Java Interview Questions (Core Java Coding, Java Oops, Multithreading)

In this blog for Java interview question, we are going to list the important questions that are frequently asked by the interviewer and taken as important part of the interview process. You would be surprised knowing that Java is used worldwide by more than 10 million developers to develop more robust apps and secure business solutions.

Java can also be used to develop apps for highly trending technologies like Big data and more. This is the reason why Java is used everywhere across different industry verticals successfully.

Java Interview Questions

With a careful research and experience of developers, we have compiled a list of top 50 questions that are frequently asked by interviewers and divided them into five major categories as given below –

  1. Core java interview questions
  2. Java collections interview questions
  3. Java coding interview questions
  4. Java programming interview questions
  5. Java oops interview questions

Let us dive deep into the topic and discuss the questions for each of the categories one by one…….

Core java interview questions

In the first section, we will give you top 10 core java interview questions for your reference that would help you in preparing for your interview more effectively.

  1. How can you differentiate the constructor and methods from each other? Is it possible to mark constructors as Final?
  2. Can you explain the significance the garbage collection in Java and how it can be used?
  3. What is synchronization in reference to the multithreading?
  4. How will you define the abstract classes in Java?
  5. Explain the different styles for thread implementation. Which one is more effective out of all?
  6. What is the significance of Public, Private, and the protected keywords in Java?
  7. What is Final Class in Java?
  8. Can you declare the main () method as private member in Java?
  9. When Java was started and what was the objective?
  10. Why Java is named as the platform independent language?

Java collections interview questions

The next popular section is Java collection. Let us discuss the top 10 interview questions to make the interview preparation little easier for you.

  1. How will you differentiate the Iterator and Enumeration?
  2. How can you explain the difference between List and Set?
  3. How collection and collections are different form each other in Java?
  4. Can you explain any advantage of Properties File?
  5. What do you mean by hash Code () method in Java programming language?
  6. How can you synchronize List, Map, or Set elements?
  7. Is there any advantage of generic collection?
  8. What is a Dictionary Class?
  9. How will you remove the duplicate values from the list of an Array?
  10. How can you synchronize the Array List in Java?

Java coding interview questions

This section is dedicated to experienced developers if you are showing some project work on your resume. Let us see how can you be evaluated on different parameters. Here is the list of top 10 questions for the section Java Coding interview.

  1. What is linked list in Java?
  2. How will you find the length of linked list?
  3. Can you check if the linked list has loop or not?
  4. How will you find the position of a particular element from the tail in the linked list?
  5. Can you convert a linked list to the Binary tree?
  6. Write a program for sorting the linked list.
  7. How will you find the smallest, largest, and the middle number in the list?
  8. Write a program to compare the two strings?
  9. Do you know how to merge the two lists successfully?
  10. How to reverse a linked list?

Java programming interview questions

Here, we will discuss some important questions related to Java programming that can be asked to freshers or experienced both.

  1. Why multiple inheritance is not supported in Java?
  2. How will you differentiate the String Buffer and String in Java?
  3. Can a top class be private or protected in Java programming language?
  4. What do you know about Java exception handling?
  5. Is there any difference between throw and throws exceptions in Java?
  6. Have you heard of finalize () method?
  7. Why is Java popular as platform independent language?
  8. What is inheritance in Java and its popular types?
  9. Explain the meaning of final keyword in Java
  10. What is the significance of super keyword for programmers?

Java oops interview questions

Java is an object-oriented programming language, so discussing the Java Oops interview questions is quite obvious. Here is the list of top 10 question to help your career.

  1. What Java is taken as the object-oriented programming language?
  2. What is method overloading in Java Oops?
  3. What is method overriding in Java Oops?
  4. Java is pure object oriented or there is some other aspect too?
  5. What is method hiding in Java programming language?
  6. Is it possible to overload the static method in Java?
  7. What is the usage of final modifier and its benefits?
  8. Is it possible to overload a private method in Java?
  9. Can we have a non-abstract method inside interface?
  10. What is the default method of Java 8?

By getting through all these questions carefully, you can always increase your chances of getting hired by top MNCs worldwide. We wish you luck for the next interview!