Using an array of arrays.
package com.logicbig.example.stream;
import java.util.Arrays;
import java.util.stream.LongStream;
public class FlatMapToLongExample2 {
public static void main(String... args) {
String[][] arrayOfArrays = {{"1", "2"}, {"5", "6"}, {"3", "4"}};
LongStream longStream = Arrays.stream(arrayOfArrays)
.flatMapToLong(childArray -> Arrays.stream(childArray)
.mapToLong(Integer::new));
long sum = longStream.peek(System.out::println)
.sum();
System.out.println("sum: " + sum);
}
}
Output
1
2
5
6
3
4
sum: 21