Question

---In the code, create add and delete a student by ID number when prompted

///////////////////////////////////////////////////////////////

import java.util.Scanner;

public class COurseCom666 {
    private String courseName;
    private String [] students = new String[1];
    private int numberOfStudents;

    public COurseCom66(String courseName) {
        this.courseName = courseName;
    }
    public String[] getStudents() {
        return students;
    }
    public int getNumberOfStudents() {
        return numberOfStudents;
    }
    public String getCourseName() {
        return courseName;
    }

    public void addStudent(String student) {
        // Automatically increases the array size
        if (numberOfStudents == students.length) {
            String[] a = new String[students.length + 1];
            for (int i = 0; i < numberOfStudents; i++) {
                a[i] = students[i];
            }
            students = a;
        }
        students[numberOfStudents] = student;
        numberOfStudents++;
    }
    public String[] addStudentByIndex(String student,int index){
        String [] a = new String[students.length+1];
        if (numberOfStudents == students.length){

            for (int i = 0; i < a.length;i++){
                if(i < index){
                    a[i] = students[i];
                }
                else if (i == index ){
                    a[i] = student;
                }
                else{
                    a[i] = students[i-1];
                }}
        }
        numberOfStudents++;
        return a;
    }
    public static void display(String[]students){
        System.out.println("========================");
        System.out.print("Now the New students Array is :\n");
        for(int i=0; i<students.length; i++)
        {
            System.out.println("Index: "+(i)+"--> "+ students[i]+" ");
        }
    }

    public String [] removeStudentByIndex(String [] a, int index){
        //find the index of student
        String [] b = new String[a.length-1];
        students = a;
        // int position = findStudent(student);
        for (int i = 0,k=0; i < a.length;i++){
            if (i == index){
                continue;
            }
            else{
                b[k++] = a[i];
            }
        }
        numberOfStudents--;

        return b;

    }
    private int findStudent(String student) {
        for (int i = 0; i < numberOfStudents; i++) {
            if (students[i].equals(student)) {
                return i;
            }
        }
        return -1;
    }
}

import java.util.Scanner;

public class d {

    public static void main(String[] args) {
        COurseCom666 com666 = new COurseCom666("com666");
        com666.addStudent("bishal");
        com666.addStudent("ana");
        com666.addStudent("ying");
        com666.addStudent("samuel");
        com666.addStudent("surai");

        int sum = 0;
        ////////create a new array String students1[] to hold all students/////////////////////
        String students1[] = com666.getStudents();

        sum += com666.getNumberOfStudents();
        Scanner scan = new Scanner(System.in);

        int choice;

        do {
            System.out.println("Welcome to College");
            System.out.println("1. View Student");
            System.out.println("2. Insert Student");
            System.out.println("3. Remove student");
            System.out.println("4. Exit");
            choice = scan.nextInt();
            if (choice == 1) {
                for (int i = 0; i < students1.length; i++) {
                    System.out.println("Index is: " + (i) + "---> " + students1[i]);
                }
                System.out.println("Number of students attending the Course is: " + sum);
            }
            else if (choice == 2) {
                System.out.println("Enter the name of student abd index: ");
                scan.nextLine();
                String student = scan.nextLine();
                students1 = com666.addStudentByIndex(student, 3);
                com666.display(students1);

                sum = com666.getNumberOfStudents();
                System.out.println("After student was added number is: " + sum);
            }
            else if (choice == 3) {
                System.out.println("Remove student by index");
                int index = scan.nextInt();
                students1 = com210.removeStudentByIndex(students1, index);
                com666.display(students1);
                sum = com666.getNumberOfStudents();
                System.out.println("After student drop number is: " + sum);
                System.out.println("Number of students attending the Course is: " + sum);
                System.out.println("----------------------------------");
            }
        }
        while (choice!= 4);
    }
}

Answer 1

Here you go:

import java.util.*;

public class Main {

private String courseName;

private String [] students = new String[1];

private int numberOfStudents;

public Main(String courseName) {

this.courseName = courseName;

}

public String[] getStudents() {

return students;

}

public int getNumberOfStudents() {

return numberOfStudents;

}

public String getCourseName() {

return courseName;

}

public void addStudent(String student) {

// Automatically increases the array size

if (numberOfStudents == students.length) {

String[] a = new String[students.length + 1];

for (int i = 0; i < numberOfStudents; i++) {

a[i] = students[i];

}

students = a;

}

students[numberOfStudents] = student;

numberOfStudents++;

}

public String[] addStudentByIndex(String student,int index){

String [] a = new String[students.length+1];

if (numberOfStudents == students.length){

for (int i = 0; i < a.length;i++){

if(i < index){

a[i] = students[i];

}

else if (i == index ){

a[i] = student;

}

else{

a[i] = students[i-1];

}}

}

numberOfStudents++;

return a;

}

public static void display(String[] students){

System.out.println("========================");

System.out.print("Now the New students Array is :\n");

for(int i=0; i<students.length; i++)

{

System.out.println("Index: "+(i)+"--> "+ students[i]+" ");

}

}

public String [] removeStudentByIndex(String [] a, int index){

//find the index of student

String [] b = new String[a.length-1];

students = a;

// int position = findStudent(student);

for (int i = 0,k=0; i < a.length;i++){

if (i == index){

continue;

}

else{

b[k++] = a[i];

}

}

numberOfStudents--;

return b;

}

private int findStudent(String student) {

for (int i = 0; i < numberOfStudents; i++) {

if (students[i].equals(student)) {

return i;

}

}

return -1;

}

public static void main(String[] args) {

Main com666 = new Main("com666");

com666.addStudent("bishal");

com666.addStudent("ana");

com666.addStudent("ying");

com666.addStudent("samuel");

com666.addStudent("surai");

int sum = 0;

////////create a new array String students1[] to hold all students/////////////////////

String students1[] = com666.getStudents();

sum += com666.getNumberOfStudents();

Scanner scan = new Scanner(System.in);

int choice;

do {

System.out.println("Welcome to College");

System.out.println("1. View Student");

System.out.println("2. Insert Student");

System.out.println("3. Remove student");

System.out.println("4. Exit");

choice = scan.nextInt();

if (choice == 1) {

for (int i = 0; i < students1.length; i++) {

System.out.println("Index is: " + (i) + "---> " + students1[i]);

}

System.out.println("Number of students attending the Course is: " + sum);

}

else if (choice == 2) {

System.out.println("Enter the name of student abd index: ");

scan.nextLine();

String student = scan.next();

int index = scan.nextInt();

students1 = com666.addStudentByIndex(student, index);

com666.display(students1);

sum = com666.getNumberOfStudents();

System.out.println("After student was added number is: " + sum);

}

else if (choice == 3) {

System.out.println("Remove student by index");

int index = scan.nextInt();

students1 = com666.removeStudentByIndex(students1, index);

com666.display(students1);

sum = com666.getNumberOfStudents();

System.out.println("After student drop number is: " + sum);

System.out.println("Number of students attending the Course is: " + sum);

System.out.println("----------------------------------");

}

}

while (choice!= 4);

}

}

Check the image below for code structure and output:

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