I'm creating a java 2D platformer game, and I'm having a little trouble getting an animation to go through when the player dies. When the player dies, all enemies are removed and an explosion animation is played where they used to be. At the same time, the player begins to blink. I want that to go on for about two seconds, and then have my setState() method switch to the "PlayerDeadState", which is basically the retry or return to main menu option screen. I've used Thread.sleep(), but it doesn't work, and I've heard it's bad for GUI threads.
Here is my code:
public void update() {
// check if player is dead
if(player.dead == true) {
player.flinching = true;
for(int i = 0; i < enemies.size(); i++) {
Enemy e = enemies.get(i);
e.update();
e.hit(200);
if(e.isDead()) {
enemies.remove(i);
i--;
eExplosions.add(
new Explosion(e.getx(), e.gety()));
}
}
gsm.setState(3);
}
}
The animations go through if I comment out my setState() method. The problem with this is the fact that I can't have both currently. Animations, or loading a necessary GameState. I want both. :P
Any suggestions?
You could make use of swing timers:
ActionListener listener = new ActionListener(){
public void actionPerformed(ActionEvent event){
gsm.setState(3);
}
};
Timer timer = new Timer(2000, listener);
timer.setRepeats(false);
timer.start();
Related
So, I am creating the snake game using JavaFX and I cannot seem to make the game pause properly, i.e. it pauses occasionally and other times, the game just ignores the pause. So, basically I have a Main class where I initialize all the GUI components, and it also acts as the controller for the javafx Application.
I have a Button named gameControl which starts/pauses the game, a variable Boolean pause which keeps track of the game states (new/paused/running), and the methods startGame, pauseGame.
The gameControl button's EventHandler is as follows:
gameControl.setOnClicked(event->{
if(paused == null) startGame(); //new game
else if(paused) continueGame(); //for paused game
else pauseGame(); //for running game
});
The startGame function looks something like this:
void startGame(){
paused = false;
Snake snake = new Snake(); //the snake sprite
//following gameLoop controls the animation of the snake
gameLoop = new AnimationTimer(){
#Override
public void handle(long now){
drawSnake(); //draws the snake on the game
snake.move(); //move snake ahead
//following code is for slowing down the gameLoop renders to make it easier to play
Task<Void> sleeper = new Task<>(){
#Override
protected Void call() throws Exception {
gameLoop.stop();
Thread.sleep(30);
gameLoop.start();
return null;
}
};
new Thread(sleeper).start();
//force garbage collection or else throws a bunch of exceptions after a while of running.
//not sure of the cause...
System.gc();
}
};
gameLoop.start();
}
AnimationTimer gameLoop are variables of the class to allow calling from other functions.
And the pauseGame function:
void pauseGame() {
paused = true;
gameLoop.stop();
}
So, as I have said before the game doesn't pause everytime I hit the gameControl button, and I suspect it is due to the Thread.sleep(30); line inside the Task of the gameLoop. That being said, I am still not fully sure and have no idea how to fix this. Any help would be appreciated.
What type is 'paused' ? You check it for null, but then treat it as a boolean.. I can't understand why it would be a big 'B' Boolean object wrapper instead of the primitive boolean type.
This:
//following code is for slowing down the gameLoop renders to make it easier to play
Task<Void> sleeper = new Task<>(){
#Override
protected Void call() throws Exception {
gameLoop.stop();
Thread.sleep(30);
gameLoop.start();
return null;
}
};
Is an absolutely horrible way to throttle the speed. Let your game loop run, check the time on each loop to see if enough time has elapsed that you should update things. Your animation timer will drive the game. You don't want to pause the main platform thread, you don't want to pause any worker threads that are handling tasks. If you are scheduling tasks have them scheduled to run at the intervals that you want - don't throttle the thread in the call() method.
