Difference between Iterator and List Iterator Example

/*

 *    Iterator traverse elements only in one direction i.e forward

 *    ListIterator traverse elements in both directions i.e forward and backward

 *    Using ListIterator we can modify the existing list as well as done in below sample

 */




public class IteratorClass extends Activity

{



ArrayList<String> miteratorList;

Iterator<String> mIterator;

ListIterator<String> mListIterator;



@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

initiViews();

}



private void initiViews()

{

//Initializing the ArrayList 

miteratorList=new ArrayList<String>();



//Adding values to the ArrayList

miteratorList.add("A");

miteratorList.add("B");

miteratorList.add("C");

miteratorList.add("D");

miteratorList.add("E");





//method to traverse elements using Iterator here

usingIterator();



//Initializing the mListIterator here

mListIterator=miteratorList.listIterator();



//method to traverse and modify elements using mListIterator here

usingListIterator();



//method to traverse elements using Iterator here

usingIterator();



usingListIteratorTOTraverseBackward();



}





private void usingIterator()

{

//Initializing the mIterator here

mIterator=miteratorList.iterator();//Returns an iterator on the elements of this list.

while(mIterator.hasNext())

{

Object element = mIterator.next();

System.out.print(element + " ");

}



//O/P goes like this => 04-29 18:32:44.590: I/System.out(26302): A B C D E



System.out.println();

}





private void usingListIterator()

{

//Modifying the existing list using list iterator

while (mListIterator.hasNext()) {

Object element=mListIterator.next();

mListIterator.set(element+"Z");  

}



System.out.println();



//04-29 18:45:44.588: I/System.out(1605): AZ BZ CZ DZ EZ



}





private void usingListIteratorTOTraverseBackward()

{

// Now, display the list in reverse order using ListIterator

      while(mListIterator.hasPrevious()) {

         Object element = mListIterator.previous();

         System.out.print(element + " ");

       }

       System.out.println();

      

          // 04-29 18:52:30.478: I/System.out(5954): EZ DZ CZ BZ AZ



}



}