Suggestion: Add the method isEmpty in the classes StringBuilder and StringBuffer (original) (raw)

Hildeberto Mendonça me at hildeberto.com
Mon Feb 11 15:39:00 UTC 2013

On Mon, Feb 11, 2013 at 3:29 PM, Ulf Zibis <Ulf.Zibis at cosoco.de> wrote:

Am 11.02.2013 12:54, schrieb Hildeberto Mendonça:

we have a scenario where a project with approximately 500K lines of code is going through a large refactoring. One of the changes was to replace string concatenations in loops by StringBuilder.

Are you aware, that behind the scenes, String concatenations are automatically internally replaced from javac by StringBuilder invocations, so in the end you might have less readable code, which is still not faster than before.

Yes, I am. On my understanding the compiler can handle that with concatenations like this:

str += "text" + "another" + str2;

but I'm not sure it happens when concatenations are more complex, such as the hypothetical example below:

if(str.isEmpty()) { str = "best cars: "; boolean firstCar = true; for(Car car: cars) { if(firstCar) { firstCar = false; } else { str += ", "; } str += car.getName();

  if(car.getBrand() != null) {
     str += " - " + car.getBrand();
  }

} str += "."; }

I believe, in each iteration, the String is converted to a StringBuilder, appended to, and converted back to a String.

Thanks for the feedback.

-- Hildeberto Mendonça, Ph.D Blog: http://www.hildeberto.com Twitter: https://twitter.com/htmfilho <http://www.cejug.org>

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