
I hope this was helpful to you. Divide and conquer. Don't let a class do more than one thing.

How to paint over a JPanel?

I (A novice programmer) am trying to paint an oval over a JPanel. I am trying to use the method paint. However, it requires a Graphics argument. I get a NullPointerException when I include my Graphics as a argument because it is null, but I do not know how else to paint the oval. I tried repaint instead but nothing happened. Any help would be appreciated. Here is my main class:
public class Checkers extends JPanel{
public static final int BOARDSQUARES = 8;
public static final int BOARDSIZE = 75;
private JPanel[][] board;
private final Point point1;
private final LineBorder border1;
public JFrame frame;
checkerPiece piece = new checkerPiece(this);
Graphics g;
public Checkers(){
board = new JPanel[BOARDSQUARES][BOARDSQUARES];
point1 = new Point (BOARDSIZE,BOARDSIZE);
border1=new LineBorder(Color.BLACK, 1);
}
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
Checkers checkers = new Checkers();
checkers.frame=checkers.createJFrame();
checkers.board =checkers.createBoard(checkers.board, checkers.point1, checkers.border1);
for (int y=0;y<BOARDSQUARES;y++){
for (int x = 0;x<BOARDSQUARES;x++){
checkers.frame.getContentPane().add(checkers.board[y][x]);
}
}
checkers.paint(checkers.g);
}
private JPanel[][] createBoard (JPanel[][] board, Point point, LineBorder border1){
for (int row = 0; row<BOARDSQUARES;row++){
point.y=BOARDSIZE;
for (int col = 0; col <BOARDSQUARES;col++){
board[row][col] = new JPanel();
board[row][col].setLocation(point);
board[row][col].setVisible(true);
board[row][col].setSize(BOARDSIZE,BOARDSIZE);
board[row][col].setOpaque(true);
if ((row%2==0&&col%2==0)||(row%2==1&&col%2==1)){
board[row][col].setBackground(new Color (230,200,150));
} else if ((row%2==0&&col%2==1)||(row%2==1&&col%2==0)) {
board[row][col].setBackground(new Color (165, 42,42) );
}
board[row][col].setBorder(border1);
point.y = point.y+BOARDSIZE;
}
point.x=point.x+BOARDSIZE;
}
return board;
}
private JFrame createJFrame (){
JFrame mainFrame = new JFrame("Checkers");
mainFrame.setSize(1000,1000);
mainFrame.setVisible(true);
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.add(new Checkers());
return mainFrame;
}
#Override
public void paint (Graphics g){
System.out.println("hi");
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
piece.paint(g2d,board[0][0].getLocation().x,board[0][0].getLocation().y,Color.BLACK);
}
}
A necessary snippet from my other class (cherkerPiece piece):
public void paint (Graphics2D g, int x, int y, Color color){
g.setColor(color);
g.fillOval(x, y, DIAMETER, DIAMETER);
}
Thank you for your help

