Simple function java String to Int / Reverse
<p>I want to generate a <code>String</code> with <code>11</code> digits from an ID.<br>
For example: 
an account with an <code>ID=12</code> would give <code>00000000012</code></p>

<p>And after that I need to retrieve this id from the string.</p>

<p>For example: 
a string with <code>00000000022</code> give an <code>ID=22</code></p>
