Accessing a variable of a thread from another thread in java

Question

I'm trying to access and modify a variable of a thread in another thread in java, and I really don't know how to do this.

ex :

Runnable r1 = new Runnable() {
    int value = 10;
    public void run() {
        // random stuff
    }
}
Runnable r2 = new Runnable() {
   public void run() {
        // of course the bellow line will not work
        r1.value--; // I want here to be able to decrement the variable "value" of r1
    }
}
Thread t1 = new Thread(r1);
Thread t2 = new Thread(r2);
t1.start();
t2.start();

thank you if you have any idea!

Is there any way to create a getter and setter for a thread in java?

EDIT : the answers were good, but I was not clear in my question, I will try asking a better question

Answer 1

You could make it sort of work but, I suggest you use an AtomicInteger which is shared between threads.

final AtomicInteger value = new AtomicInteger(10);
Runnable r1 = new Runnable() {
    public void run() {
        // random stuff using value
    }
}
Runnable r2 = new Runnable() {
   public void run() {
        value.decrementAndGet();
    }
}

You can use AtomicReference for references to objects.