Top 100+ Java coding interview questions

Java is a booming technology across the world, and it is a simple and robust language to code and even learn. Code reusability is one of the prominent features of Java which is not possible with the C language. Inheritance is an important concept that is introduced in Java for code reusability.

Java is used everywhere as it is open-source software, and it also provides a platform for many users to perform a specific task effectively. According to Oracle 3 billion devices run on Java, 3 billion devices run on Java. Some of the applications where Java is used are Access control systems, Automobiles, IoT gateways, optical sensors, and many more.

If you are aspiring to start your career in the field of Java as a developer, then you are in the right place. These days, cracking the Java interview has become more critical due to increased complexity in the interview process.

We have gathered a bunch of Frequently asked Java Interview Questions 2022 over here. These questions would help you stand apart from the crowd and crack the interview very easily. So, let’s get started with the interview questions.

50 Top Core Java Interview Questions and Answers

To make it easier for you, we have categorized the set of core Java interview questions into three levels, namely Basic, Intermediate, and Advanced. Let us begin with the basic level.

Basic Java Interview Questions/Java interview questions for freshers

Answer: Java is a general-purpose, high-level, object-oriented programming language that works on the principle “write once and run anywhere.” James Gosling developed it in 1991 at Sun Microsystems, and later, Oracle Corporation later bought Sun Microsystems.

Read more about the Java programming language here .

Answer: When Oracle bought Java, they gave their own definition to it and released the Java Standard Edition, which is commonly known as core Java and is the parent of all the Java versions. It deals with the basic type and Object of Java Programming.

Answer: Java SE 17 is the latest version of Java that comes with Long Term Support (LTS). The next Java versions tentative release dates are

Java Versions Release Date
Java SE 18 March 2022
Java SE 19 September 2022
Java SE 20 March 2023
Java SE 21 (LTS) September 2023

Answer: JVM is an acronym for Java Virtual Machine . JVM is one of the essential parts of the Java Runtime Environment (JRE). It is the one that calls the Main method of Java code.

Answer: Bytecode is a compiled format of a Java program. Classloader loads the bytecode into a java runtime environment where the JIT compiler converts bytecode into machine-dependent code.

Answer: The flow of execution is referred to as a thread. The main function is present in every java program. Is also a thread. Java Virtual Machine (JVM) is responsible for creating this main thread. