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Thread: Synchronized a integer variable in Java

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    Default Synchronized a integer variable in Java

    Hi all

    I am trying to synchronized an integer variable in java.

    An example is as below:

    class Myclass{
    private static int numOfball

    public synchronized void getBall()
    {
    synchronized(numOfball)
    {

    }



    }

    The statement synchronized(numOfball) give me a problem.Can please advise how to synchronized numOfball??

    Thank you.


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    Default Re: Synchronized a integer variable in Java

    Quote Originally Posted by hellokitty25 View Post
    Hi all

    I am trying to synchronized an integer variable in java.
    This doesn't make sense. What do you mean by "synchronize" a variable. This cannot be done in Java, period. You can synchronize on an *object* not a variable, and it's often an object that is not used to hold a value, but rather simply to act as a lock.
    An example is as below:

    class Myclass{
    private static int numOfball

    public synchronized void getBall()
    {
    synchronized(numOfball)
    {

    }



    }

    The statement synchronized(numOfball) give me a problem.Can please advise how to synchronized numOfball??
    If you have a compiler error, post it here as well. But most important -- tell us what you're trying to achieve, not how you're trying to achieve it because your approach again is not only impossible, it doesn't make sense.

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    Default Re: Synchronized a integer variable in Java

    Hi

    What I am trying to achieved is that I will have 10 objects of Myclass which is a thread. The numOfball inside must not be overwrite.

    Regards

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    Default Re: Synchronized a integer variable in Java

    Quote Originally Posted by hellokitty25 View Post
    What I am trying to achieved is that I will have 10 objects of Myclass which is a thread. The numOfball inside must not be overwrite.
    If it's to be a constant, then make it a final variable. Or if I'm misunderstanding you, please clarify your problem some more.

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    Default Re: Synchronized a integer variable in Java

    Hi I am trying to create 10 objects of Myclass which extends Thread in the main class. The numOfball is passed to the Myclass objects and return to the main class.
    The numOfball must be synchronized to ensure that it is correct each time an object of Myclass is created

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    Default Re: Synchronized a integer variable in Java

    This looks like a homework assignment. Please post the actual assignment text. Let's see exactly what your requirements are.

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    Default Re: Synchronized a integer variable in Java

    Hi

    I almost got the output. Just that as this is a thread, the numOfballs must be synchronized. Otherwise the numOfball will not be correct.

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    Default Re: Synchronized a integer variable in Java

    Quote Originally Posted by hellokitty25 View Post
    Hi

    I almost got the output. Just that as this is a thread, the numOfballs must be synchronized. Otherwise the numOfball will not be correct.
    Again, a variable cannot be synchronized. What probably must be synchronized is the method that sets this variable. Make this variable volatile, and then you will need to use a shared Object that it can synchronize perhaps a static public Object held by a variable called "lock". Whatever you do, do not synchronize on an object of the class that you make 10 instances of.

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