ArrayList in java

/*
 * Java ArrayList class uses a dynamic array for storing the elements.It extends AbstractList class and implements List interface.
 * Can contain duplicate elements.
 * Maintains insertion order.
 * Non synchronized.
 * Allows random access because array works at the index basis.
 * Manipulation is slow because a lot of shifting needs to be occurred if any element is removed from the array list.
*/

package collection.list;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

public class ArrayListDemo {
    public ArrayListDemo() {
        super();
    }
   
    public static void main(String args []){
       
/*
 * creating old non-generic arraylist
 */
        ArrayList al=new ArrayList();
       
/*
 * ArrayList with normal data or objects of int,string etc (generic arraylist )
*/
        simpleArrayCheck();

/*
 * ArrayList of objects of employee class and uses Comparable interface for sorting
*/
        ArrayList<Employee> empList = EmployeeObjArrayList();
//        removeEmployee(empList,41);
/*
 *  ArrayList of objects of Student class and uses Comparator interface for sorting
*/
//        StudentObjArrayList();
       
    }
   
   public static void removeEmployee(ArrayList<Employee> arr,Integer empId){
        Iterator iter = arr.iterator();
        while(iter.hasNext()){
           Employee emp = (Employee)iter.next();
           if(emp.getEmpId()==empId){
               arr.remove(emp);
               System.out.println("Employee "+empId + "deleted");
               break;
           }
       }
       
    }
   
    public static void simpleArrayCheck(){
        ArrayList<Integer> arr= new ArrayList<Integer>();
        arr.add(5);
        arr.add(11);
        arr.add(1);
        arr.add(9);
        arr.add(30);
        Iterator iterator = arr.iterator();
        while(iterator.hasNext()){
            System.out.println(iterator.next());
        }
        Collections.sort(arr);
        System.out.println("----------After Sorting----------");
        Iterator iter = arr.iterator();
        while(iter.hasNext()){
            System.out.println(iter.next());
        }
       
    }
   
    public static ArrayList<Employee> EmployeeObjArrayList(){
       
        ArrayList<Employee> employee = new ArrayList<Employee>();
        employee.add(new Employee(12,"Bipasha","AB+"));   //int empId,String employeeName,String bloodGroup
        employee.add(new Employee(25,"Kenith","B+"));
        employee.add(new Employee(82,"Alia","A-"));
        employee.add(new Employee(41,"Priti","AB-"));
        employee.add(new Employee(20,"John","B-"));
        employee.add(new Employee(89,"Khali","AB-"));
        for(Employee emp:employee ){
            System.out.println(emp);
        }
        Collections.sort(employee);
        System.out.println("After Sorting Employee Objects");
            for(Employee emp:employee ){
                System.out.println(emp);
            }
            return employee;
    }

    private static List<Student> StudentObjArrayList() {
        List<Student> student = new ArrayList<Student>();
        student.add(new Student(12,"sachin","AB+"));   //int empId,String employeeName,String bloodGroup
        student.add(new Student(25,"Rahul","B+"));
        student.add(new Student(82,"Gaurav","A-"));
        student.add(new Student(41,"Dravid","AB-"));
        student.add(new Student(20,"Dhoni","B-"));
        student.add(new Student(89,"Mohan","AB-"));
        for(Student emp:student ){
            System.out.println(emp);
        }
        Collections.sort(student,new Student());
        System.out.println("After Sorting Employee Objects");
            for(Student emp:student ){
                System.out.println(emp);
            }
            return student;
  }
 
}