My restart button of the game does not work and it multiples when it is clicked. I do not understand Java perfectly I am considering myself good.
Main of the game
package snake_game;
public class snake {
public static void main(String arg[]) {
new GameFrame();
// is exacly the same as frame f = new frame();
// this is shorter and does the same job
}
}
GamePanel
package snake_game;
// import java.awt.event.ActionEvent;
// import java.awt.event.ActionListener;
// import java.awt.Graphics;
// import java.awt.event.KeyAdapter;
// import java.awt.event.KeyEvent;
// or I could write simply
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.Random;
import javax.swing.JPanel;
public class GamePanel extends JPanel implements ActionListener {
// panal dimentions
static final int SCREEN_WIDTH = 600;
static final int SCREEN_HEIGHT = 600;
// panal dimentions
// size
static final int UNIT_SIZE = 25;
// size to make 600 * 600 = 1200 px equel between 25 px
static final int GAME_UNITS = (SCREEN_WIDTH * SCREEN_HEIGHT) / UNIT_SIZE;
// size
// delay how fast the game will be
static final int DELAY = 75;
// delay
// dimentions
final int x[] = new int[GAME_UNITS];
final int y[] = new int[GAME_UNITS];
// dimentions
// snake
int bodyParts = 6;
// snake
// apple
int appleEaten;
int appleX;
int appleY;
// apple
char direction = 'R';
boolean running = false;
Timer timer;
Random random;
GamePanel game;
JButton resetButton;
GamePanel() {
random = new Random();
this.setPreferredSize(new Dimension(SCREEN_WIDTH, SCREEN_HEIGHT));
this.setBackground(Color.black);
this.setFocusable(true);
this.addKeyListener(new MyKeyAdapter());
startGame();
// when we want to make the program to continie we must say what the programm
// must execute next
}
public void startGame() {
newApple();
running = true;
timer = new Timer(DELAY, this);
timer.start();
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
draw(g);
}
public void draw(Graphics g) {
if (running) {
for (int i = 0; i < SCREEN_HEIGHT / UNIT_SIZE; i++) {
g.drawLine(i * UNIT_SIZE, 0, i * UNIT_SIZE, SCREEN_HEIGHT);
g.drawLine(0, i * UNIT_SIZE, i * SCREEN_WIDTH, i * UNIT_SIZE);
}
g.setColor(Color.red);
g.fillOval(appleX, appleY, UNIT_SIZE, UNIT_SIZE);
for (int i = 0; i < bodyParts; i++) {
if (i == 0) {
g.setColor(Color.green);
g.fillRect(x[i], y[i], UNIT_SIZE, UNIT_SIZE);
} else {
g.setColor(new Color(45, 180, 0));
// random color
g.setColor(new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)));
// random color
g.fillRect(x[i], y[i], UNIT_SIZE, UNIT_SIZE);
}
}
g.setColor(Color.red);
g.setFont(new Font("Ink Free", Font.BOLD, 30));
FontMetrics metrics = getFontMetrics(g.getFont());
g.drawString("SCORE:" + appleEaten, (SCREEN_WIDTH - metrics.stringWidth("SCORE:" + appleEaten)) / 2,
g.getFont().getSize());
} else {
gameOver(g);
}
}
public void newApple() {
appleX = random.nextInt((int) (SCREEN_WIDTH / UNIT_SIZE)) * UNIT_SIZE;
appleY = random.nextInt((int) (SCREEN_HEIGHT / UNIT_SIZE)) * UNIT_SIZE;
}
public void move() {
for (int i = bodyParts; i > 0; i--) {
x[i] = x[i - 1];
y[i] = y[i - 1];
}
switch (direction) {
case 'U':
y[0] = y[0] - UNIT_SIZE;
break;
case 'D':
y[0] = y[0] + UNIT_SIZE;
break;
case 'L':
x[0] = x[0] - UNIT_SIZE;
break;
case 'R':
x[0] = x[0] + UNIT_SIZE;
break;
}
}
public void checkApple() {
if ((x[0] == appleX) && (y[0] == appleY)) {
bodyParts++;
appleEaten++;
newApple();
}
}
public void checkCollisions() {
// check if head collides with body
for (int i = bodyParts; i > 0; i--) {
if ((x[0] == x[i]) && (y[0] == y[i])) {
running = false;
}
}
// check if head touches left border
if (x[0] < 0) {
running = false;
}
// check if head touches right border
if (x[0] > SCREEN_WIDTH) {
running = false;
}
// check if head touches top border
if (y[0] < 0) {
running = false;
}
// check if head touches bottom border
if (y[0] > SCREEN_HEIGHT) {
running = false;
}
if (!running) {
timer.stop();
}
}
public void gameOver(Graphics g) {
// score
g.setColor(Color.red);
g.setFont(new Font("Ink Free", Font.BOLD, 30));
FontMetrics metrics1 = getFontMetrics(g.getFont());
g.drawString("SCORE:" + appleEaten, (SCREEN_WIDTH - metrics1.stringWidth("SCORE:" + appleEaten)) / 2,
g.getFont().getSize());
// game over text
g.setColor(Color.red);
g.setFont(new Font("Ink Free", Font.BOLD, 75));
FontMetrics metrics2 = getFontMetrics(g.getFont());
g.drawString("Game Over", (SCREEN_WIDTH - metrics2.stringWidth("Game Over")) / 2, SCREEN_HEIGHT / 2);
// restart button
resetButton = new JButton();
resetButton.setText("Restart");
resetButton.setSize(100, 50);
resetButton.setLocation(150, 150);
resetButton.addActionListener(this);
game = new GamePanel();
this.add(resetButton);
this.add(game);
this.setVisible(true);
// restart button
}
#Override
public void actionPerformed(ActionEvent e) {
if (running) {
move();
checkApple();
checkCollisions();
}
repaint();
// restart button
if (e.getSource() == resetButton) {
this.remove(game);
game = new GamePanel();
this.add(game);
resetButton.setVisible(false);
