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Programming-Idioms

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  • Java

Idiom #356 Parse list of integers

Create the list of integers items for the string s containing integers separated by one or more whitespace characters (space, tab, newline).

import java.util.Scanner;
Scanner t = new Scanner(s);
int items[] = t.tokens()
    .mapToInt(Integer::parseInt)
    .toArray();
t.close();
import java.util.List;
import java.util.Scanner;
Scanner t = new Scanner(s);
List<Integer> items = t.tokens()
    .map(Integer::parseInt)
    .toList();
t.close();

Note, the `toList` method will return an immutable `List`.
import java.util.Scanner;
Scanner t = new Scanner(s);
Integer items[] = t.tokens()
    .map(Integer::valueOf)
    .toArray(Integer[]::new);
t.close();
import static java.util.stream.Collectors.toCollection;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
Scanner t = new Scanner(s);
List<Integer> items = t.tokens()
    .map(Integer::parseInt)
    .collect(toCollection(ArrayList::new));
t.close();
import "fmt"
import "strconv"
parts := strings.Fields(s)
items := make([]int, len(parts))
for i, part := range parts {
	v, err := strconv.Atoi(part)
	if err != nil {
		return err
	}
	items[i] = v
}

strings.Fields treats repeated spaces as a single separator.

New implementation...
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