I've been taking AP Computer Science this year as a sophomore in high school and we mainly cover material like loops, classes, methods, general CS logic, and some math stuff. I am missing what I really loved about coding in the first place, making games. Now every game I have made had some sort of way to manage it whether it was using timers in visual basic or a XNA plugin for c# that setup a update method for me. The problem is I have not learned how to do this for java in my course. I've read up a little on threads and implements runnable but i'm not really sure where I'm going with it.
Class 1
import java.awt.FlowLayout;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
public class GFXScreen extends JFrame
{
/**
* #param screenHeigth
* #param screenHeigth
* #param The file name of the image. Make sure to include the extension type also
* #param The title at the top of the running screen
* #param The height of the screen
* #param The width of the screen
*/
public GFXScreen(String fileName, String screenTitle, int screenHeight, int screenWidth)
{
setLayout(new FlowLayout());
image1 = new ImageIcon(getClass().getResource(fileName));
label1 = new JLabel(image1);
this.add(label1);
//Set up JFrame
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.setVisible(true);
this.setTitle(screenTitle);
this.setSize(screenWidth, screenHeight);
}
/**
* #param desired amount to move picture
*/
public void updatePic(int increment)
{
//update pos
label1.setBounds(label1.bounds().x, label1.bounds().y - increment,
label1.bounds().width, label1.bounds().height);
}
private ImageIcon image1;
private JLabel label1;
}
Class 2
public class MainClass implements Runnable {
public static void main(String[] args)
{
(new Thread(new MainClass())).start();
GFXScreen gfx = new GFXScreen("pixel_man.png", "pixel_Man", 1000, 1000);
}
public void run()
{
gfx.updatePic(1);
}
}
In this instance what I want to happen is, I want a picture that starts in the top to slowly move down smoothly to the bottom. How would i do this?
Suggestions:
Again, a Swing Timer works well for simple Swing animations or simple game loops. It may not be the greatest choice for complex or rigorous tame loops as its timing is not precise.
Most game loops will not be absolutely precise with time slices
And so your game model should take this into consideration and should note absolute time slices and use that information in its physics engine or animation.
If you must use background threading, do take care that most all Swing calls are made on the Swing event thread. To do otherwise will invite pernicious infrequent and difficult to debug program-ending exceptions. For more details on this, please read Concurrency in Swing.
I avoid using null layouts, except when animating components, as this will allow my animation engine to place the component absolutely.
When posting code here for us to test, it's best to avoid code that uses local images. Either have the code use an image easily available to all as a URL or create your own image in your code (see below for a simple example).
Your compiler should be complaining to you about your using deprecated methods, such as bounds(...), and more importantly, you should heed those complaints as they're there for a reason and suggest increased risk and danger if you use them. So don't use those methods, but instead check the Java API for better substitutes.
Just my own personal pet peeve -- please indicate that you've at least read our comments. No one likes putting effort and consideration into trying to help, only to be ignored. I almost didn't post this answer because of this.
For example:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import javax.swing.AbstractAction;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
#SuppressWarnings("serial")
public class GfxPanel extends JPanel {
private static final int BI_WIDTH = 26;
private static final int BI_HEIGHT = BI_WIDTH;
private static final int GAP = 6;
private static final Point INITIAL_LOCATION = new Point(0, 0);
private static final int TIMER_DELAY = 40;
public static final int STEP = 1;
private ImageIcon image1;
private JLabel label1;
private Point labelLocation = INITIAL_LOCATION;
private int prefW;
private int prefH;
private Timer timer;
public GfxPanel(int width, int height) {
// the only time I use null layouts is for component animation.
