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なんとかMapの違いを簡単にメモ

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Mapインターフェースの実装がいろいろあってどの実装がどういう特徴だったかを簡単にメモ

EnumMap

keyにEnum型を指定できる。

HashMap

普遍的なMapの実装

ConcurrentHashMap

スレッドセーフなHashMap

HashTable

古いJavaのためのものに残っている。
HashMapとはkey値にnullを許容しないぐらいの違い。

IdentityHashMap

key値の比較に==を用いる(同一インスタンスであること)Map実装。

LinkedHashMap

順序保証がある(挿入順)Map実装

TreeMap

決められた順番でkeyを保持する。
(無指定の時、KeyはComparableインターフェースを実装する必要がある。)

ConcurrentSkipListMap

スレッドセーフなTreeMap

WeakHashMap

keyへの参照がなくなった時、valueも削除されるHashMap


参考元
https://docs.oracle.com/javase/jp/7/api/java/util/Map.html

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