Spring Boot - Fundamentals - Guided Exercise - CampusBoard – Backend Brains for a Web App #186

akash-coded · 2025-06-05T04:33:03Z

akash-coded
Jun 5, 2025
Maintainer

🧪 Guided Exercise: CampusBoard – Backend Brains for a Web App

🎯 Scenario

You’re building CampusBoard, an internal backend system for a university portal. While the frontend isn’t ready yet, your job is to:

Build backend logic layers (model → service → CLI interface)
Simulate incoming user actions (like register, enroll, list)
Store and retrieve data using Java collections
Prepare it all inside a Spring Boot CLI app (no @RestController yet)

This will act as the internal engine for future APIs.

📦 Features to Simulate (CLI Only)

Register new students
List all students
Enroll student to a course
Show course-wise enrolled students
Show enrollment summary (total students per course)
Remove student

🛠 Project Setup

Step 1: Go to https://start.spring.io

Generate a project with:

Group: com.campusboard
Artifact: campusboard
Name: campusboard
Dependencies: Spring Boot DevTools (optional)

Import into Eclipse.

🔧 Implementation Steps

✅ Step 2: Create Model Classes

📄 `Student.java`

package com.campusboard.model;
public class Student {

private int id;

private String name;

private String email;
public Student(int id, String name, String email) {
    this.id = id;
    this.name = name;
    this.email = email;
}

// TODO: Add Getters, Setters, toString()

}

📄 `Course.java`

package com.campusboard.model;
public class Course {

private String code;

private String title;
public Course(String code, String title) {
    this.code = code;
    this.title = title;
}

// TODO: Getters, Setters, toString()

}

✅ Step 3: Create Services

📄 `StudentService.java`

package com.campusboard.service;
import com.campusboard.model.Student;

import org.springframework.stereotype.Service;
import java.util.*;
@Service

public class StudentService {

private List<Student> studentList = new ArrayList<>();
public void registerStudent(Student student) {
    studentList.add(student);
    System.out.println("✅ Student registered.");
}

public List&lt;Student&gt; getAllStudents() {
    return studentList;
}

public Student getStudentById(int id) {
    return studentList.stream()
            .filter(s -&gt; s.getId() == id)
            .findFirst()
            .orElse(null);
}

public void removeStudentById(int id) {
    studentList.removeIf(s -&gt; s.getId() == id);
    System.out.println("🗑️ Student removed.");
}

}

📄 `CourseService.java`

package com.campusboard.service;
import com.campusboard.model.Course;

import org.springframework.stereotype.Service;
import java.util.*;
@Service

public class CourseService {

private Map<String, Course> courseMap = new HashMap<>();
public void addCourse(Course course) {
    courseMap.put(course.getCode(), course);
    System.out.println("📚 Course added.");
}

public Course getCourseByCode(String code) {
    return courseMap.get(code);
}

public Collection&lt;Course&gt; getAllCourses() {
    return courseMap.values();
}

}

📄 `EnrollmentService.java`

package com.campusboard.service;
import com.campusboard.model.Student;

import com.campusboard.model.Course;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;
import java.util.*;
@Service

public class EnrollmentService {
private Map&lt;String, List&lt;Student&gt;&gt; enrollmentMap = new HashMap&lt;&gt;();

public void enroll(Student student, Course course) {
    enrollmentMap
        .computeIfAbsent(course.getCode(), k -&gt; new ArrayList&lt;&gt;())
        .add(student);

    System.out.println("✅ Enrolled " + student.getName() + " to " + course.getTitle());
}

public List&lt;Student&gt; getStudentsByCourse(String courseCode) {
    return enrollmentMap.getOrDefault(courseCode, Collections.emptyList());
}

public void showEnrollmentSummary() {
    System.out.println("📊 Enrollment Summary:");
    enrollmentMap.forEach((code, students) -&gt;
        System.out.println(code + ": " + students.size() + " students enrolled.")
    );
}

}

✅ Step 4: Main CLI App – `CampusBoardApp.java`

package com.campusboard;
import com.campusboard.model.;

import com.campusboard.service.;
import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.*;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import java.util.*;
@SpringBootApplication

public class CampusBoardApp implements CommandLineRunner {
@Autowired
StudentService studentService;

@Autowired
CourseService courseService;

