tasks.psupel

// 1st task

public class Main01 {

    public static void createPicture(int n) {

        if (n > 0) {

            int i;
            int j;
            int min;

            for (i = 1; i <= n; i++) {

                for (j = 1; j <= n; j++) {

                    min = i < j ? i : j;

                    System.out.print(n - min + 1);
                }

                for (j = n - 1; j >= 1; j--) {

                    min = i < j ? i : j;

                    System.out.print(n - min + 1);
                }

                System.out.println();
            }

            for (i = n - 1; i >= 1; i--) {

                for (j = 1; j <= n; j++) {

                    min = i < j ? i : j;

                    System.out.print(n - min + 1);
                }
                for (j = n - 1; j >= 1; j--) {

                    min = i < j ? i : j;

                    System.out.print(n - min + 1);
                }
                System.out.println();
            }
        } else {

            throw new IllegalArgumentException("n must be positive");
        }
    }

    public static void main(String[] args) {

        createPicture(4);
    }
}

// 2nd task

import java.util.ArrayList;

public class Main02 {

    public static ArrayList<Integer> findNPerfectNumbers(int n) {

        int sum;
        ArrayList<Integer> resultList = new ArrayList<>();

        for (int i = 6; resultList.size() < n; i++) {

            ArrayList<Integer> factorList = new ArrayList<>();

            for (int j = 1; j <= i / 2; j++) {

                if (i % j == 0) {
                    factorList.add(j);
                }
            }

            sum = 0;

            for (Integer f : factorList) {
                sum += f;
            }

            if (sum == i) {

                resultList.add(i);
            }

        }
         return resultList;
    }

    public static void main(String[] args) {

        System.out.println(findNPerfectNumbers(4));
    }
}

// 3rd task - Dto Class (Lombok dependency)

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;

@Data
@ToString
@NoArgsConstructor
@AllArgsConstructor
public class PostDto {

    private long userId;

    private long id;

    private String title;

    private String body;
}

// 3rd task (Jackson dependency)

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.util.List;

public class Main03 {

    private static final String POSTS_API_URL = "https://jsonplaceholder.typicode.com/posts";

    public static void getPosts() throws IOException, InterruptedException {

        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
                .GET()
                .header("accept", "application/json")
                .uri(URI.create(POSTS_API_URL))
                .build();

        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());

        ObjectMapper mapper = new ObjectMapper();

        List<PostDto> posts = mapper.readValue(response.body(), new TypeReference<>() {
        });

        posts.forEach(System.out::println);
    }


    public static void main(String[] args) throws IOException, InterruptedException {

        getPosts();
    }
}