SwingUtilities.updateComponentTreeUI(this);
// restart button
}
}
public class MyKeyAdapter extends KeyAdapter {
#Override
public void keyPressed(KeyEvent e) {
switch (e.getKeyCode()) {
case KeyEvent.VK_LEFT:
if (direction != 'R') {
direction = 'L';
}
break;
case KeyEvent.VK_RIGHT:
if (direction != 'L') {
direction = 'R';
}
break;
case KeyEvent.VK_UP:
if (direction != 'D') {
direction = 'U';
}
break;
case KeyEvent.VK_DOWN:
if (direction != 'U') {
direction = 'D';
}
break;
}
}
}
}
GameFrame
package snake_game;
import javax.swing.JFrame;
public class GameFrame extends JFrame {
GameFrame() {
GamePanel panel = new GamePanel();
this.add(panel);
this.setTitle("Snake");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setResizable(false);
this.pack();
this.setVisible(true);
this.setLocationRelativeTo(null);
this.setUndecorated(false);
}
}
Introduction
I copied your code into my Eclipse IDE and ran it as is. I received the following runtime error.
Exception in thread "main" java.awt.IllegalComponentStateException: The frame is displayable.
at java.desktop/java.awt.Frame.setUndecorated(Frame.java:926)
at com.ggl.testing.SnakeGame$GameFrame.<init>(SnakeGame.java:41)
at com.ggl.testing.SnakeGame.main(SnakeGame.java:24)
Oracle has a helpful tutorial, Creating a GUI With Swing. Skip the Learning Swing with the NetBeans IDE section. Pay close attention to the Concurrency in Swing section.
I've been writing Swing code for over 10 years, and I have the Oracle website bookmarked in my browser. I still look up how to use certain components to make sure I'm using them correctly.
The first thing I did was to slow down your snake so I could test the game. I changed the delay of 75 to a delay of 750. Here's a screenshot of your current GUI.
Looking over your code, you extend a JFrame. You don't need to extend a JFrame. You're not changing any JFrame functionality. It's much simpler to use a JFrame. This leads to one of my Java rules.
Don't extend a Swing component, or any Java class, unless you intend
to override one or more of the class methods.
You do extend a JPanel. That's fine because you override the paintComponent method.
Finally, your JPanel class is doing too much work. You also make heavy use of static fields. Even though you'll only create one JPanel, it's a good habit to treat every class as if you will create multiple instances of the class. This creates fewer problems for yourself down the road.
You have the right idea, creating three classes.
So let's rework your code, using some basic patterns and Swing best practices. At this time, I don't know how many classes we'll wind up creating.
Explanation
When I write a Swing GUI, I use the model–view–controller (MVC) pattern. The name implies that you create a model first, then the view, then the controller(s).
An application model consists of one or more plain Java getter/setter classes.
A view consists of a JFrame, one or more JPanels, and any other necessary Swing components.
The controller consists of one or more Actions or ActionListeners. In Swing, there's usually not one controller to "rule them all".
To summarize:
The view reads information from the model
The view does not update the model
The controllers update the model and repaint/revalidate your view.
Model
I created two model classes, SnakeModel and Snake.
The SnakeModel class is a plain Java getter/setter class that holds one Snake instance, the apple eaten count, the apple location, the size of the game area, and a couple of booleans. One boolean indicates whether or not the game loop is running and the other boolean indicates whether or not the game is over.
The game area uses a java.awt.Dimension to hold the width and height of the game area. The width and the height do not have to have the same value. The game area can be rectangular.
The game area is measured in units. In the view, I convert the units into pixels. That's the opposite of what you did. If you want to change the game area, all you have to do is change the dimensions in the SnakeModel class. Everything in the view is based on the game area dimension.
The Snake class holds a java.util.List of java.awt.Point objects and a char direction. A java.awt.Point object holds an X and Y value. Since we're dealing with objects, rather than int values, we have to be careful to clone the object when we want a new Point.
View
All Swing applications must start with a call to the SwingUtilities invokeLater method. This method ensures that the Swing components are created and executed on the Event Dispatch Thread.
I created a JFrame, a drawing JPanel, and a separate button JPanel. Generally, it's not a good idea to add Swing components to a drawing JPanel. By creating a separate button JPanel, I get the added feature of a "Start Game" button at almost no extra cost. The button is disabled while the game is running.
The JFrame methods must be called in a specific order. The setVisible method must be called last.
