title: Pattern in regexp
body: <p>I have a pattern like:</p>
  
  <pre><code>string [number|number]
  </code></pre>
  
  <p>I want validate with RegExp in Java.</p>
  
  <p>Case valid: <code>"blablabla blabla blabla [12|1234]"</code></p>
  
  <p>Any other would be invalid.</p>
  
  <p>I don't realise how to do it.</p>