Java Programming - MCQ Practice Questions
Java interviews and campus tests lean heavily on object oriented behaviour rather than API recall. This set covers inheritance and polymorphism, interfaces and abstract classes, the collections framework, exception handling, multithreading, string handling, and JVM basics such as garbage collection. Output based questions are included because they expose the gaps that theory questions hide.
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Which collection implementation is best for frequent insertions and deletions at both ends?
What is the purpose of the fail-fast iterator in Collections?
Consider a TreeMap with Integer keys. What will headMap(10) return?
Which collection interface guarantees that elements are stored in a sorted order with no duplicates?
Which collection would you use if you need to maintain a sorted order of elements and also need O(log n) insertion/deletion time complexity?
Which of the following statements is true about PriorityQueue?
What is the time complexity of get() operation on a LinkedHashMap with n elements?
Which collection interface should be used if you need both key-value pairing and need to iterate in the order of keys' natural ordering?
What will be printed? Queue<Integer> queue = new LinkedList<>(); queue.add(10); queue.add(20); queue.add(30); System.out.println(queue.poll()); System.out.println(queue.peek());