22 Java Interview Questions for Those With 5 Years of Experience
By Indeed Editorial Team
Updated June 14, 2022 | Published February 8, 2021
Updated June 14, 2022
Published February 8, 2021
Java runs on billions of devices, making it one of the most widely used programming languages. Software developers, app designers and programmers use this programming language every day. If you have an upcoming interview in software or app development, studying Java questions can help you feel more confident. In this article, we review the best ways to answer 22 senior-level Java interview questions.
22 Java interview questions for five years' experience
Here are 22 Java questions and answers to help you prepare for your next interview:
1. What are the most important features of Java 8?
Many organizations prefer to use the 2014 release, Java 8, and not upgrade to a newer version as it is free for commercial use. Explain the features of this release that you find most useful.
Example answer: "I started my career in 2016, so I am very familiar with Java 8. The most important features of that release are the static methods and the functional interfaces. Adding functional interfaces to the object-oriented interfaces makes programming less complicated and more efficient."
2. Are you familiar with the latest Java release?
Java regularly releases updates to help functionality and ease of use. You should be familiar with these updates, including the latest one, and be ready to discuss the benefits or drawbacks of various versions.
Example answer: "I am an app developer, so I use Java 14 every day for work. The garbage collection and switch expressions are far better than other releases, and I really like having access to the JRF event streaming tool."
3. Can you explain what a Java class is?
A Java developer needs to know the core elements of the language. Be concise when answering to show your understanding. An interviewer is likely to use a question like this to transition to more complex questions.
Example answer: "Class represents a category for objects with similar methods or properties. It's used as a blueprint for design in any object-oriented programming."
4. What are some common classes in Java?
This is also a question that reveals your core knowledge of Java. Be concise and use simple language to show you have a thorough understanding of the language. Prepare a detailed response in the event that the hiring manager wants to know how you use each class in your work.
Example answer: "There are so many classes in Java. A few essentials are final, static, concrete, abstract, inner and POJO. Would you like me to elaborate on how I use these in app development?"
5. If you were training someone in Java, what would you tell them about wrapper classes?
Give an accurate answer that shows your technical knowledge of Java and also your interpersonal skills and ability to share information with others.
Example answer: "If I were training someone in wrapper classes, I would first make sure they understood all eight primitive types and how they can use them. I think the most important thing to convey is that assigning a wrapper class is final and immutable. Knowing this will save that person a lot of time."
6. Can you tell me what the four access modifiers are in Java and explain why we use them?
When answering this question, list all four access modifiers and show your understanding by giving a clear and efficient description of why programmers use them.
Example answer: "The four access modifiers are public, private, protected and default. We use them to determine who has access to information or keywords within a class."
7. What is the benefit of a multi-catch block in Java?
Multi-catch block is an improvement that came with the Java 7 release. Be ready to answer questions on this critical part of the programming language.
Example answer: "With multi-catch blocks, code is shorter. This makes code easier to create and easier for others to interpret. Also, making exception parameters final is less complex with this format."
8. Can you describe the difference between JDK and JVM?
People use the Java Development Kit (JDK) to design software and apps, and Java Virtual Machine (JVM) is what allows them to run. Clearly explain this difference when answering this question.
Example answer: "JDK is a software development kit, and JVM is what allows Java to run on a device. Without JVM, the apps I create using the tools in JDK wouldn't work on people's phones or tablets."
9. Can you tell explain the difference between path and classpath variables?
This is a question regarding Java's architecture. Answer this question by describing how these variables differ.
Example answer: "Classpath is specific to Java executables, and it's used to locate class files, whereas path exists in an operating system and is used to locate executables."
10. What is a final class in Java?
This is a question regarding Java's architecture. Answer it by defining what final means and explaining why it is useful.
Example answer: "This is a designation that says a class cannot be extended or overridden by a subclass. Declaring a class final helps prevent inheritance and keeps information secure."
11. If an intern asked you what static meant in Java, what would you say? Can classes be declared static?
This question assesses your knowledge of Java and your ability to lead and coach, which are valuable skills on a team. Take the opportunity to share a personal experience and show how it makes you a better teammate.
Example answer: "I had the greatest mentor my internship senior year. She really showed me how to apply what I was learning in school in the real world. If I was helping an intern, I would explain that static simply means that one thing belongs to another. You can have static blocks, static methods and static classes. I would show that person how it's done. Seeing firsthand that top-level classes cannot be declared static—but inner classes can—will help the information stick."