To create something as complex as a checkers game, you should follow the model / view / controller pattern when creating your Java Swing GUI.
I created a model class for a checker board square and another model class for a checker piece. I created a model class for the checker board and another model class to hold all of the checker pieces.
I created a view class to draw the checker board. I created another view class to create the main window.
I did not create any controller classes. This code just shows you how to draw a checker board. I put all of the classes together to make it easier to paste the code. You should separate the classes into separate Java files.
package com.ggl.testing;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.Rectangle;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class CheckerBoard implements Runnable {
private Board board;
private CheckerBoardPanel checkerBoardPanel;
private JFrame frame;
private Pieces pieces;
public static void main(String[] args) {
SwingUtilities.invokeLater(new CheckerBoard());
}
public CheckerBoard() {
this.board = new Board();
this.pieces = new Pieces();
}
#Override
public void run() {
frame = new JFrame("Checker Board");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
checkerBoardPanel = new CheckerBoardPanel(board, pieces);
frame.add(checkerBoardPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public class CheckerBoardPanel extends JPanel {
private static final long serialVersionUID = 3770663347384271771L;
private Board board;
private Pieces pieces;
public CheckerBoardPanel(Board board, Pieces pieces) {
this.board = board;
this.pieces = pieces;
this.setPreferredSize(board.getPreferredSize());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Square[][] checkerBoard = board.getBoard();
for (int row = 0; row < checkerBoard.length; row++) {
for (int column = 0; column < checkerBoard[row].length; column++) {
Square square = checkerBoard[row][column];
Rectangle drawingRectangle = square.getDrawingRectangle();
g.setColor(square.getColor());
g.fillRect(drawingRectangle.x, drawingRectangle.y,
drawingRectangle.width, drawingRectangle.height);
}
}
List<Piece> checkerPieces = pieces.getPieces();
for (Piece checkerPiece : checkerPieces) {
Point coordinate = checkerPiece.getCoordinate();
Rectangle drawingRectangle = checkerBoard[coordinate.x][coordinate.y]
.getDrawingRectangle();
int x = drawingRectangle.x + drawingRectangle.width / 2;
int y = drawingRectangle.y + drawingRectangle.height / 2;
int radius = board.getSquareWidth() * 2 / 6;
g.setColor(checkerPiece.getColor());
g.fillOval(x - radius, y - radius, radius + radius, radius
+ radius);
}
}
}
public class Board {
private static final int BOARD_WIDTH = 8;
private static final int SQUARE_WIDTH = 64;
private Square[][] board;
public Board() {
this.board = initalizeBoard(BOARD_WIDTH, SQUARE_WIDTH);
}
private Square[][] initalizeBoard(int boardWidth, int squareWidth) {
Square[][] board = new Square[boardWidth][boardWidth];
int x = 0;
int y = 0;
for (int row = 0; row < boardWidth; row++) {
for (int column = 0; column < boardWidth; column++) {
Square square = new Square();
if (isLightSquare(row, column)) {
square.setColor(Color.WHITE);
} else {
square.setColor(Color.LIGHT_GRAY);
}
square.setCoordinate(new Point(row, column));
square.setDrawingRectangle(new Rectangle(x, y, squareWidth,
squareWidth));
board[row][column] = square;
x += squareWidth;
}
x = 0;
y += squareWidth;
}
return board;
}
public boolean isLightSquare(int row, int column) {
if (row % 2 == 0) {
if (column % 2 == 0) {
return true;
} else {
return false;
}
} else {
if (column % 2 == 0) {
return false;
} else {
return true;
}
}
}
public Dimension getPreferredSize() {
int width = SQUARE_WIDTH * 8 + 1;
return new Dimension(width, width);
}
public Square[][] getBoard() {
return board;
}
public int getSquareWidth() {
return SQUARE_WIDTH;
}
}
public class Square {
private Color color;
private Point coordinate;
private Rectangle drawingRectangle;
public Point getCoordinate() {
return coordinate;
}
public void setCoordinate(Point coordinate) {
this.coordinate = coordinate;
}
public Rectangle getDrawingRectangle() {
return drawingRectangle;
}
public void setDrawingRectangle(Rectangle drawingRectangle) {
this.drawingRectangle = drawingRectangle;
}
public Color getColor() {
return color;
}
public void setColor(Color color) {
this.color = color;
}
}
public class Pieces {
private List<Piece> pieces;
public Pieces() {
this.pieces = addPieces();
}
private List<Piece> addPieces() {
List<Piece> pieces = new ArrayList<Piece>();
Piece piece = new Piece();
piece.setColor(Color.RED);
piece.setCoordinate(new Point(2, 1));
pieces.add(piece);
piece = new Piece();
piece.setColor(Color.BLACK);
piece.setCoordinate(new Point(5, 0));
pieces.add(piece);
// Add the rest of the red and black pieces here
return pieces;
}
public List<Piece> getPieces() {
return pieces;
}
public void addPiece(Piece piece) {
this.pieces.add(piece);
}
}
public class Piece {
private Color color;
private Point coordinate;
public Color getColor() {
return color;
}
public void setColor(Color color) {
this.color = color;
}
public Point getCoordinate() {
return coordinate;
}
public void setCoordinate(Point coordinate) {
this.coordinate = coordinate;
}
}
}

you need to add a class that extends Canvas and do all your painting in that class. like this
public class FirstWindow extends JFrame
{
/**
*
*/
private static final long serialVersionUID = 1L;
public FirstWindow()
{
super("Kayte does not go to water parks");
setSize(500, 500);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setResizable(false);
}
}
public class Start extends Canvas implements Runnable
public class Main
{
public static void main(String arg[])
{
FirstWindow fw = new FirstWindow();
Start game = new Start(500, 500);
fw.add(game);
fw.setVisible(true);
new Thread(game).start();
}
}

