title: Java - 2 Way 'Has A' Relationship
body: <p>I have just started a project to make my employer a management software. I have a niggling, but potentially simple, query that I can't seem to find any information on. </p>
  
  <p>Is it prudent/good practice to have a 2 way 'has a' relationship between objects. So can, for example, a <code>Client</code> object 'have a' <code>Site</code>, and then the <code>Site</code> 'has a' <code>Client</code>, where the <code>Client</code> object is the <code>Client</code> that 'has' the <code>Site</code>?</p>
  
  <pre><code>public class Client {
      Site site;
  }
  
  public class Site {
      Client client;
  }
  </code></pre>
  
  <p>Is there anything objectionable (no pun intended) to this, or is it fine? I am currently creating a mock-up UML for the project, and this has been bothering me.</p>