Daniel Trebbien

// http://stackoverflow.com/questions/3605476/java-help-needed-sharing-an-object-between-two-threads-and-main-program
public class SO3605476
{
    public static void main(String[] args)
    {
        final int[] arr = new int[100];
        Thread t1 = new Thread() {
            public void run() {
                for (int i = 0; i < arr.length * 4000; i++) {
                    //synchronized (arr) {
                    arr[i % arr.length]--;
                    //}
                }
            }
        };
        Thread t2 = new Thread() {
            public void run() {
                for (int i = 0; i < arr.length * 4000; i++) {
                    //synchronized (arr) {
                    arr[i % arr.length]++;
                    //}
                }
            }
        };
        t1.start(); t2.start();
        try {
            t1.join(); t2.join(); // Wait until the threads finish
        }
        catch (InterruptedException e) { assert(false); }
        for (int i = 0; i < arr.length; i++) {
            System.out.printf("%d ", arr[i]);
        }
        System.out.println();
    }
}