Useful to store thread-local date format instances. This class is
intended for servlets/molly pages. Instead of static get/set methods,
this class must be instantiated and the instance methods used to get/set
the calendar object. This allows multiple instances of this class in the
webapp, with each instance being able to get/set a separate calendar. [If
the methods in this class were static, then only 1 calendar could be
get/set per thread].
Each thread must remember to individually create a
separate calendar instance and store it via the set method. The
usage idiom is:
//WebApp has a map of ThreadLocalDateFormat's and also a instance variable
//pointing to a default ThreadLocalDateFormat
ThreadLocalDateFormat mydf = WebApp.getThreadLocalDateFormat("foo");
if (mydf.isNull()) {
mydf.set(DateFormat.getInstance());
}
DateFormat df = mydf.get();
Note, the lines in red are always needed anywhere/anytime this class is used.
(note, it just so happens that the
DateFormat.getInstance() returns (at
least for now) a new object every time it is called, which is why it is
being used in the example above, else we would have to manually create a new
DateFormat instance instead).