ivanshuba opened a new pull request, #227:
URL: https://github.com/apache/commons-geometry/pull/227
This commit modifies the `hashCode()` method for `Vector2D` and the
`Vector3D` classes in order to ensure unique values are generated for
non-identical instances of vectors.
The proposed approach for calculating the hash code value is the same that
is used in JTS and HE_Mesh projects. And as quoted in JTS project, this
approach was initially 'borrowed' from the Joshua Bloch book 'Effective Java'
(1st ed, 2008).
In the "Item 9: Always override hashCode when you override equals" he
describes the recipe as follows:
1. Store some constant nonzero value, say 17, in an int variable called
`result`.
2. For each significant field `f` in your object, do the following: a.
Compute an int hash code `c` for the field:
i ...
ii ...
iii If the field is a long, compute (int)(f^(f>>>32))
iv ...
v If the field is a double, compute Double.doublToLongBits(f),
and then hash the resulting long as in step 2.a.iii
vi ...
vii ...
b. Combine the hash code `c` computed in step 2.a into `result` as
follows:
result = 31 * result + c
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