What you really want is something like this:
//following gameLoop controls the animation of the snake
gameLoop = new AnimationTimer(){
#Override
public void handle(long now){
if ((now - lastTime) > updateIterval) {
drawSnake(); //draws the snake on the game
snake.move(); //move snake ahead
lastTime = now;
}
You could even make that a loop to "catch up" in case the Animation timer fell behind for some reason:
while ((now - lastTime) > updateIterval) {
drawSnake(); //draws the snake on the game
snake.move(); //move snake ahead
lastTime += updateIterval;
}
Your intuition that Thread.sleep(30); may be causing an issue is on the right track. A user may click the button calling pauseGame, setting paused to true, and telling the gameloop to stop. If the new sleeper thread is started and sleeping at that moment it will call start() on the gameloop when it wakes up.
One option may be to simply check the value of paused in the sleeper task to determine if it should start the gameloop.
Task<Void> sleeper = new Task<>(){
#Override
protected Void call() throws Exception {
gameLoop.stop();
Thread.sleep(30);
if (!paused) {
gameLoop.start();
}
return null;
}
};
Given that the paused value is being set and read from multiple threads, I would recommend adding a mechanism to ensure you don't get non-deterministic behavior. Swapping the Boolean to an AtomicBoolean is a straight forward option for ensuring consistency.
I'm new to JAVA and trying to learn some concurrency concepts.
I have a simple GUI class that pops-up a window with 1 button which I want to use for pause/continue.
Also, I have a class that extends TimerTask, it looks like below and start with the GUI:
public class process extends TimerTask {
public void run() {
while(true) { /*some repetitive macro commands.. */ }
}
}
Real question is, how can I pause the task onClick of the button and also continue onClick of the button if already paused?
I have taken a step to use a boolean to flag the button as it changes from pause to continue on each click.
But then I had to type a lot of while(button); for busy waiting inside the while()...
Do you think I can make like Thread.sleep() or something but from outside the task thread?
OLD ANSWER
Basically, there is no support for pause and resume on TimerTask, you can only cancel, check here
perhaps you might want to read about threading as that's the alternative I know of that has an interrupt and start features and then you can keep track of the progress of what you're doing to resume where it stopped.
So, I will suggest you go through this link, because you need to understand threading not just copy a code to use, there is a sample code there that will definitely solve your problem also.
Note that running an endless while loop will basically cause your program not to respond, unless the system crashes. At a certain point, the data becomes an overload and the program will overflow. This means it will fail.
.
NEW ANSWER
So, response to the new question, I was able to run a tiny little program to demonstrate how you can achieve something that looks like multithreading when working with SWING.
To rephrase your question: You want to run an indefinite task like let say we're playing a song, and then onclick of a button to pause the song, on click again should continue the song?, if so, I think below tiny program might work for you.
public class Test{
static JLabel label;
static int i = 0;
static JButton action;
static boolean x = false; //setting our x to false initialy
public static void main(String[] args) {
JFrame f=new JFrame();//creating instance of JFrame
label = new JLabel("0 Sec"); //initialized with a text
label.setBounds(130,200,100, 40);//x axis, y axis, width, height
action=new JButton("Play");//initialized with a text
action.setBounds(130,100,100, 40);//x axis, y axis, width, height
f.add(action);//adding button in JFrame
f.add(label);
action.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e){
if(x){
x = false; //Update x here
action.setText("Play");
action.revalidate();
}else{
x = true; //Update x here also
action.setText("Pause");
action.revalidate();
if(x){ //Using x here to determind whether we should start our child thread or not.
(new Thread(new Child())).start();
}
}
}
});
f.setSize(500, 700);//500 width and 700 height
f.setLayout(null);//using no layout managers
f.setVisible(true);//making the frame visible
}
}
class Child implements Runnable{
#Override
public void run() {
while (x) {
//You can put your long task here.
i++;
label.setText(i+" Secs");
label.revalidate();
try {
sleep(1000); //Sleeping time for our baby thread ..lol
} catch (InterruptedException ex) {
Logger.getLogger("No Foo");
}
}
}
}
I'm having trouble with this code I am using to create a roulette wheel. The goal is to spin the wheel when I click the "SPIN!" button. I have done this by creating a for loop that should change the status of the wheel from true to false, which changes the orientation. This, when done fast enough, should create the illusion of movement.
