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    <p>This is (almost) correct for "technical equality", but not for "natural equality". To achieve top technical equality, you should also test the reflexive <code>o == this</code>. It may happen that the object isn't persisted in DB yet and thus doesn't have a technical ID yet. E.g.</p> <pre><code>public class User { private Long id; @Override public boolean equals(Object object) { return (object instanceof User) &amp;&amp; (id != null) ? id.equals(((User) object).id) : (object == this); } @Override public int hashCode() { return (id != null) ? (User.class.hashCode() + id.hashCode()) : super.hashCode(); } } </code></pre> <p>For "natural equality" you should rather compare all non-technical properties. For "real world entities" this is after all more robust (but also more expensive) than technical equality.</p> <pre><code>public class User { private String name; private Date birth; private int housenumber; private long phonenumber; @Override public boolean equals(Object object) { // Basic checks. if (object == this) return true; if (!(object instanceof User)) return false; // Property checks. User other = (User) object; return Objects.equals(name, other.name) &amp;&amp; Objects.equals(birth, other.birth) &amp;&amp; (housenumber == other.housenumber) &amp;&amp; (phonenumber == other.phonenumber); } @Override public int hashCode() { return Objects.hash(name, birth, housenumber, phonenumber); } } </code></pre> <p>True, that's lot of code when there are a lot of properties. A bit decent IDE (Eclipse, Netbeans, etc) can just autogenerate <code>equals()</code>, <code>hashCode()</code> (and also <code>toString()</code>, getters and setters) for you. Take benefit of it. In Eclipse, rightclick code and peek the <em>Source</em> (Alt+Shift+S) menu option.</p> <h3>See also:</h3> <ul> <li><a href="https://developer.jboss.org/wiki/EqualsandHashCode" rel="nofollow noreferrer">JBoss: Equals and HashCode (in view of <em>persistence</em>)</a></li> <li><a href="https://docs.jboss.org/hibernate/stable/core.old/reference/en/html/persistent-classes-equalshashcode.html" rel="nofollow noreferrer">Hibernate: Persistent Classes - implementing equals() and hashCode()</a></li> <li><a href="https://stackoverflow.com/questions/27581/overriding-equals-and-hashcode-in-java">Related SO question: Overriding equals and hashCode in Java</a> </li> </ul>
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