setLayout(null);
this.prefW = width;
this.prefH = height;
// My program creates its image so you can run it without an image file
image1 = new ImageIcon(createMyImage());
label1 = new JLabel(image1);
label1.setSize(label1.getPreferredSize());
label1.setLocation(labelLocation);
this.add(label1);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(prefW, prefH);
}
public void startAnimation() {
if (timer != null && timer.isRunning()) {
timer.stop();
}
labelLocation = INITIAL_LOCATION;
timer = new Timer(TIMER_DELAY, new TimerListener());
timer.start();
}
// My program creates its image so you can run it without an image file
private Image createMyImage() {
BufferedImage bi = new BufferedImage(BI_WIDTH, BI_HEIGHT,
BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = bi.createGraphics();
g2.setColor(Color.red);
g2.fillRect(0, 0, BI_WIDTH, BI_HEIGHT);
g2.setColor(Color.blue);
int x = GAP;
int y = x;
int width = BI_WIDTH - 2 * GAP;
int height = BI_HEIGHT - 2 * GAP;
g2.fillRect(x, y, width, height);
g2.dispose();
return bi;
}
private class TimerListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
int x = labelLocation.x + STEP;
int y = labelLocation.y + STEP;
labelLocation = new Point(x, y);
label1.setLocation(labelLocation);
repaint();
if (x + BI_WIDTH > getWidth() || y + BI_HEIGHT > getHeight()) {
System.out.println("Stopping Timer");
((Timer) e.getSource()).stop();
}
}
}
private static void createAndShowGui() {
final GfxPanel gfxPanel = new GfxPanel(900, 750);
JButton button = new JButton(new AbstractAction("Animate") {
#Override
public void actionPerformed(ActionEvent arg0) {
gfxPanel.startAnimation();
}
});
JPanel buttonPanel = new JPanel();
buttonPanel.add(button);
JFrame frame = new JFrame("GFXScreen");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(gfxPanel);
frame.getContentPane().add(buttonPanel, BorderLayout.PAGE_END);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
What I always use is an infinite loop that calls an update method each iteration, in that method, you would do whatever was required to update the state of the game or render a GUI.
Example
public static void main(String[] args){
// Initialise game
while(true){
updateGame();
}
}
public static void updateGame(){
// Update things here.
}
What I also do ,which is a little more complex, is create and interface called IUpdateListener and have certain classes that are specialised for a certain element of the game. I would example have an InputListener, an AIListener, each handling a certain element of game updating.
public interface IUpdateListener{
public void update();
}
public class Main{
public static ArrayList<IUpdateListener> listeners = new ArrayList<IUpdateListener>();
public static void main(String[] args){
listeners.add(new InputListener());
while(true){
for(IUpdateListener listener : listeners){
listener.update();
}
}
}
}
public class InputListener implements IUpdateListener{
public void update(){
// Handle user input here etc
}
}
Related
I am new to programming in Java, but I have coded in other languages. I've got a problem whereby I am unable to call my Paint() method which contains some drawing instructions. I want to be able to call it inside a timer function. The code's bellow:
package main;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.Timer;
import java.util.TimerTask;
import java.awt.Canvas;
import javax.swing.JPanel;
public class Player extends JPanel implements KeyListener, ActionListener{
// does the same as inheritiing methods and attributes from "JPanel" class type.
private static final long serialVersionUID = 1L;
private static long UUID;
// Time to set game-state values
#SuppressWarnings("unused")
private boolean isPlaying = false;
private int startingScore = 0;
#SuppressWarnings("unused")
private int currScore = startingScore;
// currScore should equal startingScore for correct start score when starting each game.
#SuppressWarnings("unused")
private int TotalBricks = 21;
private static Timer timer = new Timer();
private int delay = 5;
// Player Start Pos
private int PlayerX = 310;
private int PlayerY = 550; // TODO Change PlayerY Value
// Player Dimensions from Start Coords
private int PlayerMinX = PlayerX - 50;
private int PlayerMaxX = PlayerX + 50;
private int PlayerMinY = PlayerY - 4;
private int PlayerMaxY = PlayerY + 4;
// Ball Start Pos
#SuppressWarnings("unused")
private int BallX = 120;
#SuppressWarnings("unused")
private int BallY = 350;
// Ball Velocities
#SuppressWarnings("unused")
private int BallVelX = -1;
#SuppressWarnings("unused")
private int BallVelY = -2;
public Player(){
super();
this.setBackground(Color.white);
addKeyListener(this);
setFocusable(true);
setFocusTraversalKeysEnabled(false);
setVisible(true);
MyTimer();
//TODO Get the bricks to display on screen
}
public void MyTimer() {
TimerTask timerTask;
timerTask = new TimerTask() {
#Override
public void run() {
while (true) {
// TODO Get Paint() function working in here
}
}
};
timer.schedule(timerTask, 0, delay);
}
public void Paint(Graphics g){
// linear functions - colour precedes draw, can be overriden without affecting previous statements
// background
g.setColor(Color.black);
g.fillRect(1, 1, 692, 592);
// border of window
g.setColor(Color.yellow);
g.fillRect(0,0,3,592);
g.fillRect(0,0,692,3);
g.fillRect(691,0,3,592);
// no underside border
// paddle settings
g.setColor(Color.green);
g.fillRect(PlayerMinX, PlayerMinY, PlayerMaxX, PlayerMaxY);
//TODO Check if this works
// ball settings
g.setColor(Color.yellow);
g.fillRect(BallX, BallY, 20, 20);
}
public void actionPerformed(ActionEvent arg0) {
}
public void keyPressed(KeyEvent arg0) {
if (arg0.getKeyCode() == KeyEvent.VK_RIGHT)
{
}
else if (true){
}
}
public void keyReleased(KeyEvent arg0) {}
public void keyTyped(KeyEvent arg0) {}
}
Any help would be greatly appreciated. Also, any tips you guys could provide would also help. Thanks for any help you can provide in advance.
Custom painting is done by overriding paintComponent(...) not paint(...). You also need to invoke super.paintComponent(g) as the first statement to make sure the background get painted.
Java is case sensitive, so you need to make sure you override the proper method. You should always use #Override on the line before the method you override. If you make a typing error the compiler will tell you.
You should be using a Swing Timer for animation. Updates to Swing components should be done on the Event Dispatch Thread (EDT). The Swing Timer will automatically execute the code on the EDT.
Don't use a while (true) loop in the Timer. The point of using a Timer is that the Timer becomes the loop. You just execute your code every time the Timer fires.
In the ActionListener of your Timer you change the value of your variables to provide the animation and then you invoke repaint() which will cause your panel to be repainted.
Variable names should NOT start with an upper case character. Notice how the forums highlights your variable names because it thinks they are class names. This is confusing. Learn Java conventions and follow them.
Read the Swing Tutorial for Swing basics. There are section on a) Concurrency in Swing b) How to Use Swing Timers c) Custom Painting.
I testing to implement graphics into MVC structure but Im a bit stuck. Here is what I got so far. For now I just want to get the red ball to bounce back and forth. And use the button start to start the thread and button stop to stop the thread that runs the GameLoop in the controller.
But I think Im mixing this up a bit. Would very much appreciate some feedback!
Heres what I got so far:
GameModell
suppose to controll the bouncing. If the location of the ball is under 40 px or above 80 px - multiply the locationX with -1 to make the ball change direction
GameView
Here Im putting the labels on a JFrame. I also want to display the buttons start and stop to controll the thread but I guess they are hidden by the JPanel in TheGraphics class
GameController
Starts and stops the thread with ActionListeners. Contains the GameLoop
TheGraphics
Paints the ball and controll the direction
I guess I got a lot of thing that are all wrong but this is the best I can do at the moment. Would very much apreciate some help!
Thanks!
MAIN:
public class MVCgame {
public static void main(String[] args) {
GameModel gm = new GameModel();
GameView gv = new GameView();
GameController gc = new GameController(gm, gv);
}
}
MODEL:
public class GameModel {
private int multi = 1;
public void setMulti(int locX) {
if(locX < 40 || locX > 80) {
multi = multi * -1;
}
}
public int multi() {
return multi;
}
}
VIEW:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class GameView extends JFrame {
private JPanel jp = new JPanel();
private JButton start = new JButton("Start");
private JButton stop = new JButton("Stop");
TheGraphics gr = new TheGraphics();
public GameView() {
add(jp);
add(gr);
jp.add(start);
jp.add(stop);
setSize(250, 250);
setVisible(true);
}
public void addListener(ActionListener theListener) {
start.addActionListener(theListener);
stop.addActionListener(theListener);
}
public JButton getStart() {
return start;
}
public JButton getStop() {
return stop;
}
// GUESS I SHOULD PUT THIS IN THE VIEW???
public void paintEllipse(Graphics theG) {
Graphics2D g2d = (Graphics2D) theG;
g2d.setColor(new Color(255, 0, 0));
g2d.fillOval(0, 0, 10, 10);
}
}
CONTROLLER:
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class GameController implements Runnable {
GameView gv;
GameModel gm;
private Thread thread;
private boolean running = false;
public GameController(GameModel gm, GameView gv) {
this.gv = gv;
this.gm = gm;
gv.addListener(theListener);
start();
}
ActionListener theListener = new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (e.getSource() == gv.getStart()) {
start();
System.out.println("PLAY = ");
} else if (e.getSource() == gv.getStop()) {
stop();
System.out.println("STOP = ");
}
}
};
public synchronized void start() {
thread = new Thread(this);
thread.start();
running = true;
}
public synchronized void stop() {
thread.interrupt();
running = false;
}
// GameLoop
public void run() {
long lastTime = System.nanoTime();
double amountOfTicks = 60.0;
double ns = 1000000000 / amountOfTicks;
double delta = 0;
long timer = System.currentTimeMillis();
int frames = 0;
while (running) {
long now = System.nanoTime();
delta += (now - lastTime) / ns;
lastTime = now;
while (delta >= 10) {
// tick();
delta--;
// repainting the graphics
gv.gr.drawer();
gm.setMulti(gv.gr.drawer());
System.out.println("gv.gr.drawer() = " + gv.gr.drawer() + " gm.multi() " + gm.multi());
// I want to use this value in the model to change the direction
}
if (running) {
}
frames++;
if (System.currentTimeMillis() - timer > 1000) {
timer += 1000;
System.out.println("FPS: " + frames);
frames = 0;
}
}
}
}
THE GRAPHICS:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JPanel;
public class TheGraphics extends JPanel {
private int locX = 40;
public TheGraphics() {
}
public int drawer() {
locX++;
repaint();
return locX;
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(new Color(255, 0, 0));
g2d.fillOval(locX, 30, 10, 10);
}
}
GameModell suppose to controll the bouncing. If the location of the ball is under 40 px or above 80 px - multiply the locationX with -1 to make the ball change direction
public void setMulti(int locX) {
if(locX < 40 || locX > 80) {
multi = multi * -1;
}
}
Really bad idea. You should always check position and direction (sign(speed)). Otherwise, your object might get stuck out of bounds always changing direction without moving from place forever.
Apart from this, using the MVC concept is overkill in my eyes and shouldn't be used in such a small project nor in a game. In a game, you should more or less put all three together. Of course you can, but the advantages and disadvantages of the MVC concept don't fit the needs of a game in many ways (except for the GUI, perhaps).
Your main loop might look something like this (you kind of did this already, but why is the tick() commented out in your code?):
while (running) {
update(); // Update all game objects
paint(); // Paint them all
}
Each game object will have its own update() and paint() implementation. You absolutely need to separate the logic of update and paint, even if they are in the same class. So this one:
public int drawer() {
locX++;
repaint();
return locX;
}
is an absolute no-go.
Edit: (Referring your update answer)
You are using the method location() for different purposes. According to the Java name convention, you should rename it getLocation() and setLocation() depending on the use to clarify the code.
(Even if this is not really MVC anymore, I'd let GameFrame implement ActionListener instead of specifying it as variable of GameController.)
