Here are some interview questions related to HashSet and HashMap:

Category : Java | Sub Category : Java Interview questions | By Prasad Bonam Last updated: 2023-08-03 13:43:46 Viewed : 323

Here are some interview questions related to HashSet and HashMap:

HashSet:

1. What is a HashSet in Java? How does it store elements internally?
2. What is the main difference between a HashSet and a List or an ArrayList?
3. How do you ensure that objects in a HashSet are unique? What methods are involved?
4. Can you have duplicate elements in a HashSet? If not, how does it handle duplicates?
5. How does the hashCode() method play a role in the functioning of HashSet?
6. Explain the significance of the equals() and hashCode() methods when using a HashSet.
7. How do you iterate through the elements of a HashSet?
8. Can you store null values in a HashSet?
9. What is the time complexity of basic operations (add, remove, contains) in a HashSet?

HashMap:

1. What is a HashMap in Java? How does it store key-value pairs internally?
2. How does a HashMap handle collisions when multiple keys have the same hash code?
3. What is the difference between HashMap and HashTable?
4. How do you retrieve a value from a HashMap using a key?
5. Can you store duplicate keys or values in a HashMap?
6. How does the hashCode() method influence the functioning of a HashMap?
7. What happens if you try to store a duplicate key-value pair in a HashMap?
8. How do you iterate through the key-value pairs in a HashMap?
9. Can you use custom objects as keys in a HashMap? What requirements should the key class meet?
10. What are the time complexities of basic operations (put, get, remove) in a HashMap?

General:

1. When would you choose to use a HashSet over a HashMap, and vice versa?
2. Under what circumstances would you consider using a ConcurrentHashMap instead of a regular HashMap?
3. What is the difference between fail-fast and fail-safe iterators in the context of HashMap and HashSet?
4. How does the initial capacity and load factor affect the performance of HashMap and HashSet?
5. How do you handle concurrency issues when using a HashMap or HashSet in a multi-threaded environment?

These questions cover both the basic concepts and some advanced topics related to HashSet and HashMap. Make sure to practice implementing and using these data structures to strengthen your understanding further. Good luck with your interviews!