System Requirements

Build a console-based student information management system supporting add, delete, and query operations for student records, with the following specifications:

1. Define a Student class to store student data, with all attributes set to private access. Required attributes: student ID, full name, gender.
2. Implement core operations: add new student, delete existing student, query student by ID.
3. Store all student objects in a fixed-size array with a maximum capacity of 30.

After startup, the program displays a menu for user operation selection:

1. Add student
2. Delete student
3. Query student
4. Exit

• When adding: prompt user to input student ID, name, gender sequetnially, wrap into a Student object and store in the array.
• When deleting: require input of student ID, remove the matching student from the array if it exists.
• When querying: require input of student ID, output the full student information if found.

Student Clas

package io.example.studentmanager;

public class Student {
    private int studentId;
    private String fullName;
    private String gender;

    public int getStudentId() {
        return studentId;
    }

    public void setStudentId(int studentId) {
        this.studentId = studentId;
    }

    public String getFullName() {
        return fullName;
    }

    public void setFullName(String fullName) {
        this.fullName = fullName;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    @Override
    public String toString() {
        return "Student [ID: " + studentId + ", Name: " + fullName + ", Gender: " + gender + "]";
    }
}

Student Management Core Class

package io.example.studentmanager;

import java.util.Scanner;

public class StudentManager {
    private static Scanner input = new Scanner(System.in);
    private final int MAX_CAPACITY = 30;
    private Student[] studentRecords = new Student[MAX_CAPACITY];
    private int currentRecordCount = 0;

    public void showMainMenu() {
        mainLoop: while (true) {
            System.out.println("Please select an operation: 1. Add Student  2. Delete Student  3. Query Student  4. Exit");
            int selection = input.nextInt();
            switch (selection) {
                case 1 -> addNewStudent();
                case 2 -> deleteStudentById();
                case 3 -> queryStudentById();
                case 4 -> { break mainLoop; }
            }
        }
    }

    private void addNewStudent() {
        if (currentRecordCount == MAX_CAPACITY) {
            System.out.println("System is full, cannot add more students.");
            return;
        }

        Student newStudent = new Student();
        System.out.println("Enter student ID:");
        newStudent.setStudentId(input.nextInt());
        System.out.println("Enter student name:");
        newStudent.setFullName(input.next());
        System.out.println("Enter student gender:");
        newStudent.setGender(input.next());

        studentRecords[currentRecordCount++] = newStudent;
        System.out.println("Student added successfully.");
    }

    private void deleteStudentById() {
        System.out.println("Enter the ID of the student to delete:");
        int targetId = input.nextInt();
        int foundIndex = -1;

        for (int i = 0; i < currentRecordCount; i++) {
            if (studentRecords[i].getStudentId() == targetId) {
                foundIndex = i;
                // Shift all subsequent records forward to fill the gap
                for (int j = foundIndex; j < currentRecordCount - 1; j++) {
                    studentRecords[j] = studentRecords[j + 1];
                }
                currentRecordCount--;
                break;
            }
        }

        if (foundIndex == -1) {
            System.out.println("No student matching the provided ID was found.");
        } else {
            System.out.println("Student deleted successfully.");
        }
    }

    private void queryStudentById() {
        System.out.println("Enter the student ID to query:");
        int targetId = input.nextInt();

        // Only traverse existing records to avoid null pointer exceptions
        for (int i = 0; i < currentRecordCount; i++) {
            if (studentRecords[i].getStudentId() == targetId) {
                System.out.println(studentRecords[i]);
                return;
            }
        }

        System.out.println("No student matching the provided ID was found.");
    }
}

Program Entry Point

package io.example.studentmanager;

public class Main {
    public static void main(String[] args) {
        StudentManager manager = new StudentManager();
        manager.showMainMenu();
    }
}