Extracting an array of integers from a string, using java-streams

Question

I'm having a hard time understanding why this code returns an Object[] and not an int[] ("line" is a string I read off a file that looks like "1 2 3 4 5").

Arrays.stream(line.split(" ")).map(Integer::valueOf).collect(toList()).toArray()

I hope you can help me understand, thank you !

DuncG · Accepted Answer · 2022-03-12 13:00:35Z

2

The stream is of type Object, use mapToInt to convert as int:

Arrays.stream(line.split(" ")).mapToInt(Integer::parseInt).toArray()

edited Mar 12, 2022 at 13:00

answered Mar 12, 2022 at 12:57

DuncG

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2 Comments

Shawn Over a year ago

Pattern.compile(" ").splitAsStream(line).mapToInt(... avoids the temporary array, fwiw.

Holger Over a year ago

@Shawn but this only pays of for a rather large number of substrings, as otherwise, String.split is significantly faster than the regex engine when the pattern consists of a single ordinary character.

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