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How is concurrent modification exception thrown?
If we invoke a sequence of methods on an object that violates its contract, then the object throws ConcurrentModificationException. For example: if while iterating over the collection, we directly try to modify that collection, then the given fail-fast iterator will throw this ConcurrentModificationException.
Which Iterator can throw a concurrent modification exception?
Fail-Fast iterators
Fail-Fast iterators immediately throw ConcurrentModificationException if there is structural modification of the collection. Structural modification means adding, removing any element from collection while a thread is iterating over that collection.
What is the concurrent modification exception in Java stack overflow?
For example, if a thread modifies a collection directly while it is iterating over the collection with a fail-fast iterator, the iterator will throw this exception.
What Iterator can throw a concurrent modification exception Mcq?
The Fail Fast iterator throws a ConcurrentModificationException if a collection is modified while iterating over it. The Fail Fast iterator uses an original collection to traverse over the collection’s elements.
Is ListIterator fail fast?
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 .
How can we avoid ConcurrentModificationException in a multi threaded environment?
To Avoid ConcurrentModificationException in multi-threaded environment
- You can convert the list to an array and then iterate on the array.
- You can lock the list while iterating by putting it in a synchronized block.
- If you are using JDK1.
What is 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 handle concurrent modification exception in ArrayList?
When you are iterating over ArrayList then Iterator’s next() method keep track of modCount. If you modify the collection by adding or removing elements then modCount will change and it will not match with the expected modCount, hence Iterator will throw ConcurrentModificationException.
When do you use exception in Java?
Exception Object. An exception object is an instance of an exception class. It gets created and handed to the Java runtime when an exceptional event occurred that disrupted the normal flow of the application. This is called “to throw an exception” because in Java you use the keyword “throw” to hand the exception to the runtime.
What is ConcurrentModificationException Java?
Concurrent Modification Exception (java.util.ConcurrentModificationException) is a Runtime Exception (java.util.Runtime) which may be thrown by the methods that have detected concurrent modifications of an object, when such modification is not allowed.
What are runtime exceptions in Java?
Runtime Exception is the parent class in all exceptions of the Java programming language that are expected to crash or break down the program or application when they occur. Unlike exceptions that are not considered as Runtime Exceptions, Runtime Exceptions are never checked.
What is Io exception in Java?
Java IO Exception Handling From Java 7. From Java 7 on and forward Java contains a new exception handling mechanism called “try with resources”. This exception handling mechanism is especially targeted at handling exception handling when you are using resources that need to be closed properly after use, like InputStream, OutputStream etc.