It is supposed to be generally preferable to use a StringBuilder for string concatenation in Java. Is this always the case?
What I mean is this: Is the overhead of creating a StringBuilder object, calling the append() method and finally toString() already smaller then concatenating existing strings with the + operator for two strings, or is it only advisable for more (than two) strings?
If there is such a threshold, what does it depend on (perhaps the string length, but in which way)?
And finally, would you trade the readability and conciseness of the + concatenation for the performance of the StringBuilder in smaller cases like two, three or four strings?