Adding elements to ArrayList while using Iterator in Java

Question

I had a problem with adding elements to my ArrayList while using an Iterator. In the following code it gives me this output:

a
k
s

But still it misses the one I had added through iterator. i.e I am missing r in my output. Is there a way I can add elements to an ArrayList using an Iterator?

import java.util.ArrayList;
import java.util.ListIterator;
public class Test 
{
public static void main(String args[])
{
    ArrayList<String> array_test= new ArrayList<String>();
    array_test.add("a");
    array_test.add("k");
    array_test.add("d");
    array_test.add("s");
    array_test.remove("d");
    ListIterator<String> it=array_test.listIterator();
    while(it.hasNext())
    {   
        String link=it.next();  
        it.add("r");
        System.out.println(link);

    }   
    //System.out.println("Contents of arrays list "+array_test);
}


}

What do you expect your output to be ?

nyxz
– nyxz

2011-11-07 08:36:00 +00:00
Commented Nov 7, 2011 at 8:36 — nyxz
– nyxz, Commented Nov 7, 2011 at 8:36

user207421 · Accepted Answer · 2011-11-07 08:05:41Z

2

Check the Javadoc. It is working as documented. Adding an element during an iteration doesn't return that element via the iterator unless you go backwards.

edited Nov 7, 2011 at 8:05

answered Nov 7, 2011 at 7:56

user207421

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10 Comments

prashanth Over a year ago

Thanks for you replay. i am unable to add new elements when i tried using iterator. as i specified, i was trying to add r in while loop. which is not working.

Björn Pollex Over a year ago

-1: You should at least quote the relevant part from the documentation.

jbrookover Over a year ago

It is working. The second print statement, which you have commented out, should include all four letters.

user207421 Over a year ago

@BjörnPollex I disagree completely. The documentation is there to be read. The specification or the wording may change slightly, which would make the quotation obsolete. The point here is that the OP hasn't understood or more probably even read the Javadoc at all.

user207421 Over a year ago

@jbrookover your comment is irrelevant to my answer. If you have an answer of your own I suggest you post it.

|

prashanth · Accepted Answer · 2014-10-22 03:21:38Z

1

Sorry for my late reply. Here is how i resolved this issue.

for(ListIterator it=array_test.listIterator();it.hasNext();){ 
 String link=it.next(); 
   it.add("r");
   it.previous();
   it.add("kk");
   it.previous();
System.out.println(link);  
}

answered Oct 22, 2014 at 3:21

prashanth

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1 Comment

lmat - Reinstate Monica Over a year ago

Glad you got it sorted out after those three years! But this doesn't look like it'll terminate. Each time around the loop, you take one item off and add two?

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