What's the simplest way to convert a String Array to an int Array using Java 8? [closed]

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I'm currently learning how to use Java and my friend told me that this block of code can be simplified when using Java 8. He pointed out that the parseIntArray could be simplified. How would you do this in Java 8?

public class Solution {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String[] tokens = input.nextLine().split(" ");
        int[] ints = parseIntArray(tokens);
    }

    static int[] parseIntArray(String[] arr) {
        int[] ints = new int[arr.length];
        for (int i = 0; i < ints.length; i++) {
            ints[i] = Integer.parseInt(arr[i]);
        }
        return ints;
    }
}

Does this answer your question? Converting a String Array to an Int array — Mr. Jain
– Mr. Jain, Commented Aug 8, 2020 at 17:17

Boris the Spider · Accepted Answer · 2014-10-11 10:10:48Z

47

For example:

static int[] parseIntArray(String[] arr) {
    return Stream.of(arr).mapToInt(Integer::parseInt).toArray();
}

So take a Stream of the String[]. Use mapToInt to call Integer.parseInt for each element and convert to an int. Then simply call toArray on the resultant IntStream to return the array.

answered Oct 11, 2014 at 10:10

Boris the Spider

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10 Comments

Irvin Denzel Torcuato Over a year ago

Wow! Is this java? Certainly this is tidier than my solution. Thank you for the fast response!

Boris the Spider Over a year ago

@IrvinDenzelTorcuato Java 8, yes.

Boris the Spider Over a year ago

@MohammadFaisal it's Java 8 syntax, read about it in the tutorial.

Ridhuvarshan Over a year ago

How do you get it as Integer[] array instead of int[] array?

Boris the Spider Over a year ago

What have you tried @Ridhuvarshan? Why didn't it work?

|

Holger · Accepted Answer · 2014-10-11 10:23:20Z

20

You may skip creating the token String[] array:

Pattern.compile(" ")
       .splitAsStream(input.nextLine()).mapToInt(Integer::parseInt).toArray();

The result of Pattern.compile(" ") may be remembered and reused, of course.

answered Oct 11, 2014 at 10:23

Holger

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1 Comment

Boris the Spider Over a year ago

Wow, nifty. Didn't know splitAsStream.

Shirkam · Accepted Answer · 2017-11-16 10:16:22Z

3

You could, also, obtain the array directly from a split:

String input; //Obtained somewhere
...
int[] result = Arrays.stream(input.split(" "))
        .mapToInt(Integer::valueOf)
        .toArray();

Here, Arrays has some nice methods to obtain the stream from an array, so you can split it directly in the call. After that, call mapToInt with Integer::valueOf to obtain the IntStream and toArray for your desired int array.

answered Nov 16, 2017 at 10:16

Shirkam

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