<Swing Dev> Replace concat String to append in StringBuilder parameters

[Claes Redestad]

+1

Some suggestions (mostly nits):

- in places like src/share/classes/java/util/regex/Pattern.java you 
introducesingle-char
   strings which might use a char instead:

-                result.append("|"+next);
+                result.append('|').append(next);

- in places like src/share/classes/sun/security/provider/PolicyFile.java
   you end up with a sequence of String literal appends which could be 
merged into one:

-                sb.append(principalInfo[i][0] + " " +
-                    "\"" + principalInfo[i][1] + "\"");
+                sb.append(principalInfo[i][0]).append(" \"")
+                    .append(principalInfo[i][1]).append('"');

- in some places like src/share/classes/java/text/ChoiceFormat.java
   you end up doing append(""). I guess the empty string concatenation was used as a form
   of primitive-to-string coercion and was probably always redundant already, but care needs
   to be taken that doing the append directly behave as intended.

   I think it should be safe to just remove the empty string append in most cases:

-                result.append(""+choiceLimits[i]);
+                result.append(choiceLimits[i]);

Thanks!

/Claes

On 2014-08-10 23:33, Otávio Gonçalves de Santana wrote:
> *Motivation:* Make another append instead of concat String inside of append
> parameter in StringBuilder class. To avoid an extra StringBuilder created
> for the purpose of concatenating. So it will save memory and will faster
> than concat String.
> Doing a code to benchMark[1], the result is:
>
> Benchmark                                                  Mode   Samples
>        Mean   Mean error    Units
> m.StringBuilderConcatBenchMark.stringBuilder              thrpt        10
>   6317444.705   108673.584    ops/s
> m.StringBuilderConcatBenchMark.stringBuilderWithConcat    thrpt        10
>   3354554.435    68353.924    ops/s
>
> The webrev of all code is:
> https://dl.dropboxusercontent.com/u/16109193/open_jdk/string_builder_concat.zip
> <https://dl.dropboxusercontent.com/u/16109193/open_jdk/string_builder_concat.zip>
>
> [1]
>
> @State(Scope.Thread)
> @OutputTimeUnit(TimeUnit.SECONDS)
> public class StringBuilderConcatBenchMark {
>
>
>          private static final String F = "!!!!";
>   private static final String E = " running in Java ";
> private static final String D = " in the code ";
>   private static final String C = " to try impact ";
> private static final String B = " with some text ";
>   private static final String A = "Doing a test";
>
> @GenerateMicroBenchmark
> public void stringBuilder(BlackHole bh) {
>   bh.consume(createBuilder(A, B, C, D, E, F));
> }
>
> @GenerateMicroBenchmark
>   public void stringBuilderWithConcat(BlackHole bh) {
> bh.consume(createBuilderWithConcat(A, B, C, D, E, F));
>   }
>
> private StringBuilder createBuilder(String... values) {
> StringBuilder text = new StringBuilder();
>   text.append(values[0]).append(values[1])
> .append(values[2]).append(values[3])
> .append(values[4]).append(values[5]);
>   return text;
> }
>   private StringBuilder createBuilderWithConcat(String... values) {
>   StringBuilder text = new StringBuilder();
> text.append(values[0] + values[1])
> .append(values[2] + values[3])
>   .append(values[4]+ values[5]);
> return text;
> }
> }
>