example use of Iterator type in java language

TryIterator.java

import java.util.*;

// Try compile with `javac` & `javac -Xlint`

class TryIterator {
    public static void main(String args[]) {
        // create an array list
        ArrayList<String> al = new ArrayList();
        
        // add elements to the array list
        al.add("C"); al.add("A"); al.add("E"); al.add("B"); al.add("D"); al.add("F");

        // to print all Element use `for each`
        System.out.println("Original contents (foreach): ");
        
        // it reads, for every `String it` in List `al`
        for(String it: al) {
            System.out.print(it);
        }
        System.out.println("");

        // foreach is same as iterator
        // use iterator to display contents of al
        System.out.print("Original contents of al: ");
        Iterator itr = al.iterator();        
        while (itr.hasNext()) {
            Object element = itr.next();
            System.out.print(element + " ");
        }
        // add enter
        System.out.println();
        
        // litr saved the refference memory (pointer) to `al` object
        // modify objects being iterated
        ListIterator litr = al.listIterator();
        while (litr.hasNext()) {
            Object element = litr.next();
            litr.set(element + "+");
        }
        
        System.out.print("Modified contents of al: ");
        
        itr = al.iterator();
        
        while (itr.hasNext()) {
            Object element = itr.next();
            System.out.print(element + " ");
        }
        
        // enter
        System.out.println();
        
        // now, display the list backwards
        System.out.print("Modified list backwards: ");
        while (litr.hasPrevious()) {
            Object element = litr.previous();
            System.out.print(element + " ");
        }

        System.out.println();
    }   
}