title: Java: String concat vs StringBuilder - optimised, so what should I do?
body: <p>In <a href="https://stackoverflow.com/a/1532499/1154376">this answer</a>, it says (implies) that String concatenation is optimised into StringBuilder operations anyway, so when I write my code, is there any reason to write StringBuilder code in the source? Note that my use case is different from the OP's question, as I am concatenating/appending hundreds-thousands of lines.</p>
  
  <p>To make myself clearer: I am well-aware about the differences of each, it's just that I don't know if it's worth actually writing StringBuilder code because it's less readable and when its supposedly slower cousin, the String class, is converted automagically in the compilation process anyway.</p>