Some good answers here, but as far as I can tell no-one has actually provided a canonical answer to the question asked: “Is ConcurrentHashMap.get() guaranteed to see a previous ConcurrentHashMap.put() by different thread”. Those that have said yes haven’t provided a source.
So: yes, it is guaranteed. Source (see the section ‘Memory Consistency Properties’):
Actions in a thread prior to placing an object into any concurrent collection happen-before actions subsequent to the access or removal of that element from the collection in another thread.