how do I rewrite this using ArrayList public class Course C

how do I rewrite this using ArrayList

public class Course {

//Create Students
public String courseName;
public String []students = new String [100];
private int NumberOfStudents;

//Add Course

public Course(String courseName) {
this.courseName = courseName;  
}
public void addStudent(String student){
students[NumberOfStudents] = student;
NumberOfStudents++;
}

//Return Student
public String[]getStudents(){
   return students;
}
public int getNumberOfStudents(){
   return NumberOfStudents;
}
public String getcoursName(){
   return courseName;
}
public void dropStudent(String student){
   for (int i = 0; i < NumberOfStudents; i++) {
   if (students[i].equals(student)) {
   // Move students[i + 1] to students[i], etc.
   for (int k = i + 1; k < NumberOfStudents; k++) {
   students[k - 1] = students[k];
}
   NumberOfStudents--;
   break;
   }
   }
}
//increase Array when student are added by 1
public void addArray() {
   if (NumberOfStudents >= students.length) {
String old [] = new String[students.length * 1];
   System.arraycopy(students, 0, old, 0, students.length);
students = old;
}
}//end increase Array

// add method to drop student
//Remove Student from course

int removeStudent = -1;{

for (int i = 0; i < NumberOfStudents; i++) {
if (students[i].equals(students)) {
removeStudent= i;
if (removeStudent!= -1) {
for (i = removeStudent; i < NumberOfStudents; i++)
students[i] = students[i+1];
} // end if found
  
// decrement number of students by 1
NumberOfStudents--;
}
}

int clear = 0; {

for (int i = 0; i < NumberOfStudents; i ++){
students [i] = null;
NumberOfStudents = 0;
}
  
}
}
}

Solution

import java.util.ArrayList; public class Course { //Create Students public String courseName; public ArrayList students; private int NumberOfStudents; //Add Course public Course(String courseName) { this.courseName = courseName; students = new ArrayList<>(); } public void addStudent(String student) { students = new ArrayList<>(); students.add(student); NumberOfStudents++; } //Return Student public String[] getStudents() { return (String[]) students.toArray(); } public int getNumberOfStudents() { return NumberOfStudents; } public String getcoursName() { return courseName; } public void dropStudent(String student) { for (int i = 0; i < NumberOfStudents; i++) { if (students.get(i).equals(student)) { // Move students[i + 1] to students[i], etc. for (int k = i + 1; k < NumberOfStudents; k++) { students.set(k - 1, students.get(k)); } NumberOfStudents--; break; } } } // add method to drop student //Remove Student from course int removeStudent = -1; { for (int i = 0; i < NumberOfStudents; i++) { if (students.get(i).equals(students)) { removeStudent = i; if (removeStudent != -1) { for (i = removeStudent; i < NumberOfStudents; i++) students.set(i, students.get(i + 1)); } // end if found // decrement number of students by 1 NumberOfStudents--; } } int clear = 0; { for (int i = 0; i < NumberOfStudents; i++) { students.set(i, null); NumberOfStudents = 0; } } } }