How to add elements to an empty list using ListIterator?

Question

I have coded the following to add elements to the empty list using the ListIterator:

ArrayList<String> list = new ArrayList<String>();
ListIterator<String> listIterator = list.listIterator();

public void append(String... tokens) {

        if(tokens == null)
            return;

        // append tokens at the end of the stream using the list iterator
        for(int i = 0 ; i < tokens.length ; ++i){

            // if the token is not null we append it 
            if(tokens[i] != null && !tokens[i].equals(""))
                listIterator.add(tokens[i]);
        }

        reset();
    }

I want to add elements to this empty list using the listIterator and then after adding all the elements I want to move the iterator to the beginning of the list and I also want to be able to remove the elements where the iterator points, for some reason my method doesn't seem to work, kindly help.

John Zeringue · Accepted Answer · 2013-09-26 01:01:09Z

2

Perhaps I'm not understanding your problem, but it seems like you really want to have...

list.add(tokens[i]);

instead of...

listIterator.add(tokens[i]);

answered Sep 26, 2013 at 1:01

John Zeringue

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2 Comments

AnkitSablok Over a year ago

I actually want to add elements to the iterator using listIterator to avoid the ConcurrentModificationException , that is why I am using a listIterator

John Zeringue Over a year ago

Could you be more specific about what's not working? One possible bug (perhaps it's intended) is ++i instead of i++.

SuperCamp · Accepted Answer · 2013-09-26 02:30:34Z

0

After you are done adding items to the iterator, get new instance of the iterator and start again. What is the reset() method supposed to do?

You will not get a ConcurrentModificationException unless you modify the list you are looping through.

Maybe this is what you are looking for.

    ArrayList<String> list = new ArrayList<String>();
    ListIterator<String> listIterator = list.listIterator();
    String[] tokens = {"test", "test1", "test2"};

    // append tokens at the end of the stream using the list iterator
    for (int i = 0; i < tokens.length; ++i) {

        // if the token is not null we append it
        if (tokens[i] != null && !tokens[i].equals(""))
            listIterator.add(tokens[i]);
    }

    while (listIterator.hasPrevious()) {
        if(listIterator.previous().toString().equals("test1")) {
            listIterator.remove();
        }
    }

    while (listIterator.hasNext()) {
        System.out.println(listIterator.next().toString());
    }

edited Sep 26, 2013 at 2:30

answered Sep 26, 2013 at 1:22

SuperCamp

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3 Comments

AnkitSablok Over a year ago

The reset method is used to set the iterator to the beginning of the list

SuperCamp Over a year ago

Does it return a new iterator? How are you resetting it?

AnkitSablok Over a year ago

while(listIterator.hasPrevious())listIterator.previous();

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