为什么并发修改异常不会在并发包中抛出？

Question

Classes like ConcurrentHashmap will not throw this exception; why? What are they doing internally to avoid this exception? How can I prevent this for all classes in the concurrent API?

Answer 1

Concurrent collections implementations Iterators do not throw ConcurentModificationException because this is API's requirement, see java.util.concurrent package javadocs. Different implementations use different techniques to achieve that, eg creating a snapshot of the state of the collection. You can see JDK source code for implementation details.