java - LinkedHashMap LRU Cache - Determine what values are removed? -


background information

you can make lru cache linkedhashmap shown at link. basically, just:

  • extend linked hash map.
  • provide capacity parameter.
  • initialize super class (linkedhashmap) parameters tell capacity, scaling factor (which should never used), , keep items in insertion/reference order.
  • override removeeldestentry remove oldest entry when capacity breached.

my question

this pretty standard lru cache implementation. 1 thing can't figure out how how notified when linkedhashmap removes entry due not being used enough.

i know can make removeeldestentry provide form of notification... there way retrieve element removed cache right when new 1 inserted (put) underlying map? alternatively, there way query last item removed cache?

is there way retrieve element removed cache right when new 1 inserted (put) underlying map?

the removeeldestentry notified of entry removed. can add listener method calls if want make dynamically configurable.

from javadoc

protected boolean removeeldestentry(map.entry eldest)

eldest - least inserted entry in map, or if access-ordered map, least accessed entry. entry removed method returns true. if map empty prior put or putall invocation resulting in invocation, entry inserted; in other words, if map contains single entry, eldest entry newest.

.

is there way query last item removed cache?

the last item removed has been removed, have sub-class store entry in field can retrieve later.


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