https://foojayio.github.io/website/today/author/victor-rentea/Articles written by Victor Rentea on foojay.io - Friends of OpenJDKHugoen-usTue, 22 Dec 2020 10:14:41 +0000https://foojayio.github.io/website/today/avoiding-nullpointerexception/Tue, 22 Dec 2020 10:14:41 +0000https://foojayio.github.io/website/today/avoiding-nullpointerexception/<p>The terrible <code>NullPointerException</code> (NPE for short) is the most frequent Java exception occurring in production, according to <a href="https://www.overops.com/blog/the-top-10-exceptions-types-in-production-java-applications-based-on-1b-events/" target="_blank" rel="noopener noreferrer">a 2016 study</a> . In this article we&rsquo;ll explore the main techniques to fight it: the self-validating model and the <code>Optional</code> wrapper.</p> <h2 id="h2-0-self-validating-model">Self-Validating Model</h2> <p>Imagine a business rule: every Customer has to have a birth date set. There are a number of ways to implement this constraint: validating the user data on the create and update use-cases, enforcing it via <code>NOT NULL</code> database constraint and/or implementing the null-check right in the constructor of the Customer entity. In this article we&rsquo;ll explore the last one.</p>