Develop Reference

Java StopWatch in ChessGame

I have two threads in my ChessGame and I want to implement time control:
Turn of first player: second_thread.stop(), first_thread.run();
counterOfSteps++;
Turn of second player: first_thread.stop(), second_thread.run();
counterOfSteps++;
I have founded many information about Timer but I need Threads.Second thread the same.
There is my code of first thread and it doesn't work because time isn't stopped (System.currentTimeMillis)
first = new Thread() {
#Override
public void run() {
final long time = System.currentTimeMillis();
final long duration = 10800000; //3 hours
while (true) {
try {
Thread.sleep(100);
if (counterOfSteps % 2 == 0) {
System.out.println("Time" + ((duration - (System.currentTimeMillis() - time)) / 1000) % 60);
}
} catch (InterruptedException ex) {
LOG.log(Level.SEVERE, "Unexpected interrupt", ex);
}
}
}
};
How to solve this problem?
Update:
I don't use .stop(). I wrote is for example how to realize.

I have founded many information about Timer but I need Threads.
No. If all you are trying to do is implement a chess clock, then you don't need threads for that. A Timer task that wakes up every second (or every 1/10 second) can;
look at whose turn it is (e.g., counterOfSteps % 2),
compute how much time that player has used, and
Update the appropriate text box in the GUI.
To compute how much time, it'll need to know three things;
What time it is now (e.g., System.currentTimeMillis()),
What time it was when the current turn started, and
How much time the player already had on the clock when the current turn started.
There is no way to pause the system clock (i.e., System.currentTimeMillis()), but that's not a problem. If you sample the clock at the start of each turn, then you can compute the duration of the current turn as System.currentTimeMillis() minus the start time.

I used this example for my quiz, i have 10sec do answer on question this timer decrease int t every 1sec, and set how many times left in some JLabel. You can make 2 object of Timer, first object for first player and second object for second player. You can stop timer when someone finish the move and start second timer...
int t=10
lb2=new JLabel(t);
tim=new Timer(1000,new ActionListener(){
#Override
public void actionPerformed(ActionEvent e){
if(t>0){
t--;
lb2.setText(String.valueOf(t));
}else{
tim.stop();
JOptionPane.showMessageDialog(null, "Time is up");
}
}
});
}

Keeping timer events equally spaced

I'm attempting to get an animation working in a game I'm developing. The animation works by setting a button size to very small, then gradually growing it to its normal size again. I have it working, except I'm having timing issues.
Sometimes the button will grow almost instantly, sometimes it goes VERY slow. I'm looking for something inbetween, and I need it to ALWAYS grow at that size, not some times fast sometimes slow.
I've looked into it and I found this pseudocode:
distance_for_dt = speed * delta_time
new_position = old_position + distance_for_dt
Unfortunately I don't understand what's being said, and I don't know how to apply this to my code. Can anyone help with that or explain what's being said in the above pseudocode?
Here's my timer code, timer is already defined above as a Timer, and z[] is just a pair of coordinates:
timer = new Timer(18, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
Dimension dim = button[z[0]][z[1]].getSize();
if (dim.getHeight() < 79.9) {
button[z[0]][z[1]].setSize((int) (dim.getWidth() + 6), (int) (dim.getHeight() + 6));
} else {
button[z[0]][z[1]].setSize(80, 80);
timer.stop();
}
}
});
timer.start();

Depending on how many updates you're calling on your Swing application, it may be getting "backed up" and slowing down. For instance, if you wanted to accomplish the animation without a Timer, you could just do something like this:
// example method to do animation
public void animateButton(final int wait){
Thread thread = new Thread(){
public void run(){
// some loop structure to define how long to run animation
Dimension dim = button[z[0]][z[1]].getSize();
while (dim.getHeight() < 79.9){
SwingUtilities.invokeLater(new Runnable(){
//update Swing components here
});
try{ Thread.Sleep(wait); }
catch(Exception e){}
}
}
}
}
thread.start();
}
I think this may be similar to how a Timer updates the GUI, as Timers run on a separate thread. I would look into whether or not you need to use invokeLater(new Runnable) inside a timer to properly schedule the task. I had to do this to allow a project I was working on to keep responsive during long tasks. If you really needed to ensure the speed and maybe DROP updates to adjust for system lag, then you'll need to be calculating how complete the animation is vs how much time has passed, using a method call such as System.currentTimeMillis() or System.nanoTime(). Then, adjust accordingly for each step of the animation.