@Autowired
EnrollmentService enrollmentService;

public static void main(String[] args) {
    SpringApplication.run(CampusBoardApp.class, args);
}

@Override
public void run(String... args) {
    Scanner sc = new Scanner(System.in);
    System.out.println("🎓 Welcome to CampusBoard CLI");
    while (true) {
        System.out.print("🔹 Command: ");
        String input = sc.nextLine().trim().toLowerCase();

        switch (input) {
            case "register":
                System.out.print("Enter ID: ");
                int id = Integer.parseInt(sc.nextLine());
                System.out.print("Enter Name: ");
                String name = sc.nextLine();
                System.out.print("Enter Email: ");
                String email = sc.nextLine();
                studentService.registerStudent(new Student(id, name, email));
                break;

            case "list":
                studentService.getAllStudents().forEach(System.out::println);
                break;

            case "addcourse":
                System.out.print("Enter Course Code: ");
                String code = sc.nextLine();
                System.out.print("Enter Course Title: ");
                String title = sc.nextLine();
                courseService.addCourse(new Course(code, title));
                break;

            case "enroll":
                System.out.print("Student ID: ");
                int sid = Integer.parseInt(sc.nextLine());
                System.out.print("Course Code: ");
                String ccode = sc.nextLine();
                Student student = studentService.getStudentById(sid);
                Course course = courseService.getCourseByCode(ccode);
                if (student != null &amp;&amp; course != null) {
                    enrollmentService.enroll(student, course);
                } else {
                    System.out.println("❌ Student or course not found.");
                }
                break;

            case "showcourse":
                System.out.print("Course Code: ");
                String showCode = sc.nextLine();
                enrollmentService.getStudentsByCourse(showCode)
                                 .forEach(System.out::println);
                break;

            case "summary":
                enrollmentService.showEnrollmentSummary();
                break;

            case "exit":
                System.out.println("👋 Exiting CampusBoard. Bye!");
                return;

            default:
                System.out.println("❓ Unknown command. Try register, list, enroll, showcourse, summary, exit");
        }
    }
}

}

🧪 Guided Practice Tasks

✅ Add removeCourse(String code) in CourseService
✅ Prevent duplicate student IDs
✅ Prevent enrolling to non-existent course
✅ Add confirmation before deleting student
✅ Count total students overall
✅ Add updateEmail(int id, String newEmail) method
✅ Add simple login (student ID + password map)

📘 What They'll Internalize

Concept	Reinforced Through
Java Classes & OOP	Student, Course, Service layers
Dependency Injection	@Autowired services in CommandLineRunner
Spring Boot project structure	model → service → main app
CLI project design	Simulating endpoints without web
Collections API	List, Map, Set usage
Clean coding & reuse	Service separation, no duplicate logic

Let me know if you want:

.docx or .pdf printable version
Starter repo / ZIP for students
Auto-testing script to validate output of commands

Got it. Since you’ve only introduced:

Web development basics
Frontend vs Backend
Web app vs API
HTTP concepts (GET, POST, etc.)
Demoed public APIs like reqres.in
Generated a Spring Boot project from [start.spring.io](https://start.spring.io) and ran it as a CLI

You haven’t yet taught them how to build APIs using @RestController.

So let’s design a compelling, creative, multi-part CLI-based Spring Boot exercise that:

Uses only Spring Boot CLI app structure
Helps them reinforce OOP, Java basics, services, components, collections, dependency injection
Simulates how real-world backend apps work internally
Sets them up mentally to later expose these via APIs

🧪 Guided Exercise: CampusBoard – Backend Brains for a Web App

🎯 Scenario

You’re building CampusBoard, an internal backend system for a university portal. While the frontend isn’t ready yet, your job is to:

Build backend logic layers (model → service → CLI interface)
Simulate incoming user actions (like register, enroll, list)
Store and retrieve data using Java collections
Prepare it all inside a Spring Boot CLI app (no @RestController yet)

This will act as the internal engine for future APIs.

📦 Features to Simulate (CLI Only)

Register new students
List all students
Enroll student to a course
Show course-wise enrolled students
Show enrollment summary (total students per course)
Remove student

🛠 Project Setup

Step 1: Go to https://start.spring.io/

Generate a project with:

Group: com.campusboard
Artifact: campusboard
Name: campusboard
Dependencies: Spring Boot DevTools (optional)

Import into Eclipse.

