remove element from list of strings?

Question

AH! I have a list of strings... and i just want to remove an element from the list if it is ""

but i keep causing the program to crash. How do i get around this? I made a list of arrays into a List of strings thinking i could remove it that way. Here is what i have:

        List<String>list;

        String[] f= new String[file.length()];
        f= file.split("<"); 

        list= Arrays.asList(f); 

        final Iterator<String> iter = list.iterator();
        while (iter.hasNext()) 
        {
            final String temp = iter.next();
            // TODO check for zero-length arrays
            if (temp.equals("")) 
            {
                iter.remove();
            }
        }

Error:

Exception in thread "main" java.lang.UnsupportedOperationException
    at java.util.AbstractList.remove(Unknown Source)
        at java.util.AbstractList$Itr.remove(Unknown Source)
        at utilities.Validation.Validate(Validation.java:44)

After i convert it to a List, i can print the list just fine.. it's removing elements from it that becomes an problem...

Why are you using the final keyword? Have you tried removing them? — Bernard
– Bernard, Commented Mar 25, 2012 at 0:37
@ Bernard, it doesn't make a difference if it's there or not in terms of the exception — BigBug
– BigBug, Commented Mar 25, 2012 at 0:39

Jeffrey · Accepted Answer · 2012-03-25 00:41:20Z

13

The List returned by Arrays#asList has a fixed size. Since removeing an element would modify the length, it is unsupported. If you want a List that allows removal of items, use new ArrayList<>(Arrays.asList(array));.

answered Mar 25, 2012 at 0:41

Jeffrey

44.9k8 gold badges93 silver badges143 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Natix · Accepted Answer · 2012-03-25 01:59:51Z

1

The reason why you were getting the exception has already been answered, but I add a little note about your code: You can remove all empty strings from a list in a much simpler way using the removeAll() method. You don't even have to check if the given array is empty, because this method can handle them.

String[] array = { "aa", "", "cc", "", "d" };
List<String> list = new ArrayList<String>(Arrays.asList(array));

list.removeAll(Collections.singleton(""));
System.out.println(list);

Which prints:

[aa, cc, d]

answered Mar 25, 2012 at 1:59

Natix

14.3k7 gold badges57 silver badges69 bronze badges

Comments

Eugene Retunsky · Accepted Answer · 2012-03-25 02:26:41Z

0

Arrays.asList produces a list that doesn't allow adding or removing elements.

If there is a lot elements to remove then here is a quick way to do that:

List<String> result = new ArrayList<String>();
for (String next : file) {
   if (next != null && next.length() != 0) result.add(next);
}

edited Mar 25, 2012 at 2:26

answered Mar 25, 2012 at 0:41

Eugene Retunsky

13.2k5 gold badges54 silver badges55 bronze badges

2 Comments

Jeffrey Over a year ago

The List returned from Arrays#asList is modifiable. You are allowed to set items.

Eugene Retunsky Over a year ago

I meant you cannot remove or add elements (in context of the question). I.e. the structure is not modifiable, while elements, yes, are.

Collectives™ on Stack Overflow

remove element from list of strings?

3 Answers 3

Comments

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related