How to filter the same values ​​​​and filter different values ​​​​in a list in java

The code is as follows:

public class People {
    private String id;
    private String somethingElse;

    public People() {
    }

    public People(String id, String somethingElse) {
        this.id = id;
        this.somethingElse = somethingElse;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getSomethingElse() {
        return somethingElse;
    }

    public void setSomethingElse(String somethingElse) {
        this.somethingElse = somethingElse;
    }

    @Override
    public String toString() {
        return "People{" +
                "id='" + id + '\'' +
                ", somethingElse='" + somethingElse + '\'' +
                '}';
    }
}

people entity class and student entity class
People class

student
public class Student {
    private String id;
    private String idCard;
    private String somethingElse;

    public Student() {
    }

    public Student(String id, String idCard, String somethingElse) {
        this.id = id;
        this.idCard = idCard;
        this.somethingElse = somethingElse;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getIdCard() {
        return idCard;
    }

    public void setIdCard(String idCard) {
        this.idCard = idCard;
    }

    public String getSomethingElse() {
        return somethingElse;
    }

    public void setSomethingElse(String somethingElse) {
        this.somethingElse = somethingElse;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id='" + id + '\'' +
                ", idCard='" + idCard + '\'' +
                ", somethingElse='" + somethingElse + '\'' +
                '}';
    }
}

Test class

public static void main(String[] args) throws Exception{
//初始化数据
        List<Student> studentList = new ArrayList(){{
               add(new Student("1", "11", "111")) ;
               add(new Student("2", "22", "222"));
               add(new Student("3", "33", "333"));
        }};
        List<People> peopleList = new ArrayList(){
            {
                add(new People("11", "111"));
                add(new People("222", "222"));
                add(new People("33", "333"));
        }};
        //获取相同字段内容，转化为set
        Set<String> ids = peopleList
                .stream()
                .map(People::getId)
                .collect(Collectors.toSet());//过滤重复内容
        List<Student> result = studentList
                .stream()
                .filter(e -> ids.contains(e.getIdCard()))
                .collect(Collectors.toList());
        System.out.println(result);
         //获取相同字段内容，转化为set
        Set<String> ids = peopleList
                .stream()
                .map(People::getId)
                .collect(Collectors.toSet());//过滤重复内容
        List<Student> result = studentList
                .stream()
                .filter(e -> !ids.contains(e.getIdCard()))
                .collect(Collectors.toList());
        System.out.println(result);
}

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