On Sun, 20 Feb 2022 18:20:27 GMT, liach <d...@openjdk.java.net> wrote:
>> XenoAmess has updated the pull request incrementally with three additional
>> commits since the last revision:
>>
>> - refine test
>> - 1. optimize IdentityHashMap that when calling ::new(Map), do not call
>> map.size() twice but once.
>> 2. delete the this((int) ((1 + m.size()) * 1.1)); as it makes the table
>> over-allocate when size = 19.
>> - refine test
>
> src/java.base/share/classes/java/util/IdentityHashMap.java line 281:
>
>> 279: * @throws NullPointerException if the specified map is null
>> 280: */
>> 281: private IdentityHashMap(Map<? extends K, ? extends V> map, int
>> expectedSize) {
>
> Why are you writing a new constructor when you can just change the old call
> to `this(m.size());`?
@liach because I don't like to call m.size() twice.
the original codes did so: one call at the `public IdentityHashMap(Map<?
extends K, ? extends V> map)` , and the second inside of `putAll`.
well in most Map implementations `size()` seems O1, and returns a single int
number field, but it actually defers in some Map implementations.
But java grammar do not allow me to make a local variable before calling
constructor in a constructor.
In other words, `this()` must be the first line in a constructor.
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PR: https://git.openjdk.java.net/jdk/pull/7431