One thing you should really change is this one:
private int locX = 0;
public void location(int loc) {
this.locX = (int) loc;
}
Basically, you are duplicating the location value every frame and create unused redundant data. Another problem is, that this might work fine for only one variable, but what if you add more than the position to your model later on? Instead TheGraphics has to render on an instance of the data model, not its values. As long you are using one GameModel
private GameModel model; // set value once at initialisation
and rendering its values in paintComponent will work fine, but if you want to add more than one GameModel (handling GameModel more like a GameObjectModel), you will need to pass it as parameter in the paint method.
public void update() {
repaint();
}
Remove it and try getting around without. A method called from one place forwarding to a different method is a bad idea most of the time, especially if it obfuscates the functionality with a different name.
gv.gr.update();
gv.gr.location(gm.location());
You are first repainting your image and then setting the location? Basically, your game runs one frame behind all the time. Swap that order.
gv.gr.location(gm.location());
gv.gr.repaint();
Will be fine (I already said about location()).
I am learning java swing and am having trouble with the following program. It creates a small frame with a quit button at top. The objective is to display coordinates wherever the mouse is clicked. When I click the mouse 2 unwanted things are happening:
the quit button is overridden by the mouse clicks and it no longer responds (instead of responding to event and quitting, it displays coordinates on top of the quit button).
when I click at a new location, the coordinates from the old location persist.
I used removeAll() and revalidate() before doing repaint() based on this discussion but that has not helped. This code is taken from here and the code to says to research online documentation for why this is happening.
Any pointers?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.Color;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.BorderLayout;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JLabel;
public class QuitCoordinateTest {
public static void main(String[] args){
GUI gui = new GUI();
}
}
class MyFrame extends JFrame implements ActionListener{
int clickX;
int clickY;
public void paint(Graphics g){
g.drawString("" + clickX + ", " + clickY, clickX, clickY);
}
public void actionPerformed(ActionEvent e){
System.exit(0);
}
}
//=======================================================//
class GUI extends MyFrame {
JButton quitButton = new JButton("Quit");
public GUI(){
MyFrame displayWindow = new MyFrame();
displayWindow.setTitle("Title");
/*
JPanel buttonPanel = new JPanel();
buttonPanel.add(quitButton);
displayWindow.getContentPane().add(buttonPanel,BorderLayout.NORTH);
JPanel textPanel = new JPanel();
*/
displayWindow.getContentPane().add(quitButton,BorderLayout.NORTH);
quitButton.addActionListener(displayWindow);
displayWindow.setSize(201,201);
displayWindow.setVisible(true);
// displayWindow.pack();
displayWindow.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
displayWindow.addMouseListener(new MouseProc(displayWindow));
}//end constructor
}//end class GUI definition
//=======================================================//
//This listener class monitors for mouse presses and
// displays the coordinates of the mouse pointer when the
// mouse is pressed on the source object.
class MouseProc extends MouseAdapter{
MyFrame refToWin;
MouseProc(MyFrame inWin){
refToWin = inWin;
}
//Override the mousePressed method to determine and
// display the coordinates when the mouse is pressed.
public void mousePressed(MouseEvent e){
refToWin.removeAll();
refToWin.clickX = e.getX();
refToWin.clickY = e.getY();
//Force the JFrame object to be repainted in order to
// display the coordinate information.
refToWin.removeAll();
refToWin.validate();
refToWin.repaint();
}
}
repaint() is working fine.
Avoid drawing directly on the JFrame.
Instead draw in the protected void paintComponent(Graphics g) method override of a JPanel that is then displayed in your JFrame.
Be sure to call the super's paintComponent(g) method inside of your paintComponent override -- this will erase the old images and is the reason for one of your problems.
Use reasonable comments in your code. Too many comments and too much text distracts and makes understanding your code harder, not easier.
Calling removeAll() on your JFrame will do just that -- remove all components including your button. Why are you calling this? Are you sure that you want to call this method?
A minor nitpick -- you'll want to avoid directly setting the fields of another class, such as your clickX and clickY fields. Instead, make them private, and only allow outside classes to modify them through public methods. While it may not matter much for this small program, it will matter greatly when you start scaling up your programming and create large programs with complex interactions. The key to success here will be to limit and control all communication between classes to avoid hard to detect side effects.
For example, something like...