The following code will not render

I believe the code will speak for itself, but in general the point of the code is the have a Map class that will take in an array of BufferedImages, x values, and y values, to compose a map of many layers (first layer being the BufferedImage array at 0, starting at the x value at 0 and the y value at 0, and so on). The main job of the map class, is to take each pixel of each image and convert them to Block Objects, which are just simply rectangles with a color (Includes a BufferedImage, because after it works, I will replace the color with the Image. Also includes an integer to specify which layer (1 being index 0) its allowed on with 0 meaning it can exist among all layers). In the end, when I call Render() on a Map object, the map object should do all the work in rendering the blocks into the correct positions. The largest problem with all of this is that I get no sytax or compiler errors, so my logic is what is messed up and I can not figure it out!
Thanks in advance, and if the question is confusing please tell me!
The Map Class:
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
public class Map {
private int width;
private int height;
public int getWidth() { return width; }
public int getHeight() { return height; }
private int xPos;
private int yPos;
public int getX(int i)
{
return xPos;
}
public int getY(int i)
{
return yPos;
}
public void setPosition(int x, int y) { xPos = x; yPos = y; }
private int[] xStarts;
private int[] yStarts;
private ArrayList<BufferedImage> layersList = new ArrayList<BufferedImage>();
public void addLayer(BufferedImage image) { layersList.add(image); }
public void setLayer(int i, BufferedImage image) { layersList.set(i, image); }
private Block[][][] blocksArray;
private boolean beenInitialized = false;
public Map(BufferedImage[] images, int[] x, int[] y){
for (BufferedImage image : images){
layersList.add(image);
xStarts = x;
yStarts = y;
}
}
public void initialize(){
int widthMax = 0;
int heightMax = 0;
for (BufferedImage image : layersList){
if (image.getHeight() > heightMax) { heightMax = image.getHeight(); }
if (image.getWidth() > widthMax) { widthMax = image.getWidth(); }
}
width = widthMax;
height = heightMax;
blocksArray = new Block[layersList.size()][width][height];
for (int i = 0; i < layersList.size(); i++){
int currentLayer = i;
for (int y = 0; y < layersList.get(i).getHeight(); y++){
for (int x = 0; x < layersList.get(i).getWidth(); x++){
int colorCode = layersList.get(i).getRGB(x, y);
boolean error = true;
Block b = null;
for (int c = 0; c < Block.BLOCKS.size(); c++){
if (Block.BLOCKS.get(i).getColorCode() == colorCode && (Block.BLOCKS.get(i).getLayerCode() == currentLayer || Block.BLOCKS.get(i).getLayerCode() == 0)){
b = Block.BLOCKS.get(c);
error = false;
}
}
if (!error){
blocksArray[currentLayer][x][y] = b;
} else {
Block bb = new Block(false, colorCode);
bb.initialize();
blocksArray[currentLayer][x][y] = bb;
}
}
}
}
beenInitialized = true;
}
public void render(Graphics2D g2d){
if (beenInitialized){
for (int i = 0; i < layersList.size(); i++){
for (int y = yStarts[i]; y < layersList.get(i).getHeight() + yStarts[i]; y += Block.SIZE){