JLabel graphic changes at wrong time

I have a slot machine program with some graphics, and the graphic is supposed to change when you pull the lever and for some reason it changes the graphic after it goes through all of the other code first. Have a look:
Declare images:
static ImageIcon jImage = new ImageIcon("C:\\Users\\Harry\\Desktop\\jackpotLeverNotPulled.png");
static ImageIcon jackpot1 = new ImageIcon("C:\\Users\\Harry\\Desktop\\jackpotimage1.png");
static ImageIcon jackpotPulled = new ImageIcon("C:\\Users\\Harry\\Desktop\\jackpotLeverPulled.png");
Now I add to panel:
static JLabel jlb = new JLabel(jImage);
Now I want the image to change when a certain area is clicked on my panel but the main jackpot code runs first and then the image changes:
public void mousePressed(MouseEvent e) {
// Returns the X coordinate of where the mouse was click on the panel
System.out.println("X Coordinate: " + e.getX() );
// Returns the Y coordinate of where the mouse was click on the panel
System.out.println("Y Coordinate: " + e.getY() );
System.out.println();
Scanner ansr = new Scanner(System.in);
String yesno;
int random = (int)(Math.random() * 21 );
int percentCheck = (int)(Math.random() * 10 );
if (e.getX ()>975 && e.getX ()<1159 && e.getY ()>82 && e.getY ()<218){
jlb.setIcon(jackpotPulled);
if (cashMoneyz<1) {
System.out.println("Insufficient funds");
image1.setIcon(jackpot1);
} else {
System.out.println("One dollar has been removed from you slot machine balance");
cashMoneyz--;
try {
System.out.println("Spinning...");
Thread.sleep(1000);
System.out.println("Spinning...");
Thread.sleep(1000);
System.out.println("SPINNINGGGGG...OMG SOOO INTENSE");
Thread.sleep(1000);
} catch (InterruptedException ie)
{
}
}
System.out.println("You have this much money (in dollars) left in your slot machine balance: " + cashMoneyz);
System.out.println("");
System.out.println("----------------------------------------------------------------------------------");
}
It does the if statements and try catches and only changes the graphic to jackpotPulled at the end of everything.
Thanks in advance :)

There are basically 2 problems in your code:
1)
A call to label.setImage() won't update immediately, as this is true for everything in AWT and Swing. Any time a repaint request is fired, it is simply added to a repaint queue, that will wait patiently for all other tasks done in the EDT (Event Dispatching Thread) to finish. But since you do other things in the mousePressed(), they will run first. A simple solution for this would be to do the computing in mouseReleased(). But a bigger problem exists.
2)
What you are currently doing is "starving" the EDT - a bad programming practice - as all screen related invocations must be executed immediately. Sleeping the EDT won't allow any repaints to take place while running. This is true for any long running tasks as well.
Its solution is to run the non-painting calls in a different thread:
private volatile boolean isComputing = false;
public void mousePressed(MouseEvent evt) {
if(isComputing)
return;
isComputing = true;
// .
// .
// .
// change icon here, or any
// other swing related change.
// .
// .
// run game
new Thread(){
public void run(){
// all non-swing computations
SwingUtilities.invokeLater(new Runnable() {
public void run() {
// change back icons,
// and some other swing updates
}
}
isComputing = false;
}
}.start();
}

An event handler (mousePressed) souldn't take a long time to complete, there should be no sleeps in it. As long as it runs (or sleeps), nothing else can happen. The runtime is waiting for the handler to return and displays the image after that. I would move most of the code to a function called by a timer, and use a state variable to keep track of how intensely the wheels are spinning.

