Collectors summingLong(ToLongFunction mapper) example
Description
Collectors summingLong(ToLongFunction<? super T> mapper)
returns a Collector that produces the sum of a long-valued
function applied to the input elements.
Syntax
summingLong has the following syntax.
public static <T> Collector<T,?,Long> summingLong(ToLongFunction<? super T> mapper)
Example
The following example shows how to use summingLong.
import java.util.stream.Collectors;
import java.util.stream.Stream;
/*from w ww .ja v a2s .c o m*/
public class Main {
public static void main(String[] args) {
Stream<String> s = Stream.of("1","2","3");
long o = s.collect(Collectors.summingLong(n->Long.parseLong(n)));
System.out.println(o);
}
}
The code above generates the following result.
