How do you resolve concurrent modification exception?

How do you resolve concurrent modification exception?

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.

How can we avoid ConcurrentModificationException in a multi-threaded environment?

To Avoid ConcurrentModificationException in multi-threaded environment

1. You can convert the list to an array and then iterate on the array.
2. You can lock the list while iterating by putting it in a synchronized block.
3. If you are using JDK1.

Which method of iterator throws ConcurrentModificationException?

The iterators returned by ArrayList iterator() and listIterator() methods are fail-fast: if the list is structurally modified at any time after the iterator is created, in any way except through the iterator’s own remove or add methods, the iterator will throw a ConcurrentModificationException .

What does Java Util ConcurrentModificationException mean?

The java. util. concurrentmodificationexception is an error in Java. The error occurs when the iterator is traversing a list, and a command is used to change an element’s value during that traversal.

Why do we get concurrent modification exception?

The ConcurrentModificationException occurs when an object is tried to be modified concurrently when it is not permissible. This exception usually comes when one is working with Java Collection classes. For Example – It is not permissible for a thread to modify a Collection when some other thread is iterating over it.

How do you prevent concurrent modification exception on a map?

use ConcurrentHashMap. keep on using simple HashMap, but build a new map on each modification and switch maps behind the scenes (synchronizing the switch operation or using AtomicReference)

How ConcurrentHashMap internally works in Java with example?

ConcurrentHashMap: It allows concurrent access to the map. Part of the map called Segment (internal data structure) is only getting locked while adding or updating the map. So ConcurrentHashMap allows concurrent threads to read the value without locking at all. This data structure was introduced to improve performance.

What is Java Util NoSuchElementException?

The NoSuchElementException in Java is thrown when one tries to access an iterable beyond its maximum limit. The exception indicates that there are no more elements remaining to iterate over ​in an enumeration. The NoSuchElementException is thrown by the following: iterator::next()

Can we modify collection while iterating?

In for-each loop, we can’t modify collection, it will throw a ConcurrentModificationException on the other hand with iterator we can modify collection.

What is the advantage of ConcurrentHashMap?

The advantages of using ConcurrentHashMap are as follows: It provides very high concurrency in a multi-threaded environment. The read operation can be very fast when the write operation is done with a lock. It provides No object-level Locking.