Filter on map of map

Question

I have below map of map and want to filter it based on a value. The result should be assigned back to same map. Please let know what is the best approach for this.

Map<String, Map<String, Employee>> employeeMap;

<
 dep1, <"empid11", employee11> <"empid12",employee12>
 dep2, <"empid21", employee21> <"empid22",employee22>
>

Filter: employee.getState="MI"

I tried like below but i was not able to access the employee object

currentMap = currentMap.entrySet().stream()
            **.filter(p->p.getValue().getState().equals("MI"))**                    
            .collect(Collectors.toMap(p -> p.getKey(),p->p.getValue()));

Answer 1

If you want to modify the map in place (and that it allows so), you can use forEach to iterate over the entries of the map, and then use removeIf for each values of the inner maps to remove the employees that satisfy the predicate:

employeeMap.forEach((k, v) -> v.values().removeIf(e -> e.getState().equals("MI")));

Otherwise, what you can do is to use the toMap collector, where the function to map the values takes care of removing the concerned employees by iterating over the entry set of the inner maps:

Map<String, Map<String, Employee>> employeeMap =
    employeeMap.entrySet()
               .stream()
               .collect(toMap(Map.Entry::getKey,
                              e -> e.getValue().entrySet().stream().filter(emp -> !emp.getValue().getState().equals("MI")).collect(toMap(Map.Entry::getKey, Map.Entry::getValue))));