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
String str = String.format("[%d, %d]", clickX, clickY);
g.drawString(str, clickX, clickY);
}
public int getClickX() {
return clickX;
}
public void setClickX(int clickX) {
this.clickX = clickX;
}
public int getClickY() {
return clickY;
}
public void setClickY(int clickY) {
this.clickY = clickY;
}
For example
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.*;
#SuppressWarnings("serial")
public class DetectClicks extends JPanel {
private static final int PREF_W = 800;
private static final int PREF_H = 650;
private int clickX;
private int clickY;
public DetectClicks() {
MyMouseListener mouseAdapter = new MyMouseListener(this);
addMouseListener(mouseAdapter);
addMouseMotionListener(mouseAdapter); // to allow dragging!
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
String str = String.format("[%d, %d]", clickX, clickY);
g.drawString(str, clickX, clickY);
}
public int getClickX() {
return clickX;
}
public void setClickX(int clickX) {
this.clickX = clickX;
}
public int getClickY() {
return clickY;
}
public void setClickY(int clickY) {
this.clickY = clickY;
}
private static void createAndShowGui() {
DetectClicks mainPanel = new DetectClicks();
JFrame frame = new JFrame("DetectClicks");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class MyMouseListener extends MouseAdapter {
private DetectClicks detectClicks;
public MyMouseListener(DetectClicks detectClicks) {
this.detectClicks = detectClicks;
}
#Override
public void mousePressed(MouseEvent evt) {
showPoint(evt);
}
#Override
public void mouseDragged(MouseEvent evt) {
showPoint(evt);
}
private void showPoint(MouseEvent evt) {
detectClicks.setClickX(evt.getX());
detectClicks.setClickY(evt.getY());
detectClicks.repaint();
}
}
Your event is getting consumed by the handler that prints the coordinates, you need to redispatch the event so that the button can see it. You can do it like this, inside the coordinate display event handler:
Component c = e.getComponent();
c.getParent().dispatchEvent( e );
Also, I'd be tempted to use the glass pane of the frame, and put a JLabel on it with the co-ordinates rather than messing with the paint method.
you don't have to use any of repaint(),invalidate() etc.
i highly recommend to use
SwingUtilities.invokeLater(new Runnable() {
public void run() {
//TODO udpdate UI compontents, layouts etc.
}
});
this guarantees that UI components update on real time. Because we don't know when the system update UI hierarchy so we can't force it. This allow system to determine by it's self.
I tried making a sprite animation in JAVA using Swing. The code below is an array of ImageIcon which I'm going to iterate through in order to show the several different images (only 2 for testing purposes).
But I don't know how to properly time each iteration. I mean, when I compile the code the label I'm working on, only displays the last image of the array (obviously), but I want it to display the first one for some ms and the other one after.
I made some research and saw some suggestions regarding Time class, but I don't really know how to implement it in these circunstances. I also tried to use sleep, which works fine in C++, but only came up with thread.sleep which doesn't work in this case.
The animation is supposed to simulate a playing card being turned around (for the Monopoly game).
Can anyone give me some input on the matter?
import javax.swing.ImageIcon;
import javax.swing.JLabel;
public class Sprite2 {
private ImageIcon[] sprites;
private ImageIcon a = new ImageIcon("C:/Users/Guilherme/Desktop/G/FEUP/2º Ano/2nd semester/Eclipse repos/Sprite/src/images/ball.jpg");
private ImageIcon b = new ImageIcon("C:/Users/Guilherme/Desktop/G/FEUP/2º Ano/2nd semester/Eclipse repos/Sprite/src/images/transferir.jpg");
public Sprite2() {
sprites = new ImageIcon[] {a, b};
}
public void render(JLabel lbl) {
for (int i = 0; i < sprites.length; i++) {
lbl.setIcon(sprites[i]);
//sleep(1000); - Looking for a similar Java function which is able to delay each iteration and make it look like a gif
}
}
You can use Swing timer, see How to Use Swing Timers for more details.
You should not use sleep() on Event Dispatch Thread as it will stop the thread from processing painting and other UI related events and the UI will become frozen. For more details see The Event Dispatch Thread tutorial.
I figured it out using timer.
