Java interview questions and answers for 2022

It takes some grind to ace a Java interview. So, how will you swim through your advanced java interview questions? Or, how will you find the bright minds who can answer core java interview questions like they were primary math questions? Whether you are an experienced Java developer or a recruiter seeking the best Java developers, we encourage you to go through the following docket of Java interview questions. We hope it will help you find your dream job or dream candidate.

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If you are here, it means you either have a Java interview that requires knowledge of Java 8 interview questions or you are looking to interview the best Java developers. Java, as a programming language, is in very high demand, with close to 10 million developers using Java to power more than 15 billion devices worldwide. As a Java developer or as a recruiter looking for Java developers, you will find this list of Java interview questions nifty.

You can use the advanced Java interview questions here to answer other similar questions or make similar questions for your candidates.

Java interview questions and answers


List some important features of Java.

One of the commonly asked Java coding interview questions is about the features of the language. Some important Java features are as follows:

Ease of learning: Java is considered to be an easy-to-learn and understand language.

Security: Java is a secure language. The applications developed using this language are virus and tamper-proof.

OOP: OOP means Object-Oriented Programming Language. While Java is not considered to be purely object-oriented, the inclusion of features such as data abstraction, inheritance, and data-encapsulation, makes Java an object-oriented programming language. Thus, as such, everything in Java is considered an object.

Independent Platform: This is an important Java feature. Java does not depend on any specific platform and as long as the system has JRE installed, Java bytecode will be interpreted.


Name the types of memory allocations in Java.

Another popular Java interview question is about memory allocation. Five important types of memory allocations in Java are - Heap memory, Class memory, Native method stock memory, Stack memory, and Program-counter memory.


As a language, Java is considered platform-independent. Why?

Java is considered to be platform-independent because it does not depend on any hardware or software. When the Java programmer compiles Java code, the compiler converts the code into bytecode that can be run on different platforms. The only constraint is that the platform must have JRE (runtime environment) or Java Virtual Machine (JVM) installed on it. Answering this Java interview question can help the interviewer understand your depth of experience.


What is data-encapsulation in Java?

Data-encapsulation in Java is the process of hiding the variables (data) and the code applied to the data in a single unit. It is a significant feature of object-oriented programming. This helps Java developers to isolate different objects from each other and to create modules for each. By this, all objects would have their own behaviors, attributes, and functions. It prevents data or object mixing, hides data, enhances security.


What are wrapper classes in Java?

Java, as a programming language, supports primitive data types. Wrapper classes help convert these primitive data types into objects or reference types and vice versa. Thus, the wrapper classes are so named because they ‘wrap’ these data types into identifiable objects of the specific data classes the primitive data types belong to. This Java interview question can help the interviewer assess whether you are comfortable using both old and new data types.


What are constructors in Java?

In Java, constructors can be understood as a block of codes applied to an object to initialize it. It can be understood as a special method for initializing an object. Constructors are called when a class instance is created such as creating an object using the new() keyword. When a class does not contain a constructor, a default constructor, provided by the Java compiler, is automatically called.

There are two types of Java constructors - default and parameterized. When no parameters are defined, the constructor is called a default constructor. When specific parameters are defined for a constructor, it is called a parameterized constructor. While you may be using the Java programming language for some time, this Java interview question shows the interviewer that you know the technicalities too.


Why is Java not considered to be purely object-oriented?

Java supports primitive data types such as boolean, int, byte, long, float, etc. An object-oriented language must only support objects. However, the primitive data types are not objects, hence Java is not considered to be purely object-oriented.


Does Java use pointers? If not, why?

No, unlike C++, Java doesn’t use pointers. Java’s main focus is simplicity. The use of pointers complicates the process, especially for new java programmers. The use of pointers can also lead to possible errors. Moreover, pointers grant direct access to memory and thus, compromise security. By excluding pointers from Java, a certain amount of abstraction is achieved. Java has automatic Garbage Collectors, the use of pointers can slow down the garbage collection process. This advanced Java interview question deals with the intricacies of the language and answering it can help set you apart from other candidates.


Can you override static methods in Java?

No. While it is possible to hide the parent static method with a static method of the same signature class, this is not called overriding in the strict sense. This is because, during the run-time, no polymorphism can take place.


What do you understand about ClassLoader in Java?

ClassLoader is an integral element of the JRE (Java Runtime Environment). The function of the ClassLoader is to dynamically load Java classes directly to the JVM (Java Virtual Machine) during program execution, without notifying the Java run time system. The file to be executed is first loaded by ClassLoaders. Bootstrap, Extension, and Application are the ClassLoaders in Java. This is an advanced Java interview question and answering it can establish your expertise.


What is the JIT compiler in Java?

With the help of JIT or a Just-in-time compiler, Java programmers can enhance the Java applications’ performance. This is achieved in a runtime environment by compiling bytecode to the code of the native machine. As a result, the compilation time for running the code reduces. In essence, the JIT compiler translates the source code to a code that can be executed by the machine.

Java programs contain machine-neutral bytecodes that can run on any machine with JVM. When a Java program is run, it accesses the class files, interprets the bytecode, and performs the relevant computation. However, during the processing, extra memory and processor are used which compromise the speed. With the help of the JIT compiler, the speed and performance of the program can be improved.


What are the prospects of session management in servlets?

A session is any ongoing random conversation between a client and the server. The communication between the two is composed of requests and responses from both sides. There are several ways of managing a session. Applying cookies, using session management API, authenticating the user, hidden fields in HTML, and rewriting URL are some ways of session management. However, the most common way of managing a session is using a session ID when the communication between a client and the server takes place. This Java interview question shows your application orientation to the client.

Wrapping up

The above list of Java interview questions will help you get a hang of the technical part of the interview. However, aside from the technical questions, you must also prepare for the generic ones dealing with your soft skills like communication, teamwork, time management, and project management. As a recruiter as well, apart from the core Java interview questions you should also quiz your candidates on their soft skills. If you feel confident of your knowledge of Java programming interview questions, we encourage you to take the Turing Java Test to find out if you are among the best Java developers. If you are a recruiter looking for the best Java developers, contact Turing.

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