public static void increment() {
synchronized( locker ) {
x = x + 1;

}

}
"

should be replaced with

public static int x = 1;
public static synchronized void increment() {
x = x + 1;
}

as it is otherwise not guarranted to work as expected when multiple threads are involved (lookup articles on javaworld.com and postings in comp.lang.java.programmer if you don't believe me...