Java – Creating a lock on List or Hastable

A List of String or Hastable of (String,String) type that contains certain values.
I have situation where multiple threads are running and I want each thread to use only one of the values from the above mentioned lists.

Example:
List – Set1,Set2,Set3

If Thread1 is using Set1 and thread2 tries to use one of the values in the list, It should get only Set2 and Set3 as available. Set1 should be available when Thread1 is done.