title: Issue with convert NULL to String or to Double Issue
body: <p>I have a query that retrive an object type and convert it to double value. Here is how I did:</p>
  
  <pre><code>Double.valueOf(rs.getObject("price").toString()).doubleValue()));
  </code></pre>
  
  <p>However, if the price data in DB is NULL, I got error: NullPointerException.</p>
  
  <p>How can I deal with it? If it is NULL, i want to just leave it blank. </p>
  
  <p>I guess the issue is when it get null, Java cannot convert to string or to doubleValue(), How can I prevent this happen? </p>