int currentY = 0;
for (int x = xStarts[i]; x < layersList.get(i).getWidth() + xStarts[i]; x += Block.SIZE){
int currentX = 0;
blocksArray[i][currentX][currentY].setPosition(x, y);
blocksArray[i][currentX][currentY].render(g2d);
currentX ++;
}
currentY++;
}
}
}
}
public void updatePosition(int x, int y){
xPos += x;
yPos += y;
}
}
The Block Class:
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
public class Block {
public static final int SIZE = 32;
public static final boolean DEBUG = true;
public static ArrayList<Block> BLOCKS = new ArrayList<Block>();
private Color debugColor;
public Color getColor() { return debugColor; }
public void setColor(Color color) { debugColor = color; }
private BufferedImage blockIcon;
public BufferedImage getIcon() { return blockIcon; }
public void setIcon(BufferedImage icon) { blockIcon = icon; }
private int xPos;
private int yPos;
public int getX() { return xPos; }
public int getY() { return yPos; }
public void setPosition(int x, int y) { xPos = x; yPos = y; }
private Rectangle blockShape;
public Rectangle getShape() { return blockShape; }
private int colorCode;
public int getColorCode() { return colorCode; }
private boolean colides;
public boolean doesColide() { return colides; }
private int layerCode;
public int getLayerCode() { return layerCode; }
private boolean beenInitialized = false;
public Block(boolean colides, int layerCode){
this.colides = colides;
this.layerCode = layerCode;
}
public void initialize(){
blockShape = new Rectangle(xPos, yPos, SIZE, SIZE);
int r = (colorCode >> 16) & 0x000000FF;
int g = (colorCode >> 8) & 0x000000FF;
int b = (colorCode) & 0x000000FF;
debugColor = new Color(r, g, b);
BLOCKS.add(this);
beenInitialized = true;
}
public void render(Graphics2D g2d){
if (beenInitialized){
if (DEBUG){
g2d.setColor(debugColor);
if (colides){
g2d.fill(blockShape);
} else {
g2d.draw(blockShape);
}
} else{
}
}
}
}
And finally the Game Class (I threw this together JUST to show a window for testing):
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Game extends JFrame{
public Game(){
super("Test");
try{
layer1 = ImageIO.read(getClass().getResourceAsStream("/layer1.png"));
layer2 = ImageIO.read(getClass().getResourceAsStream("/layer2.png"));
} catch (Exception ex) { ex.printStackTrace(); }
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setResizable(false);
setLayout(new BorderLayout());
add(new panel(), BorderLayout.CENTER);
pack();
setLocationRelativeTo(null);
setVisible(true);
}
public static void main(String[] args){
new Game();
}
private int[] xStartPositions = {0, 0};
private int[] yStartPositions = {0, 0};
private BufferedImage layer1;
private BufferedImage layer2;
private BufferedImage[] imageArray = {layer1, layer2};
private Map map;
public class panel extends JPanel{
public panel(){
setMinimumSize( new Dimension(1200, 675));
setMaximumSize( new Dimension(1200, 675));
setPreferredSize( new Dimension(1200, 675));
setVisible(true);
map = new Map(imageArray, xStartPositions, yStartPositions);
}
public void paint(Graphics g){
Graphics2D g2d = (Graphics2D) g;
map.render(g2d);
}
}
}