THE PROBLEM I AM HAVING: is that my wheel is only repainting after the whole for loop is done, despite my placement of the repaint(). So, it only spins one tick.
Here is some sample code of my ActionListener:
public class spinListener implements ActionListener
{
RouletteWheel wheel;
int countEnd = (int)(Math.random()+25*2);
public spinListener(RouletteWheel w)
{
wheel = w;
}
public void actionPerformed(ActionEvent e)
{
for (int i = 0; i <countEnd; i++)
{
try
{
Thread.sleep(100);
if (wheel.getStatus() == true)
{
wheel.setStatus(false);
repaint();
}
if (wheel.getStatus() == false)
{
wheel.setStatus(true);
repaint();
}
}
catch (InterruptedException ex)
{
Logger.getLogger(WheelBuilder.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
}
UPDATE: I figured out the problem. Here are the changes I made for anyone having a similar problem.
public class spinListener implements ActionListener
{
Timer tm = new Timer(100, this);
int count = 0;
public void actionPerformed(ActionEvent e)
{
tm.start();
changeWheel();
}
public void changeWheel()
{
int countEnd = (int)(Math.random()+20*2);
if (count < countEnd)
{
wheel.setStatus(!wheel.getStatus());
repaint();
count++;
}
}
}
Swing is a single threaded environment, anything that blocks the Event Dispatching Thread, will prevent it from been able to process new events, including, paint events.
The use of Thread.sleep within the actionPerformed method is blocking the EDT, preventing it from processing new events, including paint events, until the actionPerformed method is exited.
You should use a javax.swing.Timer instead.
Take a look at Concurrency in Swing and How to Use Swing Timers for more details
I need to make a GUI where a worker enters a station (a spot on the panel) and stays there for a set amount of seconds, shown in a countdown about the workers head (so, once the workers moves to the spot, the station's label shows 3s -> 2s -> 1s and then the worker leaves, and the label reverts back to "OPEN"). I'm having trouble with making this happen, as I'm not too good with the Timer(s?) that Java has. I tried with something like this:
Timer timer = new Timer(1000, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e)
{
//change label text/color, decrement countdown
panel.repaint();
Thread.sleep(1000);
}
});
But I can't reach the number of seconds to count down from from inside the timer, and I'm not sure how to pass that value to the timer. If someone can help me out, I'd really appreciate it.
Get rid of the Thread.sleep(). That's what the 1000 in Timer(1000, new ActionListener() does. It sets an interval for each timer event. Every time a timer event is fired, the actionPerformed is called. So you need to determine what needs to happen every "tick", and put that code in the actionPerformed. Maybe something like
Timer timer = new Timer(1000, new ActionListener() {
private int count = 5;
#Override
public void actionPerformed(ActionEvent e) {
if (count <= 0) {
label.setText("OPEN");
((Timer)e.getSource()).stop();
count = 5;
} else {
label.setText(Integer.toString(count);
count--;
}
}
});
You need to decide when to call timer.start().
For general information, see How to Use Swing Timers
Problem #1: You are calling Thread.sleep() from within the Swing GUI thread. That causes the thread to stop taking input and freeze. Delete that line. It does you no good! While you are at it, delete the repaint call as well.
Now that that's said and done, instead of creating an anonymous instance of ActionListener, you can create an actual class that implements ActionListener and provides a constructor. That constructor can have as an argument the number of seconds you want to start counting down. You can declare that class inside the method you are using, or you can declare it inside the class.
Here's a skeletal example:
public class OuterClass {
JLabel secondsLabel = ...;
Timer myTimer;
private void setupTimer(int numSecondsToCountDown) {
secondsLabel.setText(Integer.toString(numSecondsToCountDown));
myTimer = new Timer(1000, new CountdownListener(numSecondsToCountDown));
myTimer.start();
}
// ...
