String.split(), Java 8 style
Wednesday, September 27, 2017 |Today I found myself with a common problem: I had a delimited string of an unknown number of parts that that I needed split apart and process. Prior to Java 8, implementing that might looked something like this:
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for (String part : string.split("\\n")) {
if (!myList.contains(part)) {
if (!part.isEmpty()) {
myList.add(part);
}
}
}
While that works and seems to be pretty efficient, I felt it could use a stream makeover, as I find the stream operations to be clearer and more concise. What I ended up with was something like this:
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Pattern.compile("\\n")
.splitAsStream(string)
.filter(s -> !myList.contains(s))
.forEach( s -> myList.add(s));
I could also have used Arrays.stream() rather than Pattern:
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Arrays.stream(string.split("\\" + DELIMITER))
.filter(s -> !myList.contains(s))
.filter(s -> !s.isEmpty())
.forEach(s -> myList.add(s));
I haven’t done any profiling to see if Pattern.compile() has any non-negligible
performance impact versus String.split() (and I probably won’t, but you can easily
"cache" the compiled pattern in an instance or static variable if needed :), but I will
point out this difference: when using split(), streamed or not, we may get a blank
value in some situations, so we need to check for that (notice the calls to
String.isEmpty() in both of those implementations). With the Pattern-based
implementation, we don’t have that problem.
At any rate, there you have it: you can convert String.split() to a stream-based
implementation fairly easily, and, I think, get more readable code out of it. Any
performance implications are left as an exercise for the reader. :)
My name is Jason Lee. I am a software developer living in the middle of Oklahoma. I’ve been a professional developer since 1997,
using a variety of languages, including Java, Javascript, PHP, Python, Delphi, and even a bit of C#. I currently work for Red Hat
on the WildFly/EAP team, where, among other things, I maintain integrations for some MicroProfile specs, OpenTelemetry, Micrometer,
Jakarta Faces, and Bean Validation. (Full resume 