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06: HashMap & HashSet and how do they internally work? What is a hashing function?

Java equals vs hashCode

HashMap & HashSet are not only one of the frequently used data structures, but also one of the popular interview topics. Q1. How does a HashMap store data? A1. As key/value …


5 Java Object class methods interview questions & answers

Q1. What are the non-final methods in Java Object class, which are meant primarily for extension? A1. The non-final methods are equals( ), hashCode( ), toString( ), clone( ), and finalize( …


8 Java immutable objects interview questions & answers

Best Practice: “Classes should be immutable unless there’s a very good reason to make them mutable….If a class cannot be made immutable, limit its mutability as much as possible.” — by …


Java enum interview questions & answers

Covers the power of enumand 3 design patterns that can be applied with the help of enums. Q1. Why is it a best practice to use enums over static final int …


Java serialization, cloning, and casting interview Q&A

Q1. Which Java interface must be implemented by a class whose instances are transported via a Web service? a. Accessible b. BeanInfo c. Remote d. Serializable A1. Answer is “d”. Q2. …


Mocks, stubs, domain, and anemic objects interview Q&A

Q1. What are mock objects? A1. Mock objects are used in unit testing to ensure that your tests don’t fail due to volatility of the data changes. There are mocking frameworks …


Object equals Vs == and pass by reference Vs value

Q1. What is the difference between “==” and equals(..) method when comparing 2 objects?
A1.It is important to understand the difference between identity (i.e. ==) comparison, which is a shallow …


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