컬렉션 복사

void main() {
  dynamic list = [1, 2, 3, 4];

  list.add(5);

  dynamic newList = list;

  newList.add(6);

  print(newList); // 출력: [1, 2, 3, 4, 5, 6]
  print(list);    // 출력: [1, 2, 3, 4, 5, 6]

  print(list.hashCode);
  print(newList.hashCode);
}

package ex14.example1;

import java.util.ArrayList;
import java.util.List;

public class CopyEx01 {
    public static void main(String[] args) {
        List<Integer> list = new ArrayList<>();
        list.add(1);
        list.add(2);
        list.add(3);
        list.add(4);

        // 컬렉션 복사
        List<Integer> newList = new ArrayList<>(list);
        System.out.println(list.hashCode());
        System.out.println(newList.hashCode());

        newList.add(5);

        System.out.println(list.hashCode());
        System.out.println(newList.hashCode());

          // 이전
//        var newList = new ArrayList<>();
//        for (int i = 0; i < list.size(); i++) {
//            newList.add(list.get(i));
//        }
    }
}

package ex14.example1;

class User {
    private int id;
    private String name;
    private String tel;

    2) public User(User user) {
        this.id = user.getId();
        this.name = user.getName();
        this.tel = user.getTel();
    }

    public User(int id, String name, String tel) {
        this.id = id;
        this.name = name;
        this.tel = tel;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", tel='" + tel + '\'' +
                '}';
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getTel() {
        return tel;
    }
}

public class CopyEx04 {
    public static void main(String[] args) {
        User u1 = new User(1, "ssar", "0102222");

        // 1. 통째로 복사
				1) User u2 = new User(u1.getId(), u1.getName(), u1.getTel());
        2) User u2 = new User(u1);

        // 2. 부분변경 복사
        User u3 = new User(u1.getId(), u1.getName(), "0103333");
    }
}

package ex14.example1;

import java.time.LocalDateTime;

// Data Transfer Object
class JoinDTO {
    private String username; // ssar
    private String password;
    private String email;

    public JoinDTO(String username, String password, String email) {
        this.username = username;
        this.password = password;
        this.email = email;
    }

    public String getUsername() {
        return username;
    }

    public String getPassword() {
        return password;
    }

    public String getEmail() {
        return email;
    }
}

class Member {
    private int no;
    private String username;
    private String password;
    private String email;
    private LocalDateTime createdAt;

    public Member(int no, JoinDTO dto) {
        this.no = no;
        this.username = dto.getUsername();
        this.password = dto.getPassword();
        this.email = dto.getEmail();
        this.createdAt = LocalDateTime.now();
    }
}


public class CopyEx05 {
    public static void main(String[] args) {
        JoinDTO d1 = new JoinDTO("ssar", "1234", "ssar@nate.com");
        JoinDTO d2 = new JoinDTO("cos", "1234", "cos@nate.com");

        Member m1 = new Member(1, d1);
        Member m2 = new Member(2, d2);

        // 이전
//        LocalDateTime now = LocalDateTime.now();
//        System.out.println(now);
    }
}