sum of list java

1doubleList.stream().reduce((a,b)->a+b).get();
2

1int sum = (list.stream().
2        mapToInt(i -> i.intValue()).sum()

1double sum = 0;
2for(int i = 0; i < m.size(); i++)
3    sum += m.get(i);
4return sum;
5

1//If you have a List<Integer>
2int sum = list.stream().mapToInt(Integer::intValue).sum();
3
4//If it's an int[]
5int sum = IntStream.of(a).sum();