如何在不冻结的情况下以相同的方法运行2个线程？

Question

I'm creating a game, and I require 2 threads being run in the same method, however, only 1 of them is moving. The first thread counts in seconds, and the other one handles ingame power (no, this is not Five Nights at Freddy's). My game already has quite alot of files, and I do not think showing them all is a good idea, I'll only show the method that starts both threads.

@Override
public void mouseClicked(MouseEvent e) {
    System.out.println(e.getX() + ", " + e.getY());
        if (e.getX() > game.panel.startbtnx
            && e.getX() < game.panel.startbtnx + 96
            && e.getY() > game.panel.getHeight() / 2
            && e.getY() < game.panel.getHeight() / 2 + 36) {
        if (game.state == State.MENU) {
            game.state = State.GAME;
            Ingame.alerts.add(new Alert("-9999 Points!"));
            Ingame.powerhandler.start();
            Ingame.secondcounter.start();
        }
    }
}

As you can see, my "powerhandler" thread works perfectly, however the "secondcounter" thread does not work, and if I switch they're places, then only secondcounter works, and not powerhandler. What should I do?

EDIT: These are my thread codes, I have more threads, but right now I'm only using these 2:

class SecondCounterHandler implements Runnable {

    public static int seconds = 0;
    public Thread thread;

    public void start() {
        thread = new Thread(this);
        thread.start();
    }

    @Override
    public void run() {
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e1) {
            e1.printStackTrace();
        }
        while (true) {
            try {
                Thread.sleep(1000);
                seconds++;
            } catch(InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

}

and

class CityPowerHandler implements Runnable {

    public int power = 100;
    public Thread thread;

    public void start() {
        thread = new Thread(this);
        thread.start();
    }

    @Override
    public void run() {
        Thread.yield();
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e1) {
            e1.printStackTrace();
        }
        while (true) {
            if (power > 0) {
                power--;
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } else {
                Game.g.state = State.LOSE;
            }
        }
    }
}

Answer 1

As you can see, my "powerhandler" thread works perfectly

As we can see? See from what? You have not shown us any output or described any behavior.

however the "secondcounter" thread does not work,

What do you mean it "does not work"? What would it do if it worked? What does it do instead?

and if I switch [their] places, then only secondcounter works, and not powerhandler.

What does that mean, "switch their places?" Threads do not have "places." Are you talking about the order in which you start them?

---

One thing that might be a problem is here:

public void run() {
    ...
    while (true) {
        if (power > 0) {
            power--;
            ...
        } else {
            Game.g.state = State.LOSE;
        }
    }
}

As soon as power reaches zero (approx 10 seconds after the thread is started), this thread is going to loop forever, using 100% CPU, to continually set Game.g.state = State.LOSE .

That might not be what you intended.

Answer 2

Using threads for things like this is not a good idea. Use a swing Timer instead, it will make a lot of things easier and safer.

Thread safety

A swing timer runs on the Event Dispatch Thread , that means you don't have to synchronize things for thread safety.
If you use threads and, for example, modify the power member variable from another thread, things could get weird:

if (power > 0) {
    power--;
    ....

This thread could be interrupted between if and power-- , and if another thread sets power to zero, power may be -1 in the end.
Such errors can be very difficult to find later, because the will only occur rarely. Typically, when you are not debugging, but showing your program to someone else.

InterruptedException

no need to deal with InterruptedException s with timers.

Performance

should be better without creating many threads.

Simplicity

Your code could be more readable with timers, you can handle timer events just like the other events.

Answer 3

At the start of the method run, why not try to add Thread.yield(); ?

See: http://www.tutorialspoint.com/java/lang/thread_yield.htm

In that case, the Thread will let other 'waiting' Thread to execute before continuing.

Edit: Try to add the Thread.yield(); inside the while(true) loop

Answer 4

I assumed you using this value somehow on gui (from EDT thread) and noticed it is not changing. If that is the issue, you have visibility problem in your code, accessing variable across different thread without proper publishing/synchronization.

public static int seconds = 0;

Please use AtomicInteger from java.util.concurrent.atomic package.

public static AtomicInteger seconds = new AtomicInteger(0);

and use

seconds.incrementAndGet();

instead of

seconds++;