Problem with remove() method of ArrayList collection

Question

Dear All,
I have a program below: See the statement in bold
//Start of the Program
import java.util.*;
public class ArrayListTest
     public static void main(String args[])
          //declare an arraylist of type String
          List<String> stringStorage = new ArrayList<String>();
          //add elements to the ArrayList
          stringStorage.add("apple");
          stringStorage.add("banana");
          stringStorage.add("papaya");
          stringStorage.add("peach");
          stringStorage.add("cucumber");
          stringStorage.add("orange");
          stringStorage.add("grapes");
          stringStorage.add("plum");
          stringStorage.add("chiku");
          stringStorage.add("pomegrenate");
          stringStorage.add("pomegrenate2");
          //iterate through the ArrayList
          Iterator<String> iterate = stringStorage.iterator();
          //test whether an element is present
          boolean isPresent = stringStorage.contains("xxx");
          System.out.println("xxx is Present "+isPresent);
          //remove an element from the ArrayList
Line no: 12     System.out.println("Remove apple:(true/false)"+stringStorage.remove("apple"));
          Loop:
          for (int i=0;i<stringStorage.size();i++)
               while (iterate.hasNext()==true)
                    System.out.println("Element in the arraylist["+i+"] "+iterate.next());
                    //iterate.remove();
                    continue Loop;
End of Outer Loop:
//End of the Program
It compiles fine. But when I try to run , it gives a unchecked exception in main ConcurrentModificationException.
Exception in thread "main" java.util.ConcurrentModificationException
at java.util.AbstractList$Itr.checkForComodification(Unknown Source)
at java.util.AbstractList$Itr.next(Unknown Source)
at ArrayListTest.main(ArrayListTest.java:48)
But, if I remove Line no 12(in bold), or put the same statement after End of Outer Loop: , I do not get the error. Can you explain this phenomenon?

Answer 1

look what you do:
1/ you retrieve the iterator
2/ you remove apple
3/ you browse the iterator
but actually, the iterator kept a reference to the "apple" you just removed ; that s why it gets screwed ;
you mustn't operate on the list if you re not over with the iterator work