 <p>This has nothing to do with calling revalidate as recommended by another and likely has all to do with calling a method on the wrong object. In your showEmployeesActionPerformed method you create a new Company object, one that is not visualized. The key is to call this method on the proper reference, on the visualized GUI. You do this by passing a reference to the visualized GUI object into the class that is wanting to call methods on it. This can be done via a setCompany method:</p> <pre><code>setCompany(Company company) { this.company = company); } </code></pre> <p>or via a constructor parameter.</p>