List.reverse could detect a singleton list and return itself, thereby avoiding 
an unnecesary  customer  creation for the new list.

  xxxxx@xxxxx   2005-05-08 20:43:58 GMT

N/A

Both empty and singleton lists can be returned unchanged by reverse.

However, there is one gotcha that needs to be addressed with this fix. List.prependList assumes that reverse always returns a new list, because it reuses the List objects by zapping their tail pointer, rather than creating new objects.  The workaround for that is simple: prependList already checks for either list being empty, so it is simply necessary to also check if the list being prepended is a singleton, and handle that case directly.

There appear to be no other problem cases for reverse() in javac.
Posted Date : 2006-07-14 23:11:28.0