🔧 Implementation Steps

✅ Step 2: Create Model Classes

📄 `Student.java`

package com.campusboard.model;

public class Student {
    private int id;
    private String name;
    private String email;

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

    // TODO: Add Getters, Setters, toString()
}

📄 `Course.java`

package com.campusboard.model;

public class Course {
    private String code;
    private String title;

    public Course(String code, String title) {
        this.code = code;
        this.title = title;
    }

    // TODO: Getters, Setters, toString()
}

✅ Step 3: Create Services

📄 `StudentService.java`

package com.campusboard.service;

import com.campusboard.model.Student;
import org.springframework.stereotype.Service;

import java.util.*;

@Service
public class StudentService {
    private List<Student> studentList = new ArrayList<>();

    public void registerStudent(Student student) {
        studentList.add(student);
        System.out.println("✅ Student registered.");
    }

    public List<Student> getAllStudents() {
        return studentList;
    }

    public Student getStudentById(int id) {
        return studentList.stream()
                .filter(s -> s.getId() == id)
                .findFirst()
                .orElse(null);
    }

    public void removeStudentById(int id) {
        studentList.removeIf(s -> s.getId() == id);
        System.out.println("🗑️ Student removed.");
    }
}

📄 `CourseService.java`

package com.campusboard.service;

import com.campusboard.model.Course;
import org.springframework.stereotype.Service;

import java.util.*;

@Service
public class CourseService {
    private Map<String, Course> courseMap = new HashMap<>();

    public void addCourse(Course course) {
        courseMap.put(course.getCode(), course);
        System.out.println("📚 Course added.");
    }

    public Course getCourseByCode(String code) {
        return courseMap.get(code);
    }

    public Collection<Course> getAllCourses() {
        return courseMap.values();
    }
}

📄 `EnrollmentService.java`

package com.campusboard.service;

import com.campusboard.model.Student;
import com.campusboard.model.Course;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.*;

@Service
public class EnrollmentService {

    private Map<String, List<Student>> enrollmentMap = new HashMap<>();

    public void enroll(Student student, Course course) {
        enrollmentMap
            .computeIfAbsent(course.getCode(), k -> new ArrayList<>())
            .add(student);

        System.out.println("✅ Enrolled " + student.getName() + " to " + course.getTitle());
    }

    public List<Student> getStudentsByCourse(String courseCode) {
        return enrollmentMap.getOrDefault(courseCode, Collections.emptyList());
    }

    public void showEnrollmentSummary() {
        System.out.println("📊 Enrollment Summary:");
        enrollmentMap.forEach((code, students) ->
            System.out.println(code + ": " + students.size() + " students enrolled.")
        );
    }
}

✅ Step 4: Main CLI App – `CampusBoardApp.java`

package com.campusboard;

import com.campusboard.model.*;
import com.campusboard.service.*;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.*;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import java.util.*;

@SpringBootApplication
public class CampusBoardApp implements CommandLineRunner {

    @Autowired
    StudentService studentService;

    @Autowired
    CourseService courseService;

    @Autowired
    EnrollmentService enrollmentService;

    public static void main(String[] args) {
        SpringApplication.run(CampusBoardApp.class, args);
    }

    @Override
    public void run(String... args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("🎓 Welcome to CampusBoard CLI");
        while (true) {
            System.out.print("🔹 Command: ");
            String input = sc.nextLine().trim().toLowerCase();

            switch (input) {
                case "register":
                    System.out.print("Enter ID: ");
                    int id = Integer.parseInt(sc.nextLine());
                    System.out.print("Enter Name: ");
                    String name = sc.nextLine();
                    System.out.print("Enter Email: ");
                    String email = sc.nextLine();
                    studentService.registerStudent(new Student(id, name, email));
                    break;

                case "list":
                    studentService.getAllStudents().forEach(System.out::println);
                    break;

                case "addcourse":
                    System.out.print("Enter Course Code: ");
                    String code = sc.nextLine();
                    System.out.print("Enter Course Title: ");
                    String title = sc.nextLine();
                    courseService.addCourse(new Course(code, title));
                    break;

