Since the granulaty of a PC can be as high as 55ms (down to 10ms), you can't use the System time
to generate a unique ID because of the risk of getting duplicated IDs.
This can be solved by using the following technique to make sure that the number returned
is unique (in a single JVM).
public class UniqueID {
static long current= System.currentTimeMillis();
static public synchronized long get(){
return current++;
}
}
