title: How to replace first few characters in java?
body: <p>I have a situation where i have to replace first 4 characters of a string to 'x'.</p>
  
  <p>The original data is '12345678'. I want to replace to 'xxxx5678'.</p>
  
  <p>I am actually using Jasper Reports and this is my field:</p>
  
  <pre><code>$F{obj.contact_id.hisher_member_id}
  </code></pre>
  
  <p>Any suggestion will be highly appreciated.</p>