Are Comparators Thread Safe?

Instances of FixedOrderComparator are not synchronized. The class is not thread-safe at construction time, but it is thread-safe to perform multiple comparisons after all the setup operations are complete.

Is comparator comparing thread-safe?

Most Comparator implementations do no such thing, but one scenario that might reasonably occur is using a SimpleDateFormat to compare Strings that represent dates. Unfortunately, SimpleDateFormat itself is not thread safe. Comparator is an interface, it has no inherent concurrency properties.

Is multithreaded thread-safe?

Thread safe: Implementation is guaranteed to be free of race conditions when accessed by multiple threads simultaneously. Conditionally safe: Different threads can access different objects simultaneously, and access to shared data is protected from race conditions.