Get Employees before and after specific date of joining from List of Employees with Java stream

Question

I have List of Employees with different joining dates. I want to Get Employees before and after specific date of joining from List using streams.

i tried following code,

 List<Employee> employeeListAfter = employeeList.stream()
                .filter(e -> e.joiningDate.isAfter(specificDate))
                .collect(Collectors.toList());

List<Employee> employeeListBefore = employeeList.stream()
        .filter(e -> e.joiningDate.isBefore(specificDate))
        .collect(Collectors.toList());

class Employee{
    int id;
    String name;
    LocalDate joiningDate;
}

Is there any way to do this in single stream?

Answer 1

You can use partitioningBy as below,

Map<Boolean, List<Employee>> listMap = employeeList.stream()
        .collect(Collectors.partitioningBy(e -> e.joiningDate.isAfter(specificDate)));

List<Employee> employeeListAfter = listMap.get(true);
List<Employee> employeeListBefore = listMap.get(false);

partitioningBy Returns a Collector which partitions the input elements according to a Predicate, and organizes them into a Map<Boolean, List<T>>

Note that this won't handle employees with specificDate.