The initialize method of Map is never called, therefore Map will never render...
Some feedback...
Don't ever override paint, use paintComponent instead (it's very rare that you would need to override paint...
Make sure you are calling super.paintXxx - there's a lot of important working going on in the background that you don't want to miss or replicate...
Instead of extending from a top level container like JFrame, start by extending from JPanel and add this to a frame you create instead
Beware of static variables, this might cause you more problems ;)
You may also want to have a read through Initial Threads

Help with adding a paddle to a JFrame

This is an excerise i have to complete for a uni course, its not a marked assignment and i could do with a bit of help. I can get the ball to appear on the screen and bounce of the sides, it doesnt matter at the moment if it falls through the bottom of the screen and i can get the paddle to appear on the screen at different times but i cant get them both to appear at the same time. Help please
Here are my classes
MainClass
package movingball;
public class Main
{
public static void main (String []args)
{
MovingBall world = new MovingBall("Moving Ball");
world.setVisible(true);
world.move();
}
}
BallClass
package movingball;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;
public class Ball
{
private final int RADIUS = 10;
private Point pos;
private Color ballColour;
private int yChange = 2;
private int xChange = 1;
private int height, width;
private int change;
public Ball (int frameWidth, int frameHeight)
{
change = 3;
ballColour = Color.RED;
width = frameWidth;
height = frameHeight;
pos = new Point();
pos.x = (int)(Math.random() * (width - RADIUS)) + RADIUS;
pos.y = (int)(Math.random() * (height/2 - RADIUS)) + RADIUS;
}
//There are lots of ways you can updateBallState
//Note that the menu bar occupies some of the visible space
public void move()
{
if(pos.y < RADIUS)
{
yChange = - yChange;
}
if(pos.x < RADIUS)
{
xChange = -xChange;
}
if(pos.x > width - RADIUS)
{
xChange = -xChange;
}
if(pos.y < height - RADIUS)
{
pos.translate(xChange, yChange);
}
if(pos.x < width - RADIUS)
{
pos.translate(xChange, yChange);
}
}
public void updateBallState()
{
if (pos.y + change < height - 3*RADIUS)
{
pos.translate(0, change);
// change++; //accelerate
}
}
//This method can be called with a provided graphics context
//to draw the ball in its current state
public void draw(Graphics g)
{
g.setColor(ballColour);
g.fillOval(pos.x - RADIUS, pos.y - RADIUS, 2*RADIUS, 2*RADIUS);
}
public void bounce()
{
yChange = -yChange;
pos.translate(xChange, yChange);
}
public Point getPosition()
{
return pos;
}
}
BallGame
package movingball;
import java.awt.Graphics;
import java.awt.event.*;
public class BallGame extends MovingBall
{
private Paddle myPaddle = new Paddle(FRAME_WIDTH, FRAME_HEIGHT);
public BallGame(String title)
{
super(title);
addKeyListener(new KeyList());
}
public void paint(Graphics g)
{
super.paint(g);
myPaddle.paint(g);
if(isContact())
{
myBall.bounce();
}
else
{
myPaddle.paint(g);
}
}
public boolean isContact()
{
if (myPaddle.area().contains(myBall.getPosition()))
{
return true;
}
else
{
return false;
}
}
public class KeyList extends KeyAdapter
{
public void keyPressed(KeyEvent k)
{
if(k.getKeyCode() == KeyEvent.VK_LEFT)
{
myPaddle.moveLeft();
}
if(k.getKeyCode() == KeyEvent.VK_RIGHT)
{
myPaddle.moveRight();
}
}
}
}
MovingBall class
package movingball;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MovingBall extends JFrame
{
protected final int FRAME_WIDTH = 240;
protected final int FRAME_HEIGHT = 320;
protected Ball myBall = new Ball(FRAME_WIDTH, FRAME_HEIGHT);
public MovingBall (String title)
{
super(title);
setSize(FRAME_WIDTH, FRAME_HEIGHT);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void paint(Graphics g)
{
super.paint(g);
myBall.draw(g);
}
public void move()
{
while(true)
{
myBall.move();
repaint();
try
{
Thread.sleep(50);
}
catch(InterruptedException e)
{
System.exit(0);
}
}
}
}
Paddle class
package movingball;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Paddle
{
private Color paddleColour = Color.GREEN;
private int x,y;
private int paddleWidth = 20;
private int paddleHeight = 10;
private int move = 5;
/** Creates a new instance of Paddle */
public Paddle(int frameWidth, int frameHeight)
{
x =(int)(Math.random()*(frameWidth - paddleWidth));
y = frameHeight - paddleHeight;
}
public void moveRight()
{
x = x + move;
}
public void moveLeft()
{
x = x - move;
}
public Rectangle area()
{
return new Rectangle(x,y, paddleWidth, paddleHeight);
}
public void paint(Graphics g)
{
g.setColor(paddleColour);
g.fillRect(x,y,paddleWidth, paddleHeight);
}
}

Here are a couple of pointers to get you started. I have a lot of things to suggest but I'll just say this to get you further than you are now. You want your JFrame to be double-buffered. That's the first step. To do this, create a new buffer strategy for your JFrame after making it visible:
world.setVisible(true);
world.createBufferStrategy(2);
As for why your Paddle isn't painting? You're going to kick yourself. Look at this line:
MovingBall world = new MovingBall("Moving Ball");
You're not actually creating a BallGame, which is where the logic for painting the paddle is contained! (BallGame.paint()) Try:
BallGame world = new BallGame("Moving Ball");