Question

In this create a code that will drop a student by ID number

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

import java.util.Scanner;

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

    public COurseCom666(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("jake");
        com666.addStudent("becky");
        com666.addStudent("mai");
        com666.addStudent("sam");
        com666.addStudent("paul");

        int sum = 0;
       
        String students1[] = com210.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 a 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 and 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 a 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);
    }
}

Answer 1

Program :-

import java.util.Scanner;

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

public COurseCom666(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];
  
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];
}
}
students = a;
numberOfStudents++;
return a;
}
public 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 class Demo {

public static void main(String[] args) {
COurseCom666 com666 = new COurseCom666("com666");
com666.addStudent("jake");
com666.addStudent("becky");
com666.addStudent("mai");
com666.addStudent("sam");
com666.addStudent("paul");

int sum = 0;

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 a 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 and index: ");
scan.nextLine();
String student = scan.nextLine();
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 a 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);
  
scan.close();
}
}