Java compiler: https://www.onlinegdb.com/

Bài 1:

Để quản lý các hộ dân cư trong một khu phố, người ta cần các thông tin sau: Số thành viên trong gia đình, Số nhà, thông tin mỗi cá nhân trong gia đinh. Với mỗi cá nhân, người ta quản lý các thông tin sau: Họ tên, Tuổi, Nghề nghiệp, Số chứng minh nhân dân (duy nhất cho mỗi người).

import java.util.Scanner;

class Person {
    private String fullName;
    private int age;
    private String occupation;
    private String idNumber;

    public Person(String fullName, int age, String occupation, String idNumber) {
        this.fullName = fullName;
        this.age = age;
        this.occupation = occupation;
        this.idNumber = idNumber;
    }

    public void displayInfo() {
        System.out.println("- Full Name: " + fullName);
        System.out.println("- Age: " + age);
        System.out.println("- Occupation: " + occupation);
        System.out.println("- ID Number: " + idNumber);
    }
}


class House {
    private int numberOfHouse;
    private int numberOfResidentsPerHouse;
    private String address;
    private Person[] persons;

    public House(int numberOfHouse, int numberOfResidentsPerHouse, String address) {
        this.numberOfHouse = numberOfHouse;
        this.numberOfResidentsPerHouse = numberOfResidentsPerHouse;
        this.address = address;
        persons = new Person[numberOfResidentsPerHouse];
    }
    
    public void enterResidentsPerHouseInfo(int numberOfResidentsPerHouse) {
        Scanner sc = new Scanner(System.in);
        for (int i = 0; i < numberOfResidentsPerHouse; i++) {
            System.out.println("Enter information for person " + (i + 1));
            System.out.print("- Full Name: ");
            String fullName = sc.nextLine();
            System.out.print("- Age: ");
            int age = sc.nextInt();
            sc.nextLine();
            System.out.print("- Occupation: ");
            String occupation = sc.nextLine();
            System.out.print("- ID Number: ");
            String idNumber = sc.nextLine();
            persons[i] = new Person(fullName, age, occupation, idNumber);
        }
    }

    public void displayHouseInfo() {
        System.out.println("Information for household " + (numberOfHouse + 1));
        System.out.println("+ Address: " + address);
        System.out.println("+ Number of residents in house: " + numberOfResidentsPerHouse);
        for (int i = 0; i < numberOfResidentsPerHouse; i++) {
            System.out.println("Person " + (i + 1) + ":");
            persons[i].displayInfo();
        }
    }
}

class Neighborhood {
    private int numberOfHouses;
    private House[] houses;

    public Neighborhood(int numberOfHouses) {
        this.numberOfHouses = numberOfHouses;
        houses = new House[numberOfHouses];
    }

    public void enterHouseInfo(int numberOfHouses) {
        Scanner sc = new Scanner(System.in);
        for (int i = 0; i < numberOfHouses; i++) {
            System.out.println("Enter information for household " + (i + 1));
            System.out.print("Enter the number of residents in house "+ (i + 1) +": ");
            int numberOfResidentsPerHouse = sc.nextInt();
            sc.nextLine();
            System.out.print("Enter the address: ");
            String address = sc.nextLine();
            houses[i] = new House(i, numberOfResidentsPerHouse, address);
            houses[i].enterResidentsPerHouseInfo(numberOfResidentsPerHouse);
        }
    }

    public void displayNeighborhoodInfo() {
        for (int i = 0; i < numberOfHouses; i++) {
            houses[i].displayHouseInfo();
        }
    }
}

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter the number of houses in the neighborhood: ");
        int numberOfHouses = sc.nextInt();
        System.out.println("-------------------------------------------");

        Neighborhood neighborhood = new Neighborhood(numberOfHouses);
        neighborhood.enterHouseInfo(numberOfHouses);

        System.out.println("--------------------------------------------");
        System.out.println("| List of information for the neighborhood |");
        System.out.println("--------------------------------------------");
        neighborhood.displayNeighborhoodInfo();
    }
}

Bài 2:

Để quản lý hồ sơ học sinh của trường THPT nhà trường cần các thông tin sau: Lớp, và các thông tin về cá nhân của mỗi học sinh. Mỗi học sinh có các thông tin sau: Họ tên, tuổi, quê quán. Cài đặt chương trình có các chức năng sau:

import java.util.ArrayList;
import java.util.Scanner;

class Student {
    private String fullName;
    private int age;
    private String hometown;

    public Student(String fullName, int age, String hometown) {
        this.fullName = fullName;
        this.age = age;
        this.hometown = hometown;
    }

    public int getAge() {
        return age;
    }

    public String getHometown() {
        return hometown;
    }

    public String toString() {
        return "- Full Name: " + fullName + ", Age: " + age + ", Hometown: " + hometown;
    }
}

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        ArrayList<Student> studentList = new ArrayList<Student>();

        System.out.print("Enter the number of students: ");
        int n = scanner.nextInt();
        scanner.nextLine(); 

        for (int i = 0; i < n; i++) {
            System.out.println("Enter information for student " + (i + 1) + ":");
            System.out.print("- Full Name: ");
            String fullName = scanner.nextLine();
            System.out.print("- Age: ");
            int age = scanner.nextInt();
            scanner.nextLine(); 
            System.out.print("- Hometown: ");
            String hometown = scanner.nextLine();

            Student student = new Student(fullName, age, hometown);
            studentList.add(student);
        }
        System.out.println("-----------------------------------------");
        System.out.println("| List of students who are 20 years old |");
        System.out.println("-----------------------------------------");
        for (Student student : studentList) {
            if (student.getAge() == 20) {
                System.out.println(student);
            }
        }

        int numberOfStudents23YearsOldHanoi = 0;
        for (Student student : studentList) {
            if (student.getAge() == 23 && student.getHometown().equalsIgnoreCase("Hanoi")) {
                numberOfStudents23YearsOldHanoi++;
            }
        }
        System.out.println("\n--------------------------------------------------------------");
        System.out.println("Number of students who are 23 years old and come from Hanoi: " + numberOfStudents23YearsOldHanoi);
    }
}