public class HomeroomMix {
public void calculate(String className, int number) {
List<PeopleClass> people = Arrays.asList(
new PeopleClass("DE", "male"),
new PeopleClass("DE", "female"),
new PeopleClass("DE", "n/a"),
new PeopleClass("UK", "female"),
new PeopleClass("UK", "female"),
new PeopleClass("UK", "female"),
new PeopleClass("JP", "trans"),
new PeopleClass("JP", "male")
);
int number_of_groups = number;
Function<PeopleClass, String> discriminator = PeopleClass::getGender;
AtomicInteger index = new AtomicInteger();
List<List<PeopleClass>> groups = new ArrayList<>(people.stream()
.sorted(Comparator.comparing(discriminator))
.collect(Collectors.groupingBy(e -> index.getAndIncrement() % number_of_groups))
.values());
groups.forEach(System.out::println);
}
this is my people class
public PeopleClass(String nationality, String gender) {
this.gender = gender;
this.nationality = nationality;
}
public String getNationality() {
return nationality;
}
public void setNationality(String nationality) {
this.nationality = nationality;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getHomeRoom() {
return homeRoom;
}
public void setHomeRoom(String homeRoom) {
this.homeRoom = homeRoom;
}
@Override
public String toString() {
return name;
}
}
I am trying to group people by preferences, and I originally programmed this on greenfoot and it worked perfectly. However, I recently wanted to embed this in a project in intellij, with javafx. When I was testing, it system output null. Though I am also planning to loop a list of objects instead of adding each in the list - i tried that and it kept sending nulls.
[null, null, null]
[null, null, null]
[null, null]
I want to print something like
[person1, person3, person 6]
[person 5, person 2, person 4]
[person 7, person 8]
Why are you sorting the values and using AtomicInteger? Try it like this.
First, I added some names
int i = 1;
for (PeopleClass p : people) {
p.setName("Person" + i++);
}
Then I grouped on gender
List<List<PeopleClass>> groups = new ArrayList<>(people
.stream()
.collect(Collectors
.groupingBy(PeopleClass::getGender))
.values());
And printed them.
groups.forEach(System.out::println);
Here's the result
[Person3:n/a]
[Person2:female, Person4:female, Person5:female, Person6:female]
[Person1:male, Person8:male]
[Person7:trans]
Note: Your People class is missing some things like