Java Stream How to - Reduce to sum

The following code shows how to reduce to sum.

Example

//from  w w w .jav  a2s .c  om
import java.util.Arrays;
import java.util.List;

public class Main {
  public static void main(String...args){
    List<Integer> numbers = Arrays.asList(3,4,5,1,2);
    int sum = numbers.stream().reduce(0, (a, b) -> a + b);
    System.out.println(sum);
  }
}

The code above generates the following result.