How to know if the java program is already running?

Question

I have a simple java program, and I need some way to know if this program is already running. I need it because when I execute this program and during this execution I execute it again, two java programs are running in the Operating System. Is there any java method that tells if the current program is already running?

Answer 1

Hey, stevejluke and nicklap, do you know about Threads? I NEED SOME HELP, URGENTLY!!! I�ve posted the same problem two times in this forum, but nobody gave me the solution. It seems to be very simple, and I�m very angry because I am wasting a long time because this ridiculous problem. Read the text below please. If you know some suggestion or tip, tell me!
Sorry for posting this topic again. But I need some suggestion urgently. I put the last post below.
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I�ve been trying to test my application in Eclipse, and I am using threads. But when I debug it, sometimes the behavior is not what I am expecting. Sometimes when I stop at some breakpoint for a long time, the debug stops to execute. Curiously the application runs perfectly in run mode.
Has anyone had this problem?
Thanks.
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(m.winter)
Debugging threads works perfectly in eclipse. However be aware: If you just set a breakpoint by doubleclicking left to the source line, then its policy ist to stop the trhread, not the VM. That means, once you reach the breakpoint, only the thread reaching that line is stopped. All other threads continue running. If a second thread later also hits that line, it is also stopped. This makes it sometimes difficult to find out, where you are, as two or more threads may be suspended. You can see the status of the threads and switch between them in the treah view, typically in the upper half of the screen.
You can change the behaviour of a breakpoint to "suspend VM" by left-clicking on the breakpoint and choosing breakpoint properties.
I assume in your case, that other threads are continuing to run. They may e.g. produce data, which is supposed to be worked on by the suspended thread. If you stay a long time at the breakpoint, finally you might run out of memory or something else happens, which does not occur in run mode.
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(Peter-Lawrey)
If you have anything in your code which is time depend it can run fine, except when you debug it.
e.g. if one thread times out because you have stopped another thread.
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Thanx, but I didn�t understand yet.
Sorry if I commit any English language error, I�m learning English.
Please try to debug the code below:
public class Main {
    public static void main(String[] args) {
        Shared objShared = new Shared();
        Thread thread1 = new Thread(new Thread1(objShared));
        Thread thread2 = new Thread(new Thread2(objShared));
        thread1.start(); //put breakpoint here
        thread2.start();
class Thread1 implements Runnable {
    private Shared objShared;
    Thread1(Shared shared) {
        objShared = shared;
    public void run() {
        try {
            objShared.doSomething1();          
        } catch(InterruptedException e) {
            e.printStackTrace();
class Thread2 implements Runnable {
    private Shared objShared;
    Thread2(Shared shared) {
        objShared = shared;
    public void run() {
        try {
            objShared.doSomething2();          
        } catch(InterruptedException e) {
            e.printStackTrace();
class Shared {
    private boolean x = false;
    synchronized void doSomething1()
        throws InterruptedException {
        while (x) //put breakpoint here
            wait();
        System.out.println("Doing something 1");
        x = true;
        notifyAll();
    synchronized void doSomething2()
        throws InterruptedException {
        while (!x)
            wait();
        System.out.println("Doing something 2");
        x = false;
        notifyAll();
}"If you stay a long time at the breakpoint, finally you might run out of memory or something else happens" - I don�t wait a very long time. Just few seconds in the "while" breakpoint is enough to debug stops the execution.
"You can change the behaviour of a breakpoint to "suspend VM" - I did it, but in properties I didn�t find any thing to configure in order to debug perfectly.
In debug mode, when I press F6 button rapidly, this program is executed perfectly. The problem occurs only if the debug is stopped for few seconds in breakpoint. Try it, I�m really interested in the cause of this behaviour.
Thanks a lot!
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I don�t know why does this behaviour occur! If anyone has the solution for my problem, please tell me!
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