HashMap with multiple values under the same key

Question

Is it possible for us to implement a HashMap with one key and two values. Just as HashMap?

Please do help me, also by telling (if there is no way) any other way to

Answer 1

Using Java Collectors

// Group employees by department
Map> byDept = employees.stream()
                    .collect(Collectors.groupingBy(Employee::getDepartment));

where Department is your key