I made the drawing JPanel more complicated by adding a separate area for the score.
I made the drawing JPanel less complicated by only drawing the state of the game, based on the application model. Period. Nothing else.
I limited the random colors to the white end of the color spectrum to maintain the contrast between the snake and the drawing JPanel background.
I used key bindings instead of a key listener. One advantage is that the drawing JPanel doesn't have to be in focus. Since I have a separate button JPanel, the drawing JPanel doesn't have focus.
Another advantage is that I can add the WASD keys with four lines of additional code.
One disadvantage is that the key bindings code looks more complicated than a key listener. Once you've coded a few key bindings, you'll appreciate the advantages.
Controller
I created three controller classes, ButtonListener, TimerListener, and MovementAction.
The ButtonListener class implements ActionListener. The ButtonListener class initializes the game model and restarts the timer.
The TimerListener class implements ActionListener. The TimerListener class is the game loop. This class moves the snake, checks to see if the apple is eaten, checks to see if the snake has moved outside the game area or touched itself, and repaints the drawing JPanel. I used your code as a model for the code in this class.
The MovementAction class extends AbstractAction. The AbstractAction class implements Action. This class changes the direction of the snake, based on the key presses.
I create four instances of the MovementAction class, one for each direction. This makes the actionPerformed method of the class much simpler.
Images
Here's what the revised GUI looks like when you start the game.
Here's the revised GUI during the game.
Here's the revised GUI when the game is over.
Code
Here's the complete runnable code. I made all the additional classes inner classes so I could post this code as one block.
You should put the separate classes in separate files.
When setting up a Swing GUI project, I create separate packages for the model, view, and controller. This helps me keep the code organized.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.BorderFactory;
import javax.swing.InputMap;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class SnakeGame implements Runnable {
public static void main(String arg[]) {
SwingUtilities.invokeLater(new SnakeGame());
}
private final GamePanel gamePanel;
private final JButton restartButton;
private final SnakeModel model;
public SnakeGame() {
this.model = new SnakeModel();
this.restartButton = new JButton("Start Game");
this.gamePanel = new GamePanel(model);
}
#Override
public void run() {
JFrame frame = new JFrame("Snake");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(gamePanel, BorderLayout.CENTER);
frame.add(createButtonPanel(), BorderLayout.SOUTH);
frame.pack();
frame.setResizable(false);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private JPanel createButtonPanel() {
JPanel panel = new JPanel();
panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
panel.setBackground(Color.black);
restartButton.addActionListener(new ButtonListener(this, model));
panel.add(restartButton);
return panel;
}
public JButton getRestartButton() {
return restartButton;
}
public void repaint() {
gamePanel.repaint();
}
public class GamePanel extends JPanel {
private static final long serialVersionUID = 1L;
private final int margin, scoreAreaHeight, unitSize;
private final Random random;
private final SnakeModel model;
public GamePanel(SnakeModel model) {
this.model = model;
this.margin = 10;
this.unitSize = 25;
this.scoreAreaHeight = 36 + margin;
this.random = new Random();
this.setBackground(Color.black);
Dimension gameArea = model.getGameArea();
int width = gameArea.width * unitSize + 2 * margin;
int height = gameArea.height * unitSize + 2 * margin + scoreAreaHeight;
this.setPreferredSize(new Dimension(width, height));
setKeyBindings();
}
private void setKeyBindings() {
InputMap inputMap = this.getInputMap(JPanel.WHEN_IN_FOCUSED_WINDOW);
ActionMap actionMap = this.getActionMap();
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "up");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0), "down");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), "left");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0), "right");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_W, 0), "up");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0), "down");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0), "left");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_D, 0), "right");
actionMap.put("up", new MovementAction(model, 'U', 'D'));
actionMap.put("down", new MovementAction(model, 'D', 'U'));
actionMap.put("left", new MovementAction(model, 'L', 'R'));
actionMap.put("right", new MovementAction(model, 'R', 'L'));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Dimension gameArea = model.getGameArea();
drawHorizontalGridLines(g, gameArea);
drawVerticalGridLines(g, gameArea);
drawSnake(g);
drawScore(g, gameArea);
if (model.isGameOver) {
drawGameOver(g, gameArea);
} else {
drawApple(g);
}
}
private void drawHorizontalGridLines(Graphics g, Dimension gameArea) {
int y1 = scoreAreaHeight + margin;
