Java8 Collectors.partitioningBy example 2018-07-06 21:06
Collectors.partitioningBy is used to divide stream into two map. The key of two group are true and false. Two list of values are collections of elements that satisfy the condition. The example code is here.
public class CollectorsPartitioningByClient {
public static void main(String[] args) {
Map<Boolean, List<Integer>> evenMap = IntStream.rangeClosed(1, 10).boxed().collect(Collectors.partitioningBy(n -> n % 2 == 0));
System.out.println(evenMap);
List<User> users = new ArrayList<>();
users.add(new User("Henry", 30));
users.add(new User("Justin", 27));
users.add(new User("Mathew", 26));
Map<Boolean, List<User>> biggerThan30Map = users.stream().collect(Collectors.partitioningBy(u -> u.getAge() >= 30));
System.out.println(biggerThan30Map);
}
}
output
{false=[1, 3, 5, 7, 9], true=[2, 4, 6, 8, 10]}
{false=[User{name='Justin', age=27}, User{name='Mathew', age=26}], true=[User{name='Henry', age=30}]}
EOF