title: Java regular expression to match a alphanumeric string of length greater than one which has atleast one different character
body: <p>In the below regular expression</p>
  
  <pre><code>^(?:(?!(\w)\1\b).)*$ 
  </code></pre>
  
  <p>Does not match string which has last two characters same. For example 1233</p>
  
  <p>What is the issue? </p>