Java: Unique 10 digit ID

Question

I need to generate a unique 10 digit ID in Java. These are the restrictions for this ID:

• Only Numeric
• Maximum 10 digits
• Possible to create up

Answer 1

This may be a crazy idea but its an idea :).

• First generate UUID and get a string representation of it with java.util.UUID.randomUUID().toString()

• Second convert generated string to byte array (byte[])

• Then convert it to long buffer: java.nio.ByteBuffer.wrap( byte digest[] ).asLongBuffer().get()

• Truncate to 10 digits

Not sure about uniqueness of that approach tho, I know that you can rely on uniqueness of UUIDs but haven't checked how unique are they converted and truncated to 10 digits long number.

Example was taken from JavaRanch, maybe there is more.

Edit: As you are limited to 10 digits maybe simple random generator would be enough for you, have a look into that quesion/answers on SO: Java: random long number in 0 <= x < n range