IBM Software Developer interview questions

What is Synchronisation? In OS

What happens if you call super() inside a constructor after a this() call? Will it compile? Why or why not? If you insert the same object multiple times into a HashSet but its hashCode() changes after insertion, what will happen when you try to retrieve or remove it? Can two threads accessing the same object with synchronized methods cause a deadlock? Explain a scenario. Given a linked list, how would you detect a cycle without using extra space? What’s the time complexity? If you have a nested loop where the inner loop doubles the index each time, what is the overall time complexity? How does parallelStream() differ from stream() internally, and when can it actually degrade performance? If you override equals() in a class but forget to override hashCode(), what issues could occur in collections?