title: Java Regular expression to extract text from square bracket
body: <p>How can I extract the text with in square brackets if it contains only dot and no other special character?
  For example I want to extract "com.package.file" from</p>
  
  <pre><code> "ERR|appLogger|[Manager|Request]RequestFailed[com.package.file]uploading[com.file_upload]"
  </code></pre>