Java Collections Framework Interview Questions

    Question 1: JAVA - Collection Interface

    Which of the following is the root interface of the Java Collections Framework?

    Question 2: JAVA - List Characteristics

    Which statement about `List` is correct?

    Question 3: JAVA - Set Characteristics

    Which statement about `Set` is true?

    Question 4: JAVA - Map Basics

    Which statement is correct about `Map`?

    Question 5: JAVA - ArrayList Example

    What will this code print?

    import java.util.*;
class Test {
    public static void main(String[] args) {
        List<String> list = new ArrayList<>();
        list.add("A");
        list.add("B");
        list.add("A");
        System.out.println(list);
    }
}

    Question 6: JAVA - HashSet Example

    What will this code print?

    import java.util.*;
class Test {
    public static void main(String[] args) {
        Set<Integer> set = new HashSet<>();
        set.add(1);
        set.add(2);
        set.add(1);
        System.out.println(set);
    }
}

    Question 7: JAVA - HashMap Example

    What will this code print?

    import java.util.*;
class Test {
    public static void main(String[] args) {
        Map<Integer, String> map = new HashMap<>();
        map.put(1, "Java");
        map.put(2, "Python");
        map.put(1, "C++");
        System.out.println(map);
    }
}

    Question 8: JAVA - Iterator

    Which method of `Iterator` is used to remove an element during iteration?

    Question 9: JAVA - Fail-Fast Iterator

    Which collections use fail-fast iterators?

    Question 10: JAVA - Queue Interface

    Which method of `Queue` retrieves and removes the head of the queue, or returns `null` if empty?