Java Interview Questions

Java Interview Questions

Aug 15, 2021ยท

2 min read

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Hello reader! The purpose of this article is to simply share some common java interview questions that I was asked in the past when going through job interviews with top financial firms. I hope that you'll find this useful.

  • What is a class
  • What is an object
  • Object VS class
  • Method overloading
  • Method overriding
  • Access modifiers (private, public, protected, default)
  • Difference between method overloading VS method overriding
  • Object-Oriented Programming: inheritance, polymorphism, abstraction and encapsulation.
  • Aggregation and association.
  • Dynamic binding (linked to abstraction)
  • Static keyword
  • Final keyword
  • Strings: talk about why they're immutable and what happens in the memory (stack and heap). String is a class.
  • Stringbuilder VS Stringbuffer
  • Interface: why it's used.
  • Can we have multiple inheritance? If not, why? What can we do instead?
  • Difference between abstract class and interface
  • Memory management: garbage collection, the types of garbage collectors
  • How does a hashmap work internally
  • Collections Framework
  • Exception handling: throw, throws keywords, what is a runtime exception.
  • Runtime Type Checking
  • Difference between the keywords final, finally, finalize
  • Try/Catch/ Finally block
  • Exception propagation
  • Multithreading: what is a thread, how to create a thread (Runnable interface OR Thread class)
  • Thread safety
  • Synchronize
  • Difference between a set and a list
  • Java 11 features
  • SOLID Principles
  • Test-Driven Development
  • Git commands
  • What does "unboxing"?
  • Is Java "pass-by-value" or "pass-by-reference"?
  • How do you return multiple values in Java?
  • What does "covariance" mean?

Related: Java Phone Interview Questions - Beginner Level

Good luck! ๐Ÿ€๐Ÿ€๐Ÿ€

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