title: What's the difference between StringBuilder and ArrayList<String>?
body: <p>In an interview, I want to build up a new String with some substrings. I argued that <code>ArrayList&lt;String&gt;</code> is almost the same as <code>StringBuilder</code>, but the interviewer said I should always use <code>StringBuilder</code> if I need to deal with String. I think the time complexity of adding/removing functions between them are the same.</p>