class CountdownListener implements ActionListener {
private int secondsCount;
public CountdownListener(int startingSeconds) { secondsCount = startingSeconds; }
public void actionPerformed(ActionEvent evt) {
secondsLabel.setText(Integer.toString(secondsCount);
secondsCount--;
if (secondsCount <= 0) { // stop the countdown
myTimer.stop();
}
}
}
}
I already have a post related to the multithreading issue but I have some new questions+code. I have a multiball game project and it requires me to parse an XML file to obtain information about the ball(like size, speed, initial position etc). Now, I wanted to create a different thread to parse the XML file, but I cannot figure out a way to do it. Here is my code:
main() starts here:
public class BounceBallApp extends JFrame{
public BounceBallApp()
{
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("BounceBallApp");
setSize(300,300);
setVisible(true);
add(new BallWorld());
validate();
}
public static void main(String[] args)
{
/*Create main GUI in the Event Dispatch Thread*/
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new BounceBallApp(); //main frame
}
});
}
}
Within the constructor for BallWorld(), I have an inner class BallContainer(), which contains a Start button:
jbtStart.addActionListener(new ActionListener()
{public void actionPerformed(ActionEvent e)
{
//Populate the ballList arraylist
if(filePathField.getText().equals(" "))
{
JOptionPane.showMessageDialog(null, "Please input the XML file","Information", JOptionPane.INFORMATION_MESSAGE);
}
else
{
XMLFilePath = filePathField.getText();
ballList = new BallList(XMLFilePath);//I want to put this in a thread
JOptionPane.showMessageDialog(null,"Game started!","Bouncing Balls",JOptionPane.INFORMATION_MESSAGE);
for(Ball ball:ballList.ballsArrayList)
{
timer.setDelay(1000/ball.getSpeed()); //change the delay of the timer to the ball's speed
timer.start(); //start the timer
bTimer = true; //timer is now on
}
}
}
});
}
Now the problem is that if I put the parsing process in another thread, then I have to wait for the ballsArrayList to fill before I can continue with the application. I was thinking of using invokeAndWait() but I read that that method cannot be called from the Event Dispatch Thread. So, How can I achieve this? Or is it even worthwhile?
Also, I wanted to move the calculation for moving the ball (calculating the x,y coords) to a thread, but again, I don't know how to implement it.
for(Ball ball:ballList.ballsArrayList)
{
ball.draw(g);
ball.move(ballContainerWidth,ballContainerHeight,buttonPanel.getHeight());
}
public void move(int ballContainerWidth,int ballContainerHeight,int buttonPanelHeight)
{
if((this.getX()+this.getsize()+this.getDx()) > ballContainerWidth)
{
this.setDx(-Math.abs(this.getDx()));
}
//the height/depth to which the balls can bounce is the (main ball container height) minus (button panel height)
if((this.getY()+this.getsize()+this.getDy()) > ballContainerHeight-buttonPanelHeight)
{
this.setDy(-Math.abs(this.getDy()));
}
if((this.getX()-this.getsize()) < 0 )
{
this.setDx(Math.abs(this.getDx()));
}
if((this.getY()-this.getsize()) < 0 )
{
this.setDy(Math.abs(this.getDy()));
}
int newX = (int)Math.round((this.getX()+this.getDx()));
int newY = (int)Math.round((this.getY()+this.getDy()));
this.setX(newX);
this.setY(newY);
}
Sorry for the long post, but multithreading is all new to me. I am a bit confused about it.
Initial loading of the files
I personally would opt for one of the following approaches
Increase the start-up time of your program by parsing all the files during start-up. For a few XML files this overhead might be very small. If it takes too long, you can consider showing a splash screen
Load the XML files when the start button is pressed, but show a progress bar until the loading is done. Start the game afterwards. A SwingWorker can help you with this. Examples can be found in the Swing documentation or here on SO.
Updating of the ball position
If the calculation is as easy as what is shown here, I would simply use a javax.swing.Timer to update the position on regular time intervals, and do the calculation on the Event Dispatch Thread.
If you want to do the calculation on a background thread just for the exercise, I would still opt for a calculation of the position on a background thread. The calculation should be using local variables which are only know to that background thread. Once the new position is calculated, update the position of the ball on the Event Dispatch Thread using SwingUtilities#invokeLater. This allows you to access the position during the paint operation without having to worry about threading issues. Probably easier then messing around with locks.