                case "enroll":
                    System.out.print("Student ID: ");
                    int sid = Integer.parseInt(sc.nextLine());
                    System.out.print("Course Code: ");
                    String ccode = sc.nextLine();
                    Student student = studentService.getStudentById(sid);
                    Course course = courseService.getCourseByCode(ccode);
                    if (student != null && course != null) {
                        enrollmentService.enroll(student, course);
                    } else {
                        System.out.println("❌ Student or course not found.");
                    }
                    break;

                case "showcourse":
                    System.out.print("Course Code: ");
                    String showCode = sc.nextLine();
                    enrollmentService.getStudentsByCourse(showCode)
                                     .forEach(System.out::println);
                    break;

                case "summary":
                    enrollmentService.showEnrollmentSummary();
                    break;

                case "exit":
                    System.out.println("👋 Exiting CampusBoard. Bye!");
                    return;

                default:
                    System.out.println("❓ Unknown command. Try register, list, enroll, showcourse, summary, exit");
            }
        }
    }
}

🧪 Guided Practice Tasks

✅ Add removeCourse(String code) in CourseService
✅ Prevent duplicate student IDs
✅ Prevent enrolling to non-existent course
✅ Add confirmation before deleting student
✅ Count total students overall
✅ Add updateEmail(int id, String newEmail) method
✅ Add simple login (student ID + password map)

📘 What They'll Internalize

Concept	Reinforced Through
Java Classes & OOP	`Student`, `Course`, `Service` layers
Dependency Injection	`@Autowired` services in `CommandLineRunner`
Spring Boot project structure	model → service → main app
CLI project design	Simulating endpoints without web
Collections API	`List`, `Map`, `Set` usage
Clean coding & reuse	Service separation, no duplicate logic

Sdey0907 · 2025-06-05T13:37:49Z

Sdey0907
Jun 5, 2025

**_

Task - Campusboard_Backend Web Application _Completed_Sayan Dey

_**

Campusboard_BackendWebApplication.zip

0 replies

prasetha21-max · 2025-06-05T15:58:17Z

prasetha21-max
Jun 5, 2025

campusboard.zip

0 replies

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Spring Boot - Fundamentals - Guided Exercise - CampusBoard – Backend Brains for a Web App #186

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Spring Boot - Fundamentals - Guided Exercise - CampusBoard – Backend Brains for a Web App #186

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akash-coded Jun 5, 2025 Maintainer

🧪 Guided Exercise: CampusBoard – Backend Brains for a Web App

🎯 Scenario

📦 Features to Simulate (CLI Only)

🛠 Project Setup

Step 1: Go to https://start.spring.io

🔧 Implementation Steps

✅ Step 2: Create Model Classes

📄 Student.java

📄 Course.java

✅ Step 3: Create Services

📄 StudentService.java

📄 CourseService.java

📄 EnrollmentService.java

✅ Step 4: Main CLI App – CampusBoardApp.java

🧪 Guided Practice Tasks

📘 What They'll Internalize

🧪 Guided Exercise: CampusBoard – Backend Brains for a Web App

🎯 Scenario

📦 Features to Simulate (CLI Only)

🛠 Project Setup

Step 1: Go to https://start.spring.io/

🔧 Implementation Steps

✅ Step 2: Create Model Classes

📄 Student.java

📄 Course.java

✅ Step 3: Create Services

📄 StudentService.java

📄 CourseService.java

📄 EnrollmentService.java

✅ Step 4: Main CLI App – CampusBoardApp.java

🧪 Guided Practice Tasks

📘 What They'll Internalize

Replies: 2 comments

Uh oh!

Sdey0907 Jun 5, 2025

**_

Uh oh!

prasetha21-max Jun 5, 2025

akash-coded
Jun 5, 2025
Maintainer

📄 `Student.java`

📄 `Course.java`

📄 `StudentService.java`

📄 `CourseService.java`

📄 `EnrollmentService.java`

✅ Step 4: Main CLI App – `CampusBoardApp.java`

📄 `Student.java`

📄 `Course.java`

📄 `StudentService.java`

📄 `CourseService.java`

📄 `EnrollmentService.java`

✅ Step 4: Main CLI App – `CampusBoardApp.java`

Sdey0907
Jun 5, 2025

prasetha21-max
Jun 5, 2025