Java嵌入式DB中的mapdb

Question

mapdb中expireMaxSize(1000)的用途是什么？

    code>>HTreeMap cache = db
    .hashMap("cache")
    .expireMaxSize(1000)
    .create();



HTreeMap cache = db
        .hashMap("cache")
        .expireMaxSize(1000)
        .create();

HTreeMap cache = db
        .hashMap("cache")
        .expireMaxSize(1000)
        .create();