title: SimpleJson: String to JSONArray
body: <p>I get the following JSON:</p>
  
  <pre><code>[
    {
      "user_id": "someValue"
    }
  ]
  </code></pre>
  
  <p>It's saved inside a String.</p>
  
  <p>I would like to convert it to a <code>JSONObject</code> which fails (as the constructor assumes a JSON to start with <code>{</code>). As this doesn't seem to be possible I'd like to convert it to a <code>JSONArray</code>. How can I do that with SimpleJson?</p>