# How to compute sum for each list in Map<>?

This is my map `Map<LocalDate,List<Integer>> map = new LinkedHashMap<>();`

Question 1: How to compute the sum for each list in Map<>

Output of the Map<>

``````2020-01-22 [0, 0, 7, 0, 0, 0, 0, 0, 3, 8, 0, 4,0]
2020-01-23 [0, 0, 7, 0, 0, 0, 0, 0, 3, 0, 0, 4,0]
2020-01-24 [0, 0, 7, 0, 0, 0, 0, 0, 3, 0, 0, 5,0]
2020-01-25 [0, 0, 8, 0, 0, 0, 0, 0, 3, 0, 0, 4,0]
2020-01-26 [0, 0, 7, 0, 0, 0, 0, 0, 3, 0, 0, 8,0]
2020-01-27 [0, 0, 9, 0, 0, 0, 0, 0, 3, 0, 0, 4,0]
``````

My try

``````Map<LocalDate,List<Integer>> map = new LinkedHashMap<>();
List<Integer> integerList =map
.values()
.stream()
.map(l->{
int sum = l
.stream()
.mapToInt(Integer::intValue)
.sum();
return sum;
}).collect(Collectors.toList());
``````

The code here that I have tried, I can only form the new list and
calculate it. But I would like the date and its sum of num display at the same time

Desired Output (Calculate and display the sum for each list)

``````2020-01-22 [22]
2020-01-23 [14]
2020-01-24 [15]
2020-01-25 [14]
2020-01-26 [18]
2020-01-27 [16]
``````

### >Solution :

You could try this

``````Map<LocalDate,Integer> result = new LinkedHashMap<>();
map.forEach((key, value) -> {
result.put(key,value.stream().mapToInt(Integer::intValue).sum());
});
``````