blocks|key|637692|text|您可以使用Map通过散列快速检索元素。根据定义，Map是无序的，谈论索引没有多大意义。使用LinkedHashMap可能是有用的，因为它保证在迭代时保留插入顺序，尽管按索引访问元素仍然需要一些额外的处理，如下所示：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|637693|map.entrySet().toArray()[index]+//+mind+the+casts,+etc.|code-block|syntax|javascript|637694|如果您的映射很少发生更改，那么如果您缓存数组并检查映射的大小在按索引访问条目之前是否已经更改，则上面的内容将很好地工作，只有在检测到大小更改时才创建新的数组。另一方面，如果映射更改频繁，则需要在每次访问时重新创建数组，从而创建性能较差的数据结构。|637695|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/7/docs/api/java/util/LinkedHashMap.html^0|5|3|O|3|19|D|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|13|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

You can use a <code>Map</code> for fast retrieval of elements by hash. By definition, a <code>Map</code> is unordered and talking about indexes doesn't make much sense. Using a <a href="http://docs.oracle.com/javase/7/docs/api/java/util/LinkedHashMap.html" rel="nofollow">LinkedHashMap</a> might be of use, since it guarantees that insertion order is preserved at iteration time, although accessing an element by index will still need some extra processing, something like this:

<pre><code>map.entrySet().toArray()[index] // mind the casts, etc.
</code></pre>

If your map changes infrequently, the above will work nicely if you cache the array and check to see if the size of the map has changed before accessing an entry by index, creating a new array only when a change in size has been detected. On the other hand, if the map changes frequently you'd need to re-create the array at each access, creating a poorly performing data structure.

blocks|key|639693|text|我想你可以试试LinkedHashSet。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|639694|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/6/docs/api/java/util/LinkedHashSet.html^0|7|D|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

You can try <a href="http://docs.oracle.com/javase/6/docs/api/java/util/LinkedHashSet.html" rel="nofollow">LinkedHashSet</a>, I think.

blocks|key|1295484|text|使用LinkedHashMap.这将允许您通过键检索元素。此外，您还可以检索与存储在其中的元素顺序相同的元素。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|1295485|entityMap^0|2|D|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

use LinkedHashMap. This will let you retrieve the elements through key. And also you can retrieve the elements in the same sequence as you stored in it.

blocks|key|637741|text|我想你是在找LinkedHashMap|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|637742|从医生那里：|637743|哈希表和映射接口的链接列表实现，具有可预测的迭代顺序。此实现与HashMap不同的是，它维护一个通过其所有条目运行的双链接列表。这个链表定义了迭代顺序，这通常是将键插入到映射中的顺序(插入顺序)。注意，如果将键重新插入到映射中，则插入顺序不会受到影响。(如果调用m.put(k，v)时，m.containsKey(k)将在调用之前返回true，则密钥k将重新插入到映射m中。)|637744|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/1.4.2/docs/api/java/util/LinkedHashMap.html^0|6|D|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@$A|Q|B|R|1|S]]|C|$]]|$1|D|3|E|5|6|7|T|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|U|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|I|$J|$5|K|L|M|C|$N|O]]]]

I think you're looking for <a href="http://docs.oracle.com/javase/1.4.2/docs/api/java/util/LinkedHashMap.html" rel="nofollow">LinkedHashMap</a>

From the docs:

Hash table and linked list implementation of the Map interface, with predictable iteration order. This implementation differs from HashMap in that it maintains a doubly-linked list running through all of its entries. This linked list defines the iteration ordering, which is normally the order in which keys were inserted into the map (insertion-order). Note that insertion order is not affected if a key is re-inserted into the map. (A key k is reinserted into a map m if m.put(k, v) is invoked when m.containsKey(k) would return true immediately prior to the invocation.)

Is there any class in Java, which holds an array of elements both in order and optimized for fast searching?

I.e. I need to retrieve elements both by numeric index (like in <code>Vector</code>) and by hash (like in <code>HashMap</code>).

LinkedHashMap does not match

I think <code>LinkedHashMap</code> does not match since it guarantees order, but does not allow fast accessing by index (position number). According to description, it will require to traverse entire chain to find a given position. This is what any <code>Collection</code> can with iterator.

EDIT 2

I.e. both searching by key and by index should be fast, not only by key.

Both hashed and indexed list or array?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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Java中是否有一个类，它按照顺序保存了一个元素数组，并为快速搜索进行了优化？也就是说，我需要通过数字索引(如Vector)和散列(如HashMap)检索元素。LinkedHashMap与不匹配我认为LinkedHashMap不匹配，因为它保证顺序，但不允许通过索引(位置号)进行快速访问。根据描述，需要遍历整个链才能找...

问散列和索引列表或数组？
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