When you reach a few years of experience as a Java developer, you may want to apply for a senior role. However, there are a lot of steps you need to take before getting a job. One of those steps includes your job interview. During an interview, you will be asked questions to help your interviewers understand your skills, abilities, personality, and interests. The following are some of the expected technical interview questions and answers for a senior Java developer role.
Q1: What are the four platforms of the Java programming language? What are their differences?
Answer: The four platforms of the Java programming language are Java Platform, Standard Edition (Java SE), Java Platform, Enterprise Edition (Java EE), Java Platform, Micro Edition (Java ME), and Java FX.
Java SE is the base platform of the Java programming language. It contains all of the features programmers require to develop applications with this programming language. Java EE is a framework that allows developers to create large-scale and multi-tiered network applications. Java ME is a platform designed specifically for use in small-application development, like mobile apps. Finally, Java FX is a platform that allows developers to build applications for rich internet applications.
Q2: What is JVM and its benefits?
Answer: The Java Virtual Machine (JVM) is a virtual machine that runs bytecode instructions written in the Java programming language. The Java compiler then compiles these bytecodes into native code. After the bytecodes are compiled, the interpreter converts them to machine-understandable code. Essentially, it’s how developers run their Java programs. The JVM provides several benefits to application developers, including security, portability, and performance.
Q3: What are the features of the Java programming language?
Answer: Some of the main features of the Java programming language is that it’s a portable and platform-independent language. That means it works on any platform running the JVM. It also runs on most platforms, including desktops, servers, and mobile devices. In addition, Java is a programming language that allows you to create robust and secure applications.Â
Q4: How can we say that Java is object-oriented? Explain it briefly.
Answer: Java is considered to be an object-oriented programming language because it follows the principles of OOP. Object-oriented programming introduces seven fundamental concepts: objects, class, inheritance, polymorphism, abstraction, and encapsulation. However, we can’t say that Java is 100% object-oriented. This is because Java supports primitive data (boolean, byte, double, long, short, etc.) which are not objects.
Q5: What Is Spring, and how does it relate to Java?
Answer: Spring is an open-source development framework used for developing enterprise applications using Java. In simple words, Spring is a collection of reusable components that aid software engineers in building robust web applications. Java developers can easily integrate these components into their existing applications.
Q6: What is a Spring Bean in Java terms? What are the different scopes of Spring Beans?
Answer: Beans are the objects that form the backbone of a Spring application. The Spring’s IoC container manages them. These beans are created using the configuration metadata you provide to the container. Spring Beans should be instantiated, assembled, and managed by a Spring IoC container. There are five scopes defined in spring beans: singleton, prototype, request, session, and global session.
Q7: What is a Spring IoC container?
Answer: The Spring IoC container is responsible for managing Spring beans. It ensures that all the application components are properly configured before they’re used. This is done through the use of dependency injection (DI). As a result, the container ensures that only the correct classes and instances are used at runtime.
Q8: What do you mean by the term “Dependency Injection”?
Answer: Dependency injection means that instead of creating new instances of dependencies, you ask to have the dependency injected for you. So rather than having your own copies of the objects you need, you let Spring manage them. This makes testing easier, as you don’t need to spend a lot of time setting up the environment correctly. You just create the test case and pass in the necessary dependencies.
Q9: What are constructors in Java? Explain the types of constructors.
Answer: In Java, a constructor is a method that initializes the state of an object. Constructors are usually called automatically when an instance of a class is created. There are three types of constructors in Java. The first is the non-argument constructor. It has no arguments and is used when you don’t define parameters. The second type is the parameterized constructor. It takes arguments and can initialize the instance variables with the provided values. The third type is the default constructor. Java automatically creates default constructors if it is not explicitly defined.
Q10: What are method references?
Answer: Method references are added in Java 8 to help developers create simple lambda expressions. The four method references are:
- Static methods.
- Instance methods of particular objects.
- Instance methods of an arbitrary object of a particular type.
- Constructor.
A Java developer can write clear and concise code when using method references.
Final Words
In addition to typical interview questions, interviews for a Java developer role will typically include questions like the ones above. Try to answer them thoroughly and clearly. With practice and some confidence, you can ace these interviews. Good luck!
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