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);
}
这是我的人民班
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;
}
}
我正在尝试按喜好对人员进行分组,而我最初是在greenfoot上编写此程序的,因此效果很好。但是,我最近想将其嵌入到具有javafx的intellij项目中。当我测试时,它的系统输出为null。尽管我还计划循环一个对象列表,而不是将每个对象添加到列表中-但我尝试了这一点,并一直发送空值。
[null, null, null]
[null, null, null]
[null, null]
我想打印类似的东西
[person1, person3, person 6]
[person 5, person 2, person 4]
[person 7, person 8]
首先,我添加了一些名称
int i = 1;
for (PeopleClass p : people) {
p.setName("Person" + i++);
}
然后我按性别分组
List<List<PeopleClass>> groups = new ArrayList<>(people .stream() .collect(Collectors .groupingBy(PeopleClass::getGender)) .values());
并打印出来。
groups.forEach(System.out::println);
这是结果
[Person3:n/a] [Person2:female, Person4:female, Person5:female, Person6:female] [Person1:male, Person8:male] [Person7:trans]
注意:您的People类缺少某些内容,例如