2017
September
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String.split(), Java 8 style
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 thanPattern:1 2 3 4
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 versusString.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 usingsplit(), streamed or not, we may get a blank value in some situations, so we need to check for that (notice the calls toString.isEmpty()in both of those implementations). With thePattern-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 