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Senior Java Developer interview questions and answers

This Senior Java Developer interview profile brings together a snapshot of what to look for in candidates with a balanced sample of suitable interview questions. These are best suited as senior java developer interview questions, but can be modified for any member of a java development team. Similar job titles include Java Programmer, J2EE Developer, Java Application Developer, Java Integration Developer, Java Backend Developer.

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10 good senior java developer interview questions

  1. What does a Just in Time compiler have to offer? Do you know of any programming language runtimes that use one?
  2. How is preemptive threading model different from the cooperative threading model?
  3. What tools & practices would you consider necessary for a Continuous Delivery solution?
  4. What do you think makes a unit test good? What about functional ones?
  5. Do arguments in Java get passed by reference or by value?
  6. How is Java SE related to Java EE?
  7. What are the most important features introduced in Java 5, 7 and 8 respectively?
  8. What is the difference between HashMap, ConcurrentHashMap and Map returned by Collections.synchronizedMap?
  9. You want to synchronize 5 threads to start at the same time. Describe a solution.
  10. What do you know about the Java Scripting API? Can you think of a use case?

Here are 10 essential interview questions and sample answers to help identify the best candidates for this role.

1. What does a Just in Time compiler have to offer? Do you know of any programming language runtimes that use one?

This question assesses the candidate’s understanding of Just in Time compilation and its benefits.

Sample answer:

“A Just in Time (JIT) compiler converts bytecode into native machine code just before execution, improving performance. Java and .NET both use JIT compilers.”

2. How is preemptive threading model different from the cooperative threading model?

This question evaluates the candidate’s knowledge of threading models in programming.

Sample answer:

“In preemptive threading, the OS controls thread execution, while in cooperative threading, threads yield control to each other. Preemptive is generally more robust.”

3. What tools & practices would you consider necessary for a Continuous Delivery solution?

This question gauges the candidate’s familiarity with DevOps practices related to Java development.

Sample answer:

“Tools like Jenkins for automation, JUnit for testing, and Docker for containerization are essential. Practices include automated testing, code reviews, and frequent commits.”

4. What do you think makes a unit test good? What about functional ones?

This question assesses the candidate’s understanding of testing methodologies.

Sample answer:

“A good unit test is isolated, repeatable, and tests a single logical concept. Functional tests should cover user scenarios and may involve multiple units.”

5. Do arguments in Java get passed by reference or by value?

This question tests the candidate’s understanding of Java’s argument-passing mechanism.

Sample answer:

“In Java, primitive types are passed by value, and objects are passed by reference value, meaning the reference itself is passed by value.”

6. How is Java SE related to Java EE?

This question evaluates the candidate’s understanding of different Java platforms.

Sample answer:

“Java SE (Standard Edition) provides core Java features, while Java EE (Enterprise Edition) builds on SE and provides additional libraries for enterprise-level applications.”

7. What are the most important features introduced in Java 5, 7 and 8 respectively?

This question assesses the candidate’s knowledge of Java’s evolution.

Sample answer:

“Java 5 introduced generics, metadata, and enumerated types. Java 7 brought the try-with-resources statement. Java 8 added lambdas, streams, and the java.time package.”

8. What is the difference between HashMap, ConcurrentHashMap and Map returned by Collections.synchronizedMap?

This question tests the candidate’s understanding of Java’s collection framework.

Sample answer:

“HashMap is non-thread-safe, while ConcurrentHashMap is thread-safe and allows concurrent read and write. Collections.synchronizedMap provides a synchronized wrapper around a map.”

9. You want to synchronize 5 threads to start at the same time. Describe a solution.

This question evaluates the candidate’s knowledge of thread synchronization in Java.

Sample answer:

“You can use a CyclicBarrier with 5 parties to ensure that all threads start at the same time.”

10. What do you know about the Java Scripting API? Can you think of a use case?

This question assesses the candidate’s knowledge of Java’s capabilities for scripting languages.

Sample answer:

“The Java Scripting API allows you to integrate scripting languages like JavaScript into Java applications. A use case could be server-side data validation.”

What does a good senior java developer candidate look like?

A strong Senior Java Developer candidate will have an in-depth understanding of Java and its ecosystem, excellent problem-solving skills, and experience with best practices like testing and continuous delivery.



Senior Java Developer Interview Questions

In some respects even the most technical role demands qualities common to strong candidates for all positions: the willingness to learn; problem solving ability; qualified skills; passion for the job.

Even college performance, while it helps you to assess formal education, doesn’t give a complete picture. This is not to underplay the importance of a solid background in computer science. Some things to look for when asking these java senior developer interview questions:

• Understanding of basic algorithmic concepts
• Discuss basic algorithms, how would they find/think/sort
• Can they show a wider understanding of databases
• Do they have an approach to modeling?

Do they stay up to date with the latest developments? If so, how? Probe for their favorite technical books. Who are they following on Twitter, which blogs do they turn to?

Are they active on Github? Do they contribute to any open source software projects? Or take part in Hackathons. In short, how strong is their intellectual interest in their chosen field? How is this demonstrated? Ask for side projects (like game development). Committed, inquisitive candidates will stand out when asking technical interview questions.

Modify these java interview questions for the specific type of programmer you are looking for: Core Java, J2EE, application, integration or back end.

Modify and share this java developer job description to attract the most qualified candidates. Interview questions for similar roles include: Java Developer Questions and Java Software Engineer Questions.

Source Senior Java Developers using our Boolean search cheat sheets.

Computer Science questions

  • What does a Just in Time compiler have to offer? Do you know of any programming language runtimes that use one?
  • How is preemptive threading model different from the cooperative threading model?
  • What tools & practices would you consider necessary for a Continuous Delivery solution?
  • How is a code point related to a code unit in Unicode?
  • What do you think makes a unit test good? What about functional ones?

Role-specific questions

  • Do arguments in Java get passed by reference or by value?
  • Why would it be pointless for a static or final method to use dynamic binding?
  • How is Java SE related to Java EE?
  • How are Runtime exceptions different from Checked exceptions?
  • What are the most important features introduced in Java 5, 7 and 8 respectively?
  • Is ForkJoinPool introduced in Java 7 always a better alternative to ThreadPoolExecutor?
  • What is the difference between HashMap, ConcurrentHashMap and Map returned by Collections.synchronizedMap
  • You want to synchronize 5 threads to start at the same time. Describe a solution.
  • What is a weak reference and how could it be useful to us?
  • Choose a Java EE platform API and give a short description of it.
  • In a 3-tier application running a Java application server you notice freezes for several seconds during high load. What are the most likely reasons? How would you troubleshoot them?
  • Servlets 3.0 introduced async support. Describe a use case for it.
  • Why do you think lambda expressions are considered such a big thing for Java 8?
  • What do you know about the Java Scripting API? Can you think of a use case?
  • Is this possible in Java?
    A extends B, C

 

Source developer candidates using Workable’s Boolean search cheat sheets.

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