12. Can you explain what platform independence is?
Java is designed to be platform-independent. If an interviewer asks this question, briefly explain what this means.
Example answer: "Platform independence is when you design a program that can run on any operating system. It makes things easier to use and market. This is why I think Java is superior to other programming languages."
13. What is your favorite aspect of Java?
This question assesses Java knowledge, but it is also an opportunity to share a bit more about your personality or experience.
Example answer: "There are so many things to love about Java, but I think my favorite thing is the community. People use Java all over the world, and many of them are doing really innovative things with it. I just really like knowing this programming language because it allows me to interact with a lot of people and get insight and inspiration for different ways to use it."
14. What is the biggest challenge you have ever had with Java?
Remember to stay positive in answering this type of question. Also, make sure that the example challenge you discuss is one that you have overcome and grown from.
Example answer: "When I first started coding, I was so excited about turning my ideas into usable programs. I was pretty successful in doing that, but I struggled with creating clean code. My internship mentor showed me how important it is that your code is clean and easy to read. In the long run, clean code allows for more team collaboration, which ultimately leads to better products."
15. What do you think the purpose is behind string being immutable?
This question means to assess your understanding of code logic and reasoning.
Example answer: "Making string immutable makes the string thread-safe. If string were somehow not immutable, then changing one reference would alter the value of other references."
16. Can you explain serialization and deserialization?
A Java developer needs to know to handle the input and output of information. Explain how these terms relate to stream handling in Java.
Example answer: "Serialization and deserialization are crucial to stream handling in Java. When you serialize an object in Java, you convert it to byte stream so it can be saved or relocated to another device. Deserializing simply undoes that process."
17. If a colleague with less Java experience was having trouble serializing a class, what would you do?
This is another question that checks both your ability to work as a part of a team and your Java knowledge. Use this as an opportunity to highlight your expertise in both areas.
Example answer: "If a colleague was having a hard time with serializing class, I would make sure that they knew how to implement Java io. serializable interface. If they already know how to do that, then I would double-check that they were trying to serialize non-static data members. Static data members aren't saved using serialization—and I've seen many people make that mistake."
18. Can you describe what an interface is?
A Java developer needs to know the core elements of the language. Define this term clearly to show your understanding.
Example answer: "An interface is similar to class because it is a reference type and it defines methods. It is distinct from class because it does not implement methods."
19. What makes an interface different from an abstract class?
This is a common interview question for software developers, as abstract classes and interfaces are essential in object-oriented programming. Study the definitions of both and be ready to explain how they differ.
Example answer: "There are a few differences between an interface and an abstract class. The most distinguishing feature is that an abstract class can have method implementation and interfaces cannot. Abstract classes can also implement an interface."
20. How does a local variable differ from an instance variable?
Provide a concise answer that explains how these terms differ.
Example answer: "When programming, you declare local variables within a method. Instance variables are declared within class—not method."
21. What is a ternary operator?
Give a simple answer that explains what this term means and what its function is.
Example answer: "A ternary operator is a conditional operator in Java. It decides which values are assigned to a variable."
22. What is the most impressive thing you have ever used Java to do?
With this question, the interviewer wants to see if your innovation matches your technical knowledge. Explain the project and be prepared to give more technical information about how you made the project a success. If possible, include the project in your portfolio so the hiring manager can see it.
Example answer: "I've done a lot of things using Java that excite me. Recently, I created a puppy mind-reading app. The user uploads information about their dog, and the app designs a voice and personality that matches their pet. So, when you turn the camera toward your dog, the app will speak for them. It's really cute, and it was a super fun project for me to work on."
Tips for preparing for a Java interview
Here are 3 tips to consider when preparing for an interview for a career using Java:
Engage the Java community. There are many social media groups and internet threads for people to discuss how they are using Java. Consult these groups for ideas and questions.
Attend a webinar. Review the most up-to-date practices and Java releases by attending a webinar or online refresher. There are many free or low-cost courses available where you can learn new skills and find new uses for Java in your professional life.
Do a mock interview. Use a mirror, voice recorder or friend to practice answering questions about your technical skills using Java and your related experiences. Speaking your ideas aloud is likely to help you feel confident and ready for your interview.
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