Java Programming - MCQ Practice Questions

What is the primary purpose of the Comparator interface in Collections Framework?

Which interface in Java Collections Framework is used to maintain insertion order while allowing duplicates?

What is the time complexity of get() operation in HashMap in average case?

Which collection class is synchronized and thread-safe by default?

What does the PriorityQueue in Java Collections Framework guarantee?

Consider: List<String> list = new ArrayList<>(); list.add("Java"); list.add("Python"); What will list.get(1) return?

Which method returns true if the map contains the specified value?

Which of the following collections maintains insertion order while allowing fast random access?

What will be the output of the following code? Set<Integer> set = new TreeSet<>(); set.add(5); set.add(2); set.add(8); set.add(2); System.out.println(set.size());

What will happen when you execute: Map<String, String> map = new HashMap<>(); map.put("key", null); System.out.println(map.get("key"));

Which interface must be implemented to create a thread in Java?

Which method is used to stop a thread in Java?

Which method is called to make a thread wait until another thread completes?

Which of the following is a valid way to create a thread in Java?

In Java multithreading, which method is used to pause the execution of a thread for a specified number of milliseconds without releasing locks?

What is the primary purpose of the synchronized keyword in Java?

Which of the following statements about the notify() method is correct?

Which exception is thrown when a thread is interrupted while waiting?

What is the return type of the join() method in Java threading?

Which of the following best describes the purpose of the Runnable interface in Java?