Claude
682b7b067c
Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_017ic4b66uwsWr9B1ouyrzUh
23 lines
793 B
Plaintext
23 lines
793 B
Plaintext
== what the JDK uses ==
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"hello".hashCode() = 99162322
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31*h + c over "hello" = 99162322
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List.of(1,2,3).hashCode() = 30817
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Arrays.hashCode({1,2,3}) = 30817
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Objects.hash(1,2,3) = 30817
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Set.of(1,2,3).hashCode() = 6 (sum of elements)
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Map.of(1,2).hashCode() = 3 (key^value per entry, summed)
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== Objects.hash(...) traps ==
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Objects.hash("a") vs "a".hashCode() = 128 vs 97
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Objects.hash(1, 2) == Objects.hash(2, 1) ? false
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Objects.hash() (no args) = 1
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Objects.hash((Object) null) = 31
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== Arrays as fields ==
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x.equals(y) = false, Arrays.equals = true
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x.hashCode() == y.hashCode() ? false
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Arrays.hashCode equal ? true
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== equal hashCodes do not mean equal objects ==
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"Aa".hashCode() = 2112, "BB".hashCode() = 2112, equal strings? false
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