How is the next thread to be executed in java selected?

Question

Java

I will give an example - there are one hundred threads. All of them work with one object. When a thread obtains execution rights, it completely locks the object and releases it only after it has done all the necessary work. The question is - can I be sure what we say in 5 minutes. program work, did all threads capture the object approximately the same number of times? Those. can it happen that some thread will be allowed to work with an object 100 times, and another only 20?