java.sql.TimeStamp extends java.util.Date. Any object/method, including Calendar, that requires a java.util.Date will accept a java.sql.TimeStamp.
java.sql.Date, java.util.Time and java.sql.TimeStamp all extend java.util.Date for the basic purpose of overriding the toString() method, which outputs the date in either a SQL Date or Timestamp
String.
If you have a java.util.Date object, you can assign it the return value of ResultSet.getDate, ResultSet.getTime and ResultSet.getTimeStamp.