For some reason, the first frame wouldn't show up in the first animation, hence sprites[0] and [1] are the same image.
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Sprite extends JPanel implements ActionListener{
private ImageIcon[] sprites = new ImageIcon[4];
private Timer time;
private int delay = 500, currentFrame = 0;
private ImageIcon a0 = new ImageIcon("C:/Users/Guilherme/Desktop/G/FEUP/2º Ano/2nd semester/Eclipse repos/Sprite/src/images/ball.jpg");
private ImageIcon a1 = new ImageIcon("C:/Users/Guilherme/Desktop/G/FEUP/2º Ano/2nd semester/Eclipse repos/Sprite/src/images/transferir.jpg");
private ImageIcon a2 = new ImageIcon("C:/Users/Guilherme/Desktop/G/FEUP/2º Ano/2nd semester/Eclipse repos/Sprite/src/images/smurf_sprite.png");
public Sprite() {
sprites[0] = a0;
sprites[1] = a0;
sprites[2] = a1;
sprites[3] = a2;
time = new Timer(delay, this);
time.start();
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
sprites[currentFrame].paintIcon(this, g, 0, 0);
if (currentFrame == sprites.length-1) {
time.stop();
}
else currentFrame++;
}
public void actionPerformed(ActionEvent e) {
repaint();
}
public static void main(String[] arg) {
JFrame f = new JFrame();
Sprite s = new Sprite();
f.add(s);
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setSize(500,400);
}
}
I'm learning Java here and trying to get to grips with classes and how best to catch mouse events etc. for my little game, so please be patient and give my some hints.
The main class of my project extends JFrame and upon construction adds to itself an object of a class which extends JPanel. This JPanel covers the whole window and it is this I am using to paint stuff to the screen. Then I have a class called Scene which extends nothing but which stores all the references to the current objects on the screen and is responsible for compiling them all and passing them back to the JPanel. I didn't want to put the full mouse event code in the JPanel because it would be so messy so I though I'd create another class for that called MEs and let each scene have one. My thinking was, this way each mes object can access the objects in each scene easily. So my code is looking like this:
class DPanel extends JPanel {
Scene scCurrent;
public DPanel() {
scCurrent = new Scene();
addMouseMotionListener(new MouseAdapter() {
public void mouseMoved(MouseEvent me) { scCurrent.mes.moved(me); }
});
...
}
...
but of course, inside scCurrent.mes.moved() I don't even know how to change the cursor. It doesn't recognise setCursor() in there. How can I change the cursor and access objects that are higher up the tree like I'd need to to switch scene? Or is there some other place I can tuck my mouse event handling code that will not bumph-out out my JPanel?
You are trying to separate out the control code from the view (GUI) code, and this is a good thing. A solution is to give the view code public methods that allow outside code to change its state, and give the control classes a reference to the view so that the controls (i.e., MouseListeners, MouseMotionListeners, ActionListeneres) can call these methods on a proper reference and change the view's states.
Edit 1
It may be easier just to show you an example:
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
public class ViewControl {
private static void createAndShowGui() {
View view = new View();
Control control = new Control(view);
view.addMouseAdapter(control);
JFrame frame = new JFrame("ViewControl");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(view);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
#SuppressWarnings("serial")
class View extends JPanel {
private static final int PREF_W = 400;
private static final int PREF_H = PREF_W;
private List<Point> points = new ArrayList<Point>();
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (points.size() > 1) {
for (int i = 0; i < points.size() - 1; i++) {
int x1 = points.get(i).x;
int y1 = points.get(i).y;
int x2 = points.get(i + 1).x;
int y2 = points.get(i + 1).y;
g.drawLine(x1, y1, x2, y2);
}
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
public void addMouseAdapter(MouseAdapter adapter) {
// addMouseListener(adapter);
addMouseMotionListener(adapter);
}
public void addPoint(Point p) {
points.add(p);
repaint();
}
}
class Control extends MouseAdapter {
private View view;
public Control(View view) {
this.view = view;
}
#Override
public void mouseDragged(MouseEvent e) {
view.addPoint(e.getPoint());
}
}