I am new using stream
in java
and would like to know if there exists a way to optimize this code. I am confused when I should use map
or filter in this situation
public Active get(List<Person> personList){
Active a = null;
for(Person person:personList){
if(person.getActives() != null && !person.getActives().isEmpty()){
for(Active active: person.getActives()){
if(active.getStatus().equals(SOME_VALUE)){
if (a == null || a.getDueDate().isAfter(active.getDueDate())) {
a = active;
}
}
}
}
}
return a;
}
Active a = personList.stream()
.filter(person -> person.getActives() != null && !person.getActives().isEmpty()
.flatMap(person -> person.getActivities())
.filter(activity -> active.getStatus().equals(SOME_VALUE))
.reduce(null, (pos_a, activity) ->
(pos_a == null || a.getDueDate().isAfter(active.getDueDate()))? activity: pos_a)
return a;
This will get all the Persons that have Activities, stream all the Activity's (flatMap) and filter those on their status and then reduce the list keeping the oldest one
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