element list littl complex simpl lookup index list contain interfac hashtabl lookup lot faster linear search add result linear search hashtabl time need checklist exist param cl lookup checklist lookup checklist cl list contain cl checklist list cl let search enumer enumer list kei enumer element object clazz enumer element intf cl interfac intf length intf equal clazz checklist chlist checklist list clazz enter speed search list cl chlist chlist 