Is java HashMap.clear() and remove() memory effective?
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by Shaman
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Published on 2010-05-11T14:29:56Z
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2010/05/11
14:34 UTC
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Consider the follwing HashMap.clear() code:
/**
* Removes all of the mappings from this map.
* The map will be empty after this call returns.
*/
public void clear() {
modCount++;
Entry[] tab = table;
for (int i = 0; i < tab.length; i++)
tab[i] = null;
size = 0;
}
It seems, that the internal array (table) of Entrys is never shrinked. So, when I add 10000 elements to a map, and after that call map.clear(), it will keep 10000 nulls in it's internal array. So, my question is, how does JVM handle this array of nothing, and thus, is HashMap memory effective?
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