Removing element in ArrayList using INDEX causing java.util.ConcurrentModificationException

Question

The following code is causing

java.util.ConcurrentModificationException

I am not sure how to solve the error please help !

ArrayList strList =  new ArrayList<String>(Arrays.asList(cmd.split(" ")));

        if (strList.get(0).equals("LIST")) {

        }

        if (strList.get(0).equals("DEPEND")) {
            strList.remove(0); // getting error at this point 
            cm.createComponent(strList);

        }

Full Method The outer loop is not related to the List

public static void main(String[] args) throws IOException {
        ComponentManager cm = new ComponentManager();

    List<String> lines = Files.readAllLines(Paths.get("cmdList.txt"));
    for (String cmd : lines) {
        ArrayList strList =  new ArrayList<String>(Arrays.asList(cmd.split(" ")));

        if (strList.get(0).equals("LIST")) {

        }

        if (strList.get(0).equals("DEPEND")) {
            strList.remove(0);
            cm.createComponent(strList);

        }

        if (strList.get(0).equals("INSTALL")) {

        }

        if (strList.get(0).equals("REMOVE")) {

        }

    }

}

Can you show us full stack trace? It is like there is another problem. — aios, Sep 27 '16 at 06:18
@JimGarrison But since the list is wrapped in an `ArrayList`, the OP shouldn't be seeing `UnsupportedOperationException` either. Definitely a case of missing details from the question. — nbrooks, Sep 27 '16 at 06:19
Are you sure that not somewhere there is a `lines.remove(0);` or list assignment. If you are working in the NetBeans IDE, you can run FindBugs by Source -> Inspect. — Joop Eggen, Sep 27 '16 at 06:29
You're checking `strList.get(0)` after changing the `strList` this can lead to some kind of other problems. Maybe it'd be more suitable to use switch on string? — Mikhail Kuchma, Sep 27 '16 at 07:19

score 1 · Answer 1 · edited May 23 '17 at 12:06

1

You can create a different ArrayList and perform remove operation there or put up an iterator on the arrayList and remove using the iterator.

Find a couple of potential solutions to your problem here and here.

edited May 23 '17 at 12:06

Community

1
1

answered Sep 27 '16 at 06:43

Akash Mishra

682
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Removing element in ArrayList using INDEX causing java.util.ConcurrentModificationException

1 Answers1