title: Replace a non-specific substring in a string
body: <p>Well I'm trying to descover how to replace in a string like this:
  <code>String user ="123124.Ken:000";</code> the substring <code>.Ken:000</code> with for example
  <code>.Diana:999</code>. I think that there is something in using <code>indexOf()</code> of that <code>'.'</code> character but I don't know how to replace from that <code>indexOf()</code> to the end of <code>user</code> string.</p>