How to find sum of integers in an array List

import java.util.ArrayList;
import java.util.Arrays;

public class SumOfArrayElementsUsingStreams {

	public static void main(String[] args) {

		// Initialize the array with integer values
		ArrayList<Integer> arrList = new ArrayList<Integer>(Arrays.asList(1, 2, 3, 4, 5, 6));
		int sumNums;
		/*
		 * using reduce () -> where a is accumulator, initial value of a is 0 and b is
		 * the each element in the stream
		 */
		sumNums = arrList.stream().reduce(0, (a, b) -> a + b);
		System.out.println("The sum of integers in an array list is= " + sumNums);
	}
}