+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;
}
}
