Mobile Technologies Web Technologies Digital Marketing Creative Design Career Talk Medical General Tech Interviews Internet Of Things

Embark on a journey of knowledge! Take the quiz and earn valuable credits.

Take A Quiz

Challenge yourself and boost your learning! Start the quiz now to earn credits.

Take A Quiz

Unlock your potential! Begin the quiz, answer questions, and accumulate credits along the way.

Take A Quiz

Popular Categories

Interview Questions
QuestionBank
Quantitative Aptitude
Engineering
Digital Marketing
Management
Govt Exams
Interviews
All

Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop

Mobile Technologies Mobile Computing 2 years ago

0 1 0 0 0 tuteeHUB earn credit +10 pts
5 Star Rating 1 Rating
_x000D_ _x000D_ We all know you can't do this: for (Object i : l) { if (condition(i)) { l.remove(i); } } ConcurrentModificationException etc... this apparently works sometimes, but not always. Here's some specific code: public static void main(String[] args) { Collection l = new ArrayList<>(); for (int i = 0; i < 10; ++i) { l.add(4); l.add(5); l.add(6); } for (int i : l) { if (i == 5) { l.remove(i); } } System.out.println(l); } This, of course, results in: Exception in thread "main" java.util.ConcurrentModificationException ... even though multiple threads aren't doing it... Anyway. What's the best solution to this problem? How can I remove an item from the collection in a loop without throwing this exception? I'm also using an arbitrary Collection here, not necessarily an ArrayList, so you can't rely on get.
Previous Next

Posted on 16 Aug 2022, this text provides information on Mobile Computing related to Mobile Technologies. Please note that while accuracy is prioritized, the data presented might not be entirely correct or up-to-date. This information is offered for general knowledge and informational purposes only, and should not be considered as a substitute for professional advice.

Take Quiz To Earn Credits!

Turn Your Knowledge into Earnings.

tuteehub_quiz

Answers (1)

Post Answer
profilepic.png
manpreet Tuteehub forum best answer Best Answer 2 years ago
_x000D_ Iterator.remove() is safe, you can use it like this: List list = new ArrayList<>(); // This is a clever way to create the iterator and call iterator.hasNext() like // you would do in a while-loop. It would be the same as doing: // Iterator iterator = list.iterator(); // while (iterator.hasNext()) { for (Iterator iterator = list.iterator(); iterator.hasNext();) { String string = iterator.next(); if (string.isEmpty()) { // Remove the current element from the iterator and the list. iterator.remove(); } } Note that Iterator.remove() is the only safe way to modify a collection during iteration; the behavior is unspecified if the underlying collection is modified in any other way while the iteration is in progress. Source: docs.oracle > The Collection Interface And similarly, if you have a ListIterator and want to add items, you can use ListIterator#add, for the same reason you can use Iterator#remove — it's designed to allow it. In your case you tried to remove from a list, but the same restriction applies if trying to put into a Map while iterating its content.
0 views
0 shares

No matter what stage you're at in your education or career, TuteeHub will help you reach the next level that you're aiming for. Simply,Choose a subject/topic and get started in self-paced practice sessions to improve your knowledge and scores.

Q

What is the full form of NABARD ?

Banking, Finance & Insurance
Q

How to refresh app upon shaking the device?

Mobile Technologies
Q

What are the govt exams after BCA?

Career Talk
Q

TYPO3 v8. Override function in Core class

General Tech
Q

Why do people in India give so much importance to Government jobs?

Commerce & Accounting

Explore Other Libraries

Blogs Tutorials Question Bank Feeds Careernews

Related Searches

Collection avoiding ConcurrentModificationException objects loop

Important Mobile Technologies Links

 Mobile Computing