title: regular expression to find repeated words in a sentence
body: <p>I was trying to write a regular expressions to find repeated words in a sentence.
  Well, I tried using this expression:</p>
  
  <pre><code>\b(\w+)\b.*?\1
  </code></pre>
  
  <p>to select 3x 'hello', 2x 'are', and 2x 'you' from the sentence <code>"Hello how in the Hello world are you ? are you okay? Hello"</code>, which I know is clearly wrong, since it takes entire group of words into consideration instead of one particular word!<br>
  So could you correct my expression or come up with your own solution?<br>
  I'm using <code>Matcher</code> class to try to find out number of occurrence of a given word using count variable in while loop of <code>matcher.find()</code>.</p>