int y2 = y1 + gameArea.height * unitSize;
int x = margin;
for (int index = 0; index <= gameArea.width; index++) {
g.drawLine(x, y1, x, y2);
x += unitSize;
}
}
private void drawVerticalGridLines(Graphics g, Dimension gameArea) {
int x1 = margin;
int x2 = x1 + gameArea.width * unitSize;
int y = margin + scoreAreaHeight;
for (int index = 0; index <= gameArea.height; index++) {
g.drawLine(x1, y, x2, y);
y += unitSize;
}
}
private void drawApple(Graphics g) {
// Draw apple
g.setColor(Color.red);
Point point = model.getAppleLocation();
if (point != null) {
int a = point.x * unitSize + margin + 1;
int b = point.y * unitSize + margin + scoreAreaHeight + 1;
g.fillOval(a, b, unitSize - 2, unitSize - 2);
}
}
private void drawScore(Graphics g, Dimension gameArea) {
g.setColor(Color.red);
g.setFont(new Font("Ink Free", Font.BOLD, 36));
FontMetrics metrics = getFontMetrics(g.getFont());
int width = 2 * margin + gameArea.width * unitSize;
String text = "SCORE: " + model.getApplesEaten();
int textWidth = metrics.stringWidth(text);
g.drawString(text, (width - textWidth) / 2, g.getFont().getSize());
}
private void drawSnake(Graphics g) {
// Draw snake
Snake snake = model.getSnake();
List<Point> cells = snake.getCells();
Point cell = cells.get(0);
drawSnakeCell(g, cell, Color.green);
for (int index = 1; index < cells.size(); index++) {
// Color color = new Color(45, 180, 0);
// random color
Color color = new Color(getColorValue(), getColorValue(),
getColorValue());
cell = cells.get(index);
drawSnakeCell(g, cell, color);
}
}
private void drawSnakeCell(Graphics g, Point point, Color color) {
int x = margin + point.x * unitSize;
int y = margin + scoreAreaHeight + point.y * unitSize;
if (point.y >= 0) {
g.setColor(color);
g.fillRect(x, y, unitSize, unitSize);
}
}
private int getColorValue() {
// White has color values of 255
return random.nextInt(64) + 191;
}
private void drawGameOver(Graphics g, Dimension gameArea) {
g.setColor(Color.red);
g.setFont(new Font("Ink Free", Font.BOLD, 72));
FontMetrics metrics = getFontMetrics(g.getFont());
String text = "Game Over";
int textWidth = metrics.stringWidth(text);
g.drawString(text, (getWidth() - textWidth) / 2, getHeight() / 2);
}
}
public class ButtonListener implements ActionListener {
private final int delay;
private final SnakeGame view;
private final SnakeModel model;
private final Timer timer;
public ButtonListener(SnakeGame view, SnakeModel model) {
this.view = view;
this.model = model;
this.delay = 750;
this.timer = new Timer(delay, new TimerListener(view, model));
}
#Override
public void actionPerformed(ActionEvent event) {
JButton button = (JButton) event.getSource();
String text = button.getText();
if (text.equals("Start Game")) {
button.setText("Restart Game");
}
button.setEnabled(false);
model.initialize();
timer.restart();
}
}
public class TimerListener implements ActionListener {
private final SnakeGame view;
private final SnakeModel model;
public TimerListener(SnakeGame view, SnakeModel model) {
this.view = view;
this.model = model;
}
#Override
public void actionPerformed(ActionEvent event) {
moveSnake();
checkApple();
model.checkCollisions();
if (model.isGameOver()) {
Timer timer = (Timer) event.getSource();
timer.stop();
model.setRunning(false);
view.getRestartButton().setEnabled(true);
}
view.repaint();
}
private void moveSnake() {
Snake snake = model.getSnake();
Point head = (Point) snake.getHead().clone();
switch (snake.getDirection()) {
case 'U':
head.y--;
break;
case 'D':
head.y++;
break;
case 'L':
head.x--;
break;
case 'R':
head.x++;
break;
}
snake.removeTail();
snake.addHead(head);
// System.out.println(Arrays.toString(cells.toArray()));
}
private void checkApple() {
Point appleLocation = model.getAppleLocation();
Snake snake = model.getSnake();
Point head = snake.getHead();
Point tail = (Point) snake.getTail().clone();
if (head.x == appleLocation.x && head.y == appleLocation.y) {
model.incrementApplesEaten();
snake.addTail(tail);
model.generateRandomAppleLocation();
}
}
}
public class MovementAction extends AbstractAction {
private static final long serialVersionUID = 1L;
private final char newDirection, oppositeDirection;
private final SnakeModel model;
public MovementAction(SnakeModel model, char newDirection,
char oppositeDirection) {
this.model = model;
this.newDirection = newDirection;
this.oppositeDirection = oppositeDirection;
}
#Override
public void actionPerformed(ActionEvent event) {
if (model.isRunning()) {
Snake snake = model.getSnake();
char direction = snake.getDirection();
if (direction != oppositeDirection && direction != newDirection) {
snake.setDirection(newDirection);
// System.out.println("New direction: " + newDirection);
}
}
}
}
public class SnakeModel {
private boolean isGameOver, isRunning;
private int applesEaten;
private Dimension gameArea;
private Point appleLocation;
private Random random;
private Snake snake;
public SnakeModel() {
this.random = new Random();
this.snake = new Snake();
this.gameArea = new Dimension(24, 24);
}
public void initialize() {
this.isRunning = true;
this.isGameOver = false;
this.snake.initialize();
this.applesEaten = 0;
Point point = generateRandomAppleLocation();
// Make sure first apple isn't under snake
int y = (point.y == 0) ? 1 : point.y;
this.appleLocation = new Point(point.x, y);
}
