Java Stream: divide into two lists by boolean predicate

Question

I have a list of employees. They have isActive boolean field. I would like to divide employees into two lists: activeEmployees

Answer 1

If you are open to using a third-party library, this will work using Collectors2.partition from Eclipse Collections.

PartitionMutableList partition =
        employees.stream().collect(
                Collectors2.partition(Employee::isActive, PartitionFastList::new));

List activeEmployees = partition.getSelected();
List formerEmployees = partition.getRejected();

You can also simplify things using ListIterate.

PartitionMutableList partition =
        ListIterate.partition(employees, Employee::isActive);

List activeEmployees = partition.getSelected();
List formerEmployees = partition.getRejected();

PartitionMutableList is a type that extends from PartitionIterable. Every subtype of PartitionIterable has a collection for positive results getSelected() and negative results getRejected().

Note: I am a committer for Eclipse Collections.