ArrayList and Iterator , including Array examples

ArrayList and Iterator
Below examples include ArrayList and Iterator including some code/example for Array also since all these are closely related and look similar.

package newPkg;

import java.util.ArrayList;

import java.util.Iterator;

public class NewClass {

      public static void main(String[] args) {

           

            String[] stArray = new String[6];

            int[] intArray = new int[7];

            ArrayList arList1 = new ArrayList(); //or

            ArrayList arList2 = new ArrayList<>(); //or

            ArrayList arList4 = new ArrayList<>(); //or

            ArrayList arList3 = new ArrayList();

//          List arList4 = {"A","B","C","D"};

           

            stArray[0] = "Ram";

            intArray[0] = 100;

            arList1.add("Sita");

           

            stArray[1] = "Shyam";

            intArray[1] = 200;

            arList1.add(1,"Radha"); //with index of the data

           

            stArray[2] = "USA";

            intArray[2] = 300;

            arList2.add("DC");

           

            stArray[3] = "Canada";

            intArray[3] = 400;

            arList2.add(1,"NY");//with index of the data

            arList2.add(2,"Toranto");//with index of the data

           

            arList3.add(5);

            arList3.add(1,"Africa");

            arList3.add(1);

            arList3.add("11");

           

            arList4.add(11);

            arList4.add(12);

            arList4.add(13);

            arList4.add(14);

           

            //itrating over an array

            //use for loop

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

                  String x = stArray[i];

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

            }

            //or

            for (String j:stArray){

                  String y = j;

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

            }

            Iterator itr1 = arList1.iterator();

            System.out.println("itr1 = "+itr1);

           

            Iterator itr2 = arList2.iterator();

            System.out.println("itr2 = "+itr2);

           

            Iterator itr3 = arList3.iterator();

            System.out.println("itr3 = "+itr3);

           

            Iterator itr4 = arList4.iterator();

            System.out.println("itr4 = "+itr4);

           

            //finding values of array list , three ways :

            for(int i=0;i<arList3.size();i++){

                  System.out.println("arList3Values = "+arList3.get(i));

            }

            //or

          for (Integer arList4Values : arList4) {                 

                 System.out.println("arList4Values = "+arList4Values);            

          }

           

          //or

          System.out.println("list value 1 = "+itr3.hasNext());

          System.out.println("list value 2 = "+itr3.hasNext());

          System.out.println("list value 3 = "+itr3.hasNext());

          if(itr3.hasNext()){

            System.out.println("list value random1 = "+itr3.next());

          }

          if(itr3.hasNext()){

            System.out.println("list value random2 = "+itr3.next());

          }

          if(itr3.hasNext()){

            System.out.println("list value random3 = "+itr3.next());

          }

          if(itr3.hasNext()){

            System.out.println("list value random4 = "+itr3.next());

          }

          if(itr3.hasNext()){

            System.out.println("list value random5 = "+itr3.next());

          }

          if(itr3.hasNext()){

            System.out.println("list value random6 = "+itr3.next());

          }

          //below while is skipped because itr3.hasNext() is false

          while (itr3.hasNext()) {

               System.out.println("from while "+itr3.next());

            }

           

          System.out.println("list value 1 = "+itr3.hasNext());

          System.out.println("list value 2 = "+itr3.hasNext());

          System.out.println("list value 3 = "+itr3.hasNext());

         

          if(itr4.hasNext()){

            System.out.println("4th iteration value random1 = "+itr4.next());

          }

          if(itr4.hasNext()){

            System.out.println("4th iteration  value random2 = "+itr4.next());

          }

          //below while prints two values only , since two are already printed by above statements

          while (itr4.hasNext()) {

               System.out.println("4th iteration  from while "+itr4.next());

            }

      }

}

OUTPUT

 x = Ram
x = Shyam
x = USA
x = Canada
x = null
x = null
y = Ram
y = Shyam
y = USA
y = Canada
y = null
y = null
itr1 = java.util.ArrayList$Itr@15db9742
itr2 = java.util.ArrayList$Itr@6d06d69c
itr3 = java.util.ArrayList$Itr@7852e922
itr4 = java.util.ArrayList$Itr@4e25154f
arList3Values = 5
arList3Values = Africa
arList3Values = 1
arList3Values = 11
arList4Values = 11
arList4Values = 12
arList4Values = 13
arList4Values = 14
list value 1 = true
list value 2 = true
list value 3 = true
list value random1 = 5
list value random2 = Africa
list value random3 = 1
list value random4 = 11
list value 1 = false
list value 2 = false
list value 3 = false
4th iteration value random1 = 11
4th iteration  value random2 = 12
from while 13
from while 14