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POJava: Only check hashCode in equals() of immutable object
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copied!<p>I have an immutable object, for example a node in the Cartesian space. The class is immutable, so I cache the <code>hashCode</code> for very fast hashing. </p> <pre><code>private final int hashCode; private final double x, y, z; public Node(final double x, final double y, final double z) { this.x = x; this.y = y; this.z = z; this.hashCode = Objects.hashCode(this.x, this.y, this.z); } @Override public boolean equals(final Object obj) { if (this == obj) { return true; } if (obj == null) { return false; } if (!(obj instanceof Node)) { return false; } final Node other = (Node) obj; return Objects.equal(this.x, other.x) && Objects.equal(this.y, other.y) && Objects.equal(this.z, other.z); } @Override public int hashCode() { return this.hashCode; } </code></pre> <p>Since the <code>hashCode</code> is unique and dependent on all fields of the class AND the class is Immutable, would it be correct to only check <code>Node</code> equality based on the <code>hashCode</code>?</p> <pre><code>@Override public boolean equals(final Object obj) { if (this == obj) { return true; } if (obj == null) { return false; } if (!(obj instanceof Node)) { return false; } final Node other = (Node) obj; return this.hashCode == other.hashCode; } </code></pre> <p>This passes all Unit Tests I have written about the properties of <code>equals()</code> and <code>hashCode()</code> and their interaction, but perhaps there is something I am missing?</p> <p>Note: <code>Objects.hashCode()</code> and <code>Objects.equal()</code> are Guava classes helpful for the respective methods.</p>

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