public void checkCollisions() {
Point head = snake.getHead();
// Check for snake going out of the game area
if (head.x < 0 || head.x > gameArea.width) {
isGameOver = true;
return;
}
if (head.y < 0 || head.y > gameArea.height) {
isGameOver = true;
return;
}
// Check for snake touching itself
List<Point> cells = snake.getCells();
for (int index = 1; index < cells.size(); index++) {
Point cell = cells.get(index);
if (head.x == cell.x && head.y == cell.y) {
isGameOver = true;
return;
}
}
}
public Point generateRandomAppleLocation() {
int x = random.nextInt(gameArea.width);
int y = random.nextInt(gameArea.height);
this.appleLocation = new Point(x, y);
return getAppleLocation();
}
public void incrementApplesEaten() {
this.applesEaten++;
}
public boolean isRunning() {
return isRunning;
}
public void setRunning(boolean isRunning) {
this.isRunning = isRunning;
}
public boolean isGameOver() {
return isGameOver;
}
public void setGameOver(boolean isGameOver) {
this.isGameOver = isGameOver;
}
public Dimension getGameArea() {
return gameArea;
}
public int getApplesEaten() {
return applesEaten;
}
public Point getAppleLocation() {
return appleLocation;
}
public Snake getSnake() {
return snake;
}
}
public class Snake {
private char direction;
private List<Point> cells;
public Snake() {
this.cells = new ArrayList<>();
initialize();
}
public void initialize() {
this.direction = 'R';
cells.clear();
for (int x = 5; x >= 0; x--) {
cells.add(new Point(x, 0));
}
}
public void addHead(Point head) {
cells.add(0, head);
}
public void addTail(Point tail) {
cells.add(tail);
}
public void removeTail() {
cells.remove(cells.size() - 1);
}
public Point getHead() {
return cells.get(0);
}
public Point getTail() {
return cells.get(cells.size() - 1);
}
public char getDirection() {
return direction;
}
public void setDirection(char direction) {
this.direction = direction;
}
public List<Point> getCells() {
return cells;
}
}
}
I don't know what I did, or what went wrong, but a change I made at some point in the last while has made my JPanel completely invisible. The JFrame it's nested in still changes in size to house it, and I can still toggle the content in the combobox.
In my desperation, I tried replacing the content of the SnakeSettingsPanel class with a single button, but the same thing happened - completely invisible, yet I can still interact with it. I figured it might be a computer error, so I tried restarting, but still nothing. When I tried adding a button to the frame outside of the JPanel, it worked just fine. What am I doing wrong?
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class SnakeSettingsPanel extends JPanel {
public boolean quit = false;
public boolean play = false;
public int width = 20;
public int height = 15;
public Speed speed = Speed.SLOW;
public JTextField wField;
public JTextField hField;
public JComboBox<Speed> sField;
public static void main(String[] args) {
JFrame jf = new JFrame();
jf.setTitle("Snake");
SnakeSettingsPanel settings = new SnakeSettingsPanel();
jf.add(settings);
jf.pack();
jf.setVisible(true);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public SnakeSettingsPanel() {
setLayout(new GridBagLayout());
// #author Create our labels.
JLabel wLabel = new JLabel("Width:");
JLabel hLabel = new JLabel("Height:");
JLabel sLabel = new JLabel("Speed:");
GridBagConstraints p = new GridBagConstraints();
p.gridx = 0;
p.gridy = 0;
p.insets = new Insets(10, 10, 10, 10);
// #author Create the buttons, and add listeners
JButton y = new JButton("Play");
JButton n = new JButton("Quit");
y.addActionListener(new PlayListener());
n.addActionListener(new QuitListener());
// #author Create text fields for height/width
wField = new JTextField(15);
wField.setText("20");
hField = new JTextField(15);
hField.setText("15");
// #author Creates a combobox for selecting speed.
Speed[] speeds = {Speed.SLOW, Speed.MEDIUM, Speed.FAST};
sField = new JComboBox<Speed>(speeds);
// #author Stitch everything into the panel.
add(wLabel, p);
p.gridx = 1;
add(wField, p);
p.gridx = 0;
p.gridy = 1;
add(hLabel, p);
p.gridx = 1;
add(hField, p);
p.gridx = 0;
p.gridy = 2;
add(sLabel, p);
p.gridx = 1;
add(sField, p);
p.gridx = 0;
p.gridy = 3;
add(y, p);
p.gridx = 1;
add(n, p);
setVisible(true);
}
public boolean getPlay() {
return play;
}
public boolean getQuit() {
return quit;
}
// #author Returns all settings as a SnakeSettings object
public SnakeSettings getSettings() {
return new SnakeSettings(width, height, speed);
}
public int getWidth() {
return width;
}
public int getHeight() {
return height;
}
public Speed getSpeed() {
return speed;
}
// #author Sends out the word to start a new game.
public class PlayListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
quit = false;
play = true;
width = Integer.parseInt(wField.getText());
height = Integer.parseInt(hField.getText());
speed = (Speed) sField.getSelectedItem();
}
}
// #author Sends out the word to shut down the program.
public class QuitListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
quit = true;
play = false;
}
}
}
Let this be a lesson on why you should avoid mixing Model (your application's data) with View (how it is displayed). Your SnakeSettingsPanel is currently both.
As Model, it contains 3 important fields: width, height, and speed.
