How is it possible to get ConcurrentModificationException exception from single threaded code?

If a single thread issues a sequence of method invocations that violates the contract of an object, the object may throw this exception. For example, if a thread modifies a collection directly while it is iterating over the collection with a fail-fast iterator, the iterator will thow this exception.”

How can we avoid ConcurrentModificationException in a single threaded environment?

To Avoid ConcurrentModificationException in single-threaded environment. You can use the iterator remove() function to remove the object from underlying collection object. But in this case, you can remove the same object and not any other object from the list.

How do I fix ConcurrentModificationException in Java?

How to avoid ConcurrentModificationException in a multi-threaded environment?

1. Instead of iterating over the collection class, we can iterate over the array.
2. Another way can be locking the list by putting it in the synchronized block.
3. JDK 1.5 or higher provides with ConcurrentHashMap and CopyOnWriteArrayList classes.

What causes Java Util ConcurrentModificationException?

Class ConcurrentModificationException. This exception may be thrown by methods that have detected concurrent modification of an object when such modification is not permissible. For example, it is not generally permissible for one thread to modify a Collection while another thread is iterating over it.

When do I get ConcurrentModificationException in Java?

This exception is rise when an object is tried to be modified concurrently when it is not permissible i.e when one thread is iterating over some collection class object and if some other thread tried to modify or try to make some changes on that collection object then we will get ConcurrentModificationException.

How to avoid ConcurrentModificationException in single threaded environment?

To Avoid ConcurrentModificationException in single-threaded environment. You can use the iterator remove() function to remove the object from underlying collection object. But in this case, you can remove the same object and not any other object from the list.

How to avoid concurrent modification exception in jdk1.5?

This approach is not recommended because it will cease the benefits of multithreading. If you are using JDK1.5 or higher then you can use ConcurrentHashMap and CopyOnWriteArrayList classes. This is the recommended approach to avoid concurrent modification exception.

Can a concurrent collection class be modified safely?

Concurrent Collection classes can be modified safely, they will not throw ConcurrentModificationException. In case of CopyOnWriteArrayList, iterator doesn’t accommodate the changes in the list and works on the original list. It is taking the new object added with key “4” but not the next added object with key “5”.