title: Convert String Number to Double and then correct format in Java
body: <p>Ok so I have been searching for 2 hours on this and please before jumping to mark this as a duplicate have a look at the question.</p>
  
  <p>I have a number of strings which contain number</p>
  
  <p>Numbers will all be like this </p>
  
  <pre><code>String one = 611960;
  String two = 64850;
  String three = 0;
  String four = 636;
  </code></pre>
  
  <p>I want to be able to have these in the correct format as in</p>
  
  <p>6,119.60
  648.50
  0.00
  6.36</p>
  
  <p>I have tried</p>
  
  <pre><code>DecimalFormat df = new DecimalFormat("#,###,###,##0.00");
  </code></pre>
  
  <p>and converting the String to a double e.g.</p>
  
  <pre><code>double amount = Double.parseDouble(one);
  </code></pre>
  
  <p>which seems to give 611960.0</p>
  
  <p>then I do </p>
  
  <pre><code>String gfeeOne = df.format(amount);
  </code></pre>
  
  <p>which in turn gives 611,960.00</p>
  
  <p>So at this stage I'm a bit lost. This should be straightforward and maybe I'm getting lost. I want to cover all cases up to something like this 1000000000 e.g. 1,000,000,000.00</p>
  
  <p>Help very much appreciated</p>