How does ArrayList behave in multithreaded code?

ArrayList is a resizable array implementation of the List interface in Java. In a multithreaded environment, using ArrayList can lead to inconsistency and unpredictable behavior. This occurs because multiple threads may try to read from and write to the list simultaneously without proper synchronization, leading to potential data corruption or exceptions such as ConcurrentModificationException.

To safely use ArrayList in multithreaded scenarios, it is crucial to implement synchronization mechanisms such as using Collections.synchronizedList() or using Concurrent data structures like CopyOnWriteArrayList, which is designed specifically for concurrent access.

// Example of using synchronized ArrayList List synchronizedList = Collections.synchronizedList(new ArrayList<>()); synchronizedList.add("Item 1"); synchronizedList.add("Item 2"); synchronized (synchronizedList) { for (String item : synchronizedList) { System.out.println(item); } }

ArrayList multithreading synchronization concurrent modification Java Collections.synchronizedList CopyOnWriteArrayList

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