Nothing Earth-shattering, I admit, but I've caught people using StringBuffer to concatenate Strings outside of a loop in Java. It was something simple like turning
String msg = "Count = " + count + " of " + total + ".";
into
StringBuffer sb = new StringBuffer("Count = ");
sb.append(count);
sb.append(" of ");
sb.append(total);
sb.append(".");
String msg = sb.toString();
It used to be quite common practice to use the technique in a loop, because it was measurably faster. The thing is, StringBuffer is synchronized, so there's actually extra overhead if you're only concatenating a few Strings. (Not to mention that the difference is absolutely trivial on this scale.) Two other points about this practice:
- StringBuilder is unsynchronized, so should be preferred over StringBuffer in cases where your code can't be called from multiple threads.
- Modern Java compilers will turn readable String concatenation into optimized bytecode for you when it's appropriate anyway.
