Frequently Asked Java Interview Questions

Basics::

1. What are OOPS concepts and explain them?
2. What is Inheritance?
3. How and why you have implemented Inheritance in your project?
4. What is Abstraction?
5. How and why you have implemented Abstraction in your project?
6. What is Encapsulation?
7. What is Access Specifier and explain them?
8. What is Access Modifiers and explain them?

Exceptions::

1. What is Exception and explain its different types?
2. What kind of exceptions you have encountered in your project?
3. Why finally block is required when we can close resources after catch block?
4. str="java"; str.substring(7); Do we get any exception in above code if yes what exception that will be?

String::

1. What is the advantage of String Pool?

HashMap::

1. What is HashMap?
2. Explain internal mechanism of HashMap?
3. Why you have used HashMap in your project if used?
4. Is HashMap allows duplicate keys if not what will happen if we try to insert duplicate value?
5. How can we allow HashMap to have duplicate keys in it?
6. Is HashMap allows duplicate values?
7. Is it possible to set initial size of HashMap if yes how?

List::

1. What is List?
2. Why you have used List in your project if used?
3. Is List allows duplicate values if yes then how can we stop it?
4. How can we make a Lis ready only without using any predefined functions?

JDBC::

1. Explain the steps to create JDBC connection?
2. From where we get SessionFactory in JDBC?

Features::

1. What are the features of Java 1.7?

Design Pattern::

1. Explain Singleton Design Pattern?
2. What will happen if we implement clone method in Singleton Design Pattern?

Unsorted::

1. What needs to be done to compare two objects?
2. What and why we required Generics?
3. What is Auto Boxing and Auto UnBoxing?