Java Programming - MCQ Practice Questions

Which keyword is used to prevent a class from being subclassed in Java?

Which interface does HashMap implement in Java Collections Framework?

What is the time complexity of get() method in HashMap?

Which of the following collections maintains insertion order?

What is the difference between ArrayList and LinkedList?

Which collection does NOT allow duplicate elements?

What is the difference between TreeSet and HashSet in sorting?

Which method in Set collection prevents duplicate insertion by returning false?

What is the output of LinkedHashMap iteration in the following code? LinkedHashMap<String, Integer> map = new LinkedHashMap<>(); map.put("A", 1); map.put("B", 2); map.put("C", 3); for(String key : map.keySet()) System.out.print(key);

Which collection class implements NavigableMap interface?

In the context of streams and collections, which method returns a Sequential Stream in Java 8+?

Which Collection method was introduced in Java 9 to create immutable collections?

Which of the following Collection interfaces does NOT support duplicate elements?

What is the default initial capacity of a HashMap in Java?

Which collection class is synchronized by default?

What does the poll() method return when called on an empty Queue?

Which of the following correctly represents the hierarchy of Collection framework?

Which interface in Java Collections Framework does not allow duplicate elements?

What is the underlying data structure of HashMap in Java?

Which of the following maintains insertion order in Java?