Untitled

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

class Student {
    private int id;
    private String name;
    private String gender;
    private int age;

    public Student (int id, String name, String gender, int age) {
        this.id = id;
        this.name = name;
        this.gender = gender;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public int getId() {
        return id;
    }

    public String getGender() {
        return gender;
    }

    public int getAge() {
        return age;
    }
}

class StudentDTO {
    private int id;
    private String name;
    private String gender;
    private int age;

    public StudentDTO (int id, String name, String gender, int age) {
        this.id = id;
        this.name = name;
        this.gender = gender;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public int getId() {
        return id;
    }

    public String getGender() {
        return gender;
    }

    public int getAge() {
        return age;
    }
}
public class Main {
    public static void main(String[] args) {

        List<Student> list = Arrays.asList(new Student(1,"A","male",26), new Student(2,"B","female",26), new Student(3,"C","male",16), new Student(4,"D","male",26));

        List<Student> maleList = list.stream().filter(student -> student.getGender().equals("male")).collect(Collectors.toList());

        long count = list.stream().filter(student -> student.getAge() > 20).count();

        List<StudentDTO> studentDTOList = list.stream()
                .map(s -> new StudentDTO(s.getId(), s.getName(), s.getGender(), s.getAge()))
                .collect(Collectors.toList());


    }
}