title: What is the meaning of Possible null pointer dereference in findbug?
body: <p>I am using Sonar and I have got this kind of violation from it for a peace of my code:</p>
  
  <pre><code> Correctness - Possible null pointer dereference  
  </code></pre>
  
  <p>Has anyone know about this rule in findbugs? I searched a lot but I can not find a good sample code (in Java) which describe this rule, unfortunately findbugs site did not have any sample code or good description about this rule. </p>
  
  <p>Why does this violation appear?</p>