Question

I would like to write a utility that will provide me with a relatively unique ID in Java. Something pretty simple, like x bits from timestamp + y bits from random number.

So, how would I implement the following method:

long getUniqueID() {     long timestamp = System.currentTimeMillis();     long random = some random long      ...      return id; } 

BONUS

Any suggestions for other easily obtainable information I could use to form my ID?

note: I am aware of GUIDs and I know Java has a UUID class, but I don’t want something that is 128 bits long.

Answer 1

Just clip the bits you don’t need:

return java.util.UUID.randomUUID().getLeastSignificantBits();