Java Developer Interview Questions

Position Summary

Java developers possess expert knowledge of one of the most diverse programming languages available. It can be used for many applications, from creating and building web-based applications to designing sophisticated desktop applications.

Java developers are in high demand due to their command of Java. They can use their coding skills across many platforms to integrate Java into business applications, software, and websites, and to troubleshoot errors.

Responsibilities

Java developer responsibilities may include:

Designing Java application phases
Developing application code
Developing technical designs for applications and software
Providing troubleshooting services as needed
Testing out code across various devices to ensure quality across all platforms

Skills

Many of the applications used daily are built from Java. In order to provide optimal user experience, skilled Java developers will:

Utilize creative thinking to problem solve
Think quickly to solve problems as they arise
Communicate clearly with their team
Use customer feedback to improve product quality
Stay on top of industry trends

Qualifications

Many entry-level positions will prefer applicants with a bachelor’s degree in computer science or a related field. However, candidates without formal education can still find employment if they have relevant experience and demonstrate an expert understanding of the code.

If you’re getting ready to interview for a position as a Java developer, you can prepare by researching the company as much as possible. Learn about the 9 things you should research before an interview.

Salary

Salaries for Java developers range between $66K and $116K with the median being $94K.

Factors impacting the salary you receive as an Java developer include:

Degrees (associate's or equivalent technical training, bachelor's, master's, etc.)
Years of Experience
Location
Reporting Structure (seniority of the manager you report to and number of direct reports)
Level of Performance - exceeding expectations

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JAVA Developer Interview Questions

Question: Can you provide an overview of the critical features of the Java programming language?

Explanation: This is an opening question which the interviewer will ask to start the conversation, learn more about your background, and collect information they can use for subsequent questions.

Example: “Java has become the world’s most popular programming language because of its many features. These include its simplicity and ease of programming, the fact that it is object oriented, its portability across platforms, the built-in security features, its robustness due to strong memory management, and its ability to create distributed applications.”

Question: Please define access modifiers and describe how they are used in Java.

Explanation: This is a technical question. You can recognize technical questions due to their structure. They first ask you to define a term and then describe how it is used for the function about which the interviewer is asking you.

Example: “Access modifiers are keywords that establish accessibility to methods, classes, and other objects. There are four types, including public, protected, default, and private. Each of these describes how the members within Java can be accessed and by whom.”

Question: What is the JDBC API, and how is it used within Java?

Explanation: The interviewer is asking you another technical question. Technical questions are best answered directly and briefly. The interviewer will ask a follow-up question if they need additional information or want to explore the topic in more depth.

Example: “Java database connectivity or JDBC API enables Java to work with relational databases. This is part of the java.sql and javax.sql packages. Its function is to run SQL worries, and stored procedures were then the relational database.”

Question: Can you briefly describe the different types of JDBC drivers and how they relate to the JDBC API?

Explanation: This is a follow-up to the previous question. Any time you provide an answer to the interviewer, you can anticipate a follow-up question. Keeping your answers brief and to the point will enable the interviewer to move on to the next question or explore the topic in more depth by asking a follow-up question.

Example: “The JDBC drivers actually do the work such as issuing queries and extracting data once the JDBC API has connected to a relational database. There are four types of JDBC drivers available. These include the ODBC driver, the native API partly Java technology-enabled driver, the pure Java driver for database middleware, and the direct-to-database pure Java driver. Each of these functions differently when connecting to and extracting data from relational databases.”

Question: How do path and classpath variables differ from each other?

Explanation: Another format a technical question can take is to provide you with two terms and ask you the difference between them. The best way to structure your answer to this type of question is to define each term and then describe their function and how they differ. An alternate form of this question may ask how the two terms relate to each other.

Example: “Both path and classpath variables allow Java to locate executables within the code. Path is an environmental variable and contains the directory location of executables. Classpath is specific to the Java programming language and is used for locating class files called by Java executables. These have included ZIP files, JAR files, and others.”

Question: There is some confusion as to whether Java is pass by or pass by reference. What do you believe, and why?

Explanation: While this is a technical question, it also asks for your opinion. Sometimes, questions asking for opinions have no right answer. The interviewer is merely trying to understand where you stand on a specific issue. However, in this question, there is a correct answer. Knowing it will distinguish you as being qualified for this position.

Example: “I have heard people describe Java as being either pass by reference or pass by value. According to the Java Spec, Java is pass by value. This relates to the variable paths and method calling.”

Question: How does Java use the final keyword?

Explanation: This is an operational question. Operational questions help the interviewer understand how you go about performing a specific task required by this position. Like technical questions, operational questions are best answered directly and succinctly. The interviewer will ask you a follow-up question if they require additional details.

Example: “Java uses the final keyword with a class to make sure the other classes can’t extend it. It also ensures that different methods cannot be overridden by any child class. Finally, it will classify variables as final so that it can only be assigned once.”

Question: What is Enum, and in what version of Java was it introduced?

Explanation: You probably already recognized this is a technical question. As a Java developer, the majority of your interview will consist of technical and operational questions. You should continue to answer these directly and concisely. Keep in mind that every answer may generate a follow-up question.

Example: “Enum is a type whose field consists of a fixed set of constants. It was first introduced in Java version 1.5. A Java developer will establish the field and then define the constants which it can contain. These constants are final and implicitly.”

Question: How is composition used while programming in Java?

Explanation: This is yet another technical question. As the interview progresses, the technical questions will become more specific and more difficult. This indicates the interviewer is gaining confidence in your capabilities and is willing to explore more complex topics. Continue to answer these more complicated technical questions the same way you did the easier ones.

Example: “Composition is a design technique used in Java in several ways. It is used to implement a relationship between classes and also for code reuse. It achieves this by using variables that refer to different objects. Its benefit is that it provides control over the visibility of objects and client classes when the code is reused.”

Question: What function does the Java Reflection API perform?

Explanation: This is a hybrid technical and operational question. First, it asks you to define a term and then discuss how it is used to perform a function. The best way to prepare for this type of question is first to review the job description and identify the requirements for the position. You should then research the company to better understand the type of programs they develop, the code they use, and their programming methodologies. Finally, before the interview, take some time to review standard Java development terms, processes, and methodologies. The last step is to practice questions like these.

Example: “The Java Reflection API gives the developer the ability to view and change the behavior of any application while it is running. It allows you to inspect a variety of objects within Java and obtain their methods and details.”

Additional JAVA Developer Interview Questions

How would you scale access to a system such as Twitter?
How would you handle the launch of a billing system?
Have you ever gotten into a disagreement with a team member? How was it handled?
Can you describe a Java tree and why it is important to balance them?
What might cause a memory leak, and how would it be fixed?

A word of warning when using question lists.

Question lists offer a convenient way to start practicing for your interview. Unfortunately, they do little to recreate actual interview pressure. In a real interview you’ll never know what’s coming, and that’s what makes interviews so stressful.

Go beyond question lists using interview simulators.

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