As View, it is a full JPanel. JPanels have a lot of fields which you should avoid touching directly. Including width and height, usually accessed via getHeight and getWidth -- which you are overwriting with a version that always returns the same built-in values of 20 and 15 (until the user changes those values through a UI that they cannot see).
The fast fix is to rename your current getWidth() and getHeight() to avoid clashing with the built-in getWidth() and getHeight() methods of the parent JPanel class. Call them getMyWidth(), getMyHeight(), and suddenly everything works.
The better fix is to remove those fields and methods entirely, and store your own model attributes in a SnakeSettings attribute. Update it when the user clicks on play, and return it when it is requested via getSettings(). Less code for you, less chance of accidental name clashes with your parent JPanel class. This would look like:
// SnakeSettingsPanel, before
public int width = 20;
public int height = 15;
public Speed speed = Speed.SLOW;
public int getWidth() { // <-- clashes with superclass
return width;
}
public int getHeight() { // <-- clashes with superclass
return height;
}
public Speed getSpeed() {
return speed;
}
public SnakeSettings getSettings() {
return new SnakeSettings(width, height, speed);
}
// SnakeSettingsPanel, after
SnakeSettings settings = new SnakeSettings();
public SnakeSettings getSettings() {
return settings;
}
I am trying to add a thing like this in my music player application in swing.
I tried to add a rectangle to BorderLayout.SOUTH, but it never appeared on screen. Here is what I did:
public class MyDrawPanel extends JPanel {
#Override
public void paintComponent(Graphics g) {
g.setColor(Color.GREEN);
g.fillRect(200,200,200,200);
}
public static void main(String[] args) {
JFrame frame = new JFrame();
MyDrawPanel a = new MyDrawPanel();
frame.getContentPane().add(BorderLayout.SOUTH,a);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(1000,1000);
frame.setVisible(true);
}
}
I just did not try 200,200,200,200, but I tried a lot of values, even with the help of a for loop, but it never appeared on screen. If I used CENTER instead of SOUTH it appeared. I read the documentation to check how fillRect works, but it simply said it added x+width and y+height. The point (0,0) is the top left corner. I checked that by adding a rectangle to CENTER layout. How cam I do it?
I did not share the output, because it was just a blank screen.
The values you give to fillRect are wrong. The first two are the top left corner's coordinates, relative to the component you're painting in; in your case the MyDrawPanel. With the code you posted, this drawing area is outside of the container the panel is placed in. You want to do
g.fillRect(0,0,200,200);
A note: You usually want to call frame.pack() after you've finished adding all components, so it can layout itself. In your case, this results in a tiny window because the system doesn't know how large it should be. You probably want to add a method
public Dimension getPreferredSize() {
System.out.println("getting pref size");
return new Dimension(200, 200);
}
to ensure it's always large enough to draw the full rectangle.
Also, you should call frame.getContentPane().setLayout(new BorderLayout()) before. You can print it out without setting it to see it is not the default. EDIT: As VGR points out, the documentation says that it is in fact a BorderLayout. I cannot confirm that is the case - it is in fact a RootLayout. That seems to behave like a BorderLayout though.
I thought this might make a quick little project. Here's the level meter I came up with.
The important parts are the DrawingPanel and the LevelMeterModel. The DrawingPanel takes the information from the LevelMeterModel and paints the bars on a JPanel.
The LevelMeterModel is an int array of levels, a minimum level, and a maximum level. The maximum level could be calculated, but I assumed music has a certain volume and frequency range.
The JFrame holds the DrawingPanel. A Swing Timer varies the levels somewhat randomly. The random numbers are in a small range so the bar heights don't change abruptly.
Here's the complete runnable code.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class LevelMeterGUI implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new LevelMeterGUI());
}
private final DrawingPanel drawingPanel;
private final LevelMeterModel model;
public LevelMeterGUI() {
this.model = new LevelMeterModel();
this.drawingPanel = new DrawingPanel(model);
}
#Override
public void run() {
JFrame frame = new JFrame("Level Meter GUI");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(drawingPanel, BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
System.out.println("Frame size: " + frame.getSize());
Timer timer = new Timer(250, new ActionListener() {
#Override
public void actionPerformed(ActionEvent event) {
model.setRandomLevels();
drawingPanel.repaint();
}
});
timer.start();
}
public class DrawingPanel extends JPanel {
private static final long serialVersionUID = 1L;
private final int drawingWidth, drawingHeight, margin, rows;
private final Dimension barDimension;
private final LevelMeterModel model;
public DrawingPanel(LevelMeterModel model) {
this.model = model;
this.margin = 10;
this.rows = 20;
this.barDimension = new Dimension(50, 10);
int columns = model.getLevels().length;
drawingWidth = columns * barDimension.width + (columns + 1) * margin;
drawingHeight = rows * barDimension.height + (rows + 1) * margin;
this.setBackground(Color.WHITE);
this.setPreferredSize(new Dimension(drawingWidth, drawingHeight));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
int maximum = model.getMaximumLevel();
double increment = (double) maximum / rows;
int peak = rows * 75 / 100;
int x = margin;
for (int level : model.getLevels()) {
int steps = (int) Math.round((double) level / increment);
int y = drawingHeight - margin - barDimension.height;
for (int index = 0; index < steps; index++) {
if (index < peak) {
g.setColor(Color.GREEN);
} else {
g.setColor(Color.RED);
}
g.fillRect(x, y, barDimension.width, barDimension.height);
y = y - margin - barDimension.height;
}
x += margin + barDimension.width;
}
}
}
public class LevelMeterModel {
private final int minimumLevel, maximumLevel;
private int[] levels;
private final Random random;
public LevelMeterModel() {
this.minimumLevel = 100;
this.maximumLevel = 999;
this.levels = new int[8];
this.random = new Random();
setRandomLevels();
}
public void setRandomLevels() {
for (int index = 0; index < levels.length; index++) {
levels[index] = getRandomLevel(levels[index]);
}
}
private int getRandomLevel(int level) {
if (level == 0) {
return random.nextInt(maximumLevel - minimumLevel) + minimumLevel;
} else {
int minimum = Math.max(level * 90 / 100, minimumLevel);
int maximum = Math.min(level * 110 / 100, maximumLevel);
return random.nextInt(maximum - minimum) + minimum;
}
}
public int[] getLevels() {
return levels;
}
public int getMinimumLevel() {
return minimumLevel;
}
public int getMaximumLevel() {
return maximumLevel;
}
}
}
I Think this is a Timer issue, first time ive used them and i feel like im doing it wrong.
