A hammer tool can only be used by one technician at a time to perform hitting. Accordingly, you have developed a Hammer class with a hit method. Objects of class Hammer are used to simulate different hammers, while threads are created to simulate users. Which situation needs to add the synchronized keyword to the hit method

Explanation:

The synchronized keyword needs to be active on the hit method at any point where 2 or more threads (users) exists at any given moment. This is in order to prevent two or more users from trying to perform a hammer hit at the same time. This is what the synchronized keyword is used for. It prevents the more than one thread from calling the specific method at the same time. Instead it adds the action to a sequence so that the second thread calls the hit method only after the first thread's hit method finishes.

ok that sounds like a app that my brother would like

i've had the same problem. i generally just ignore it, as a ton of these "verified answers" are completely wrong.