LibGDX stop time counter on pause

In LibGdx, is there a way to pause the delta time when user pause the screen/left apps temporary (such an incoming call)? Take for example, when displaying message is going to take 10 secs for user to read the message, normally, I would get the message displayed start time, do the calculation in render() to get the elapsed time (currentTime - MessageStartedTime), if elapsed time > 10secs, then close message, everything works correctly, right. Imaging this scenario, user is reading the message (let assume elapse time is 2 secs), an incoming call that took 20 secs, when the process is brought back to my apps, the elapsed time > 10 secs, and therefore the message will be removed even though the message is only displayed for 2 secs.
so, my question is, is there a master time counter that I can implement in my application for this kind of purposes? and what is the best way to implement it?

I have two game states, they are:
GAME_RUNNING
GAME_PAUSED
When pause() is called I set the state to GAME_PAUSED and when resume() is called I set the state to GAME_RUNNING.
And then when I run update() on my game I check this state and if it's paused I set delta to 0.
float deltaTime = game.state == GAME_PAUSED ? 0 : Gdx.graphics.getDeltaTime();
This means when all my game objects update, their changes are multipled by 0 and nothing changes. We can also add a condition and only update when deltaTime > 0.
If you have a timer, you'll be updating this timer somehow like:
public void update(World world, float delta) {
frameTimer += delta;
if( frameTimer >= rate / 1000) {
fireAtEnemy(world);
frameTimer = 0;
}
}
Because delta is now 0 the timer will not increase and not increase until the game state it back to GAME_RUNNING after resume().
Additionally, you can add an extra state called something like GAME_RUNNING_FAST and when this state is set you can multiply the deltaTime by 2 for example. If you have all your updates relative to the deltaTime then your entire game will run at double speed. If that's something you'd desire.

private long pauseTime = 0;
private long pauseDelay = 0;
#Override
public void pause() {
pauseTime = System.nanoTime();
}
#Override
public void resume() {
pauseDelay = System.nanoTime() - pauseTime;
pauseTime = 0;
}
And in your render method you just do long displayTime = delta - pauseDelay; pauseDelay = 0;

Displaying JLabel movement

I am attempting to create a simple animation in which a series of bubble rotate around a centre point. I have one version of animation where the bubbles spread from the centrepoint before they begin to rotate, which works fine, but as soon as I click one of the images (which sparks the animation) the screen freezes for a moment and then the bubbles appear in their end position, rather than showing each step they made.
What I have so far is:
while(bubble[1].getDegree() != 270)
{
long time = System.currentTimeMillis();
//the below if statement contains the function calls for
//the rotating bubble animations.
next();
draw();
// delay for each frame - time it took for one frame
time = (1000 / fps) - (System.currentTimeMillis() - time);
if (time > 0)
{
try
{
Thread.sleep(time);
}
catch(Exception e){}
}
}
public void draw()
{
for(int i = 1; i < bubble.length; i++)
{
iconLabel[i].setLocation(bubble[i].getX(), bubble[i].getY());
textLabel[i].setLocation((bubble[i].getX()+10),(bubble[i].getY()+10));
}
}
For clarity, the method "next()" merely changes the position of the bubble to the appropriate place, I know this to be functioning as I have had the animation work before but once I implemented the animation to JLabels it stopped working.
Any help would be appreciated.

The drawing is frozen because you block the event dispatch thread. Drawing is done in the same thread as the while loop, and since the loop prevents anything else happening while it's running, swing can get to drawing only after the loop is finished, so only the last position is drawn.
Use a swing Timer instead:
timer = new Timer(delay, new ActionListener() {
public void actionPerformed(ActionEvent e) {
// whatever you need for the animation
updatePositions();
repaint();
}
});
timer.start();
And then call timer.stop() when all the frames you need have been processed.