Problem with HashSet Serialization / Cloning

Question

Why is this failing? I am comparing the serialized form of an empty HashSet with the serialized form of its clone created by serialization+deserialization.

import org.apache.commons.lang3.SerializationUtils;
import static org.assertj.core.api.Assertions.assertThat;

...

final HashSet<String> hashSet = new HashSet<>();
assertThat(SerializationUtils.serialize(hashSet))
    .containsExactly(SerializationUtils.serialize(SerializationUtils.clone(hashSet)));

AssertionError will be thrown.

Something must be not correctly serialized/deserialized in a HashSet. Do you have any idea, what exactly? I am Using OpenJDK 8.

just FYI: [What is a raw type and why shouldn't we use it?](https://stackoverflow.com/questions/2770321/what-is-a-raw-type-and-why-shouldnt-we-use-it) — Lino, Dec 03 '20 at 13:05
@Lino thanks. Yep. But it is not relevant for the question. I add a type for it ;) — Gábor Lipták, Dec 03 '20 at 13:19

score 1 · Accepted Answer · answered Dec 03 '20 at 12:45

1

It has something with loadingFactor. If the Hashset is instantiated like this, then it works:

new HashSet(0,0.75f);

answered Dec 03 '20 at 12:45

Gábor Lipták

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You better add this to your original post instead of adding a new answer. – Dorian Gray Dec 03 '20 at 14:04
@DorianGray It's OK to have self-answered questions, https://stackoverflow.com/help/self-answer – fps Dec 03 '20 at 14:14
It doesn't look like an answer. It doesn't explain the problem in the first post. – Dorian Gray Dec 03 '20 at 14:44

Problem with HashSet Serialization / Cloning

1 Answers1