I have a method that for testings sake, input 6 images and with the help of a timer paints them to a JPanel:
private void drawDice(Graphics2D g2d) throws IOException, InterruptedException {
image = ImageIO.read(getClass().getResourceAsStream("/1.png"));
m_dice.add(image);
image = ImageIO.read(getClass().getResourceAsStream("/2.png"));
m_dice.add(image);
image = ImageIO.read(getClass().getResourceAsStream("/3.png"));
m_dice.add(image);
image = ImageIO.read(getClass().getResourceAsStream("/4.png"));
m_dice.add(image);
image = ImageIO.read(getClass().getResourceAsStream("/5.png"));
m_dice.add(image);
image = ImageIO.read(getClass().getResourceAsStream("/6.png"));
m_dice.add(image);
time.start();
for(int i = 0; i < m_dice.size(); i++){
g2d.drawImage(m_dice.get(i), 700, 400, null, null);
repaint();
}
time.stop();
}
Timer time = new Timer(1000,this); < at the top of the class
The desired output is that all 6 dice images are shown at one second intervals but only "6.png" shows up.
thank you.
I think that you may be unclear on how a Timer works. Suggestions:
First and foremost -- get rid of the for loop since the Timer's code will replace this.
Next, if this is being called from paintComponent or other painting method, don't. You never want to read images in from a painting method as that will slow down the method and thus slow down the perceived performance of your GUI, not a good thing.
Next, read all the images in once in your constructor and save them to an array or ArrayList of images or Icons. My own vote is an ArrayList<Icon> of ImageIcons.
Easiest way to swap images is to display ImageIcons in a JLabel and simply call setIcon(...) on the JLabel, passing in the newest icon.
Next in your Timer's ActionListener, have a counter int variable that is initialized to 0.
In the ActionListener's actionPerformed method, increment the counter variable, and swap images.
Get the ImageIcon from the ArrayList using the counter as index.
Call setIcon(...) on your JLabel (again, this is all done inside of the actionPerformed method for the Timer).
If the counter is >= the number if icons in your ArrayList, 0 the counter. and call stop() on your Timer.
Something like:
int timerDelay = 1000;
new Timer(timerDelay, new ActionListener(){
int count = 0;
#Override
public void actionPerformed(ActionEvent e) {
if (count < IMAGE_COUNT) {
someLabel.setIcon(icons[count]);
count++;
} else {
// stop the timer
((Timer)e.getSource()).stop();
}
}
}).start();
For example, this program "rolls" a die by randomly swapping ImageIcons in a JLabel maxCount number of times:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class RollDice extends JPanel {
// nice public domain dice face images. All 6 images in one "sprite sheet" image.
private static final String IMG_PATH = "https://upload.wikimedia.org/"
+ "wikipedia/commons/4/4c/Dice.png";
private static final int TIMER_DELAY = 200;
private List<Icon> diceIcons = new ArrayList<>(); // list to hold dice face image icons
private JLabel diceLabel = new JLabel(); // jlabel to display images
private Timer diceTimer; // swing timer
public RollDice(BufferedImage img) {
// subdivide the sprite sheet into individual images
// use them to create ImageIcons
// and add them to my diceIcons ArrayList<Icon>.
double imgW = img.getWidth() / 3.0;
double imgH = img.getHeight() / 2.0;
for (int row = 0; row < 2; row++) {
int y = (int) (row * imgH);
for (int col = 0; col < 3; col++) {
int x = (int) (col * imgW);
BufferedImage subImg = img.getSubimage(x, y, (int)imgW, (int)imgH);
diceIcons.add(new ImageIcon(subImg));
}
}
// panel to hold roll dice button
JPanel btnPanel = new JPanel();
btnPanel.setOpaque(false);
btnPanel.add(new JButton(new RollDiceAction("Roll Dice")));
// set the JLabel's icon to the first one in the collection
diceLabel.setIcon(diceIcons.get(0));
setLayout(new BorderLayout());
setBackground(Color.WHITE);
add(diceLabel);
add(btnPanel, BorderLayout.PAGE_END);
}
public void rollDice() {
// if the timer's already running, exit this method
if (diceTimer != null && diceTimer.isRunning()) {
return;
}
// else create a new Timer and start it
diceTimer = new Timer(TIMER_DELAY, new TimerListener());
diceTimer.start();
}
// ActionListener for the Swing Timer
private class TimerListener implements ActionListener {
private int count = 0; // count how many times dice changes face
private final int maxCount = 20;
#Override
public void actionPerformed(ActionEvent e) {
// once there are max count changes, stop the timer
if (count >= maxCount) {
((Timer) e.getSource()).stop();
}
// get a random index from 0 to 5
int randomIndex = (int) (Math.random() * diceIcons.size());
// show that random number's dice face
diceLabel.setIcon(diceIcons.get(randomIndex));
count++; // increment the count
}
}
// ActionListener for our button
private class RollDiceAction extends AbstractAction {
public RollDiceAction(String name) {
super(name); // text to show in the button
}
#Override
public void actionPerformed(ActionEvent e) {
rollDice(); // simply call the roll dice method
}
}
private static void createAndShowGui(BufferedImage img) {
RollDice mainPanel = new RollDice(img);
JFrame frame = new JFrame("RollDice");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
try {
URL imgUrl = new URL(IMG_PATH);
final BufferedImage img = ImageIO.read(imgUrl);
SwingUtilities.invokeLater(() -> {
createAndShowGui(img);
});
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
}
}
I am beginner in java programming. We were given a task, to do some algorithms. I got Sierpinski Triangle. I had an idea to create a 2D array and store the values, 0 = white rectangle, 1 = blue rectangle. I had big trouble to draw it (never had any experience with swing/awt). I finally did it but on the end of the drawing there is weird visual bug. It is not ending but the lines are still continuing.
I have no idea why is it like that.
Here is my code:
Okno class that extends JPanel:
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package newpackage;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.util.Arrays;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
/**
*
* #author Juraj
*/
class Okno extends JPanel {
// value = 1 is blue rectangle, value 0 = white rectangle
public static int n = 500;
public static int[][] tabulka = new int[n][n]; //creating 2D array
public static void inicializaciaTabulky(){
for (int i = 0; i < n; i++) { // initialization of 2D array (first column and first row = 1)
tabulka[0][i] = 1;
tabulka[i][0] = 1;
}
}
// filling the rest of the array; if the cell above and cell to the left are the same value, e.g.
// value of 1 or 0, then it is 0, everything else is 1
public static void doplnenieTabulky() {
for (int i = 1; i < n; i++) {
for (int j = 1; j < n; j++) {
if (tabulka[i-1][j] == 1 && tabulka[i][j-1] == 1 ||
tabulka[i-1][j] == 0 && tabulka[i][j-1] == 0) {
tabulka[i][j] = 0;
} else {
tabulka[i][j] = 1;
}
}
}
}
// drawing rectangles; if the value is 1 = blue rectangle, value 0 = white rectangle
private void vykreslenie(Graphics g){
Graphics2D g2d = (Graphics2D) g;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
switch(tabulka[i][j]) {
case 0:
g.setColor(Color.white);
g.drawRect(i, j, 50, 50);
break;
case 1:
g.setColor(Color.blue);
g.drawRect(i, j, 50, 50);
break;
}
}
}
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
vykreslenie(g);
}
}
Trojuholnik class that extends JFrame:
public class Trojuholnik extends JFrame {
public Trojuholnik() {
initUI();
}
private void initUI() {
setSize(800, 600);
setTitle("Sierpinski Triangle");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
add(new Okno());
setLocationRelativeTo(rootPane);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
Trojuholnik trojuholnik = new Trojuholnik();
trojuholnik.setVisible(true);
Okno.inicializaciaTabulky();
Okno.doplnenieTabulky();
System.out.println(Arrays.deepToString(Okno.tabulka));
}
});
}
}
The current result looks like this:
First of all some basic suggestions:
Don't create a class that extends JFrame. You are not adding new functionality to the frame so you should just be adding your panel to a frame. So the basic code in your run() method should be something like:
JFrame frame = new JFrame();
frame.setTitle("Sierpinski Triangle");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( new Okno());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
Don't use static variables and methods in your Okno class. Just create a constructor for your class and initialize the array in the constructor.
When doing custom painting you should be overriding the getPreferredSize() method of you class to return the size of the component because each component should know its own size. Note how I changed the above code to use the pack() method. Now the frame will be resized properly. So you would add something like the following to your Okno class:
#Override
public Dimension getPreferredSize()
{
return new Dimension(500, 500);
}
Regarding the painting problem. I don't really know what the algorithm is doing, but I suspect that the problem is that your array has 500 values, but the painting of the Rectangle is using a size of 50, so effectively the size of your panel is 550x550 not 500x500 which causes the artifacts.
I think the solution is to simply draw with a rectangle size of (1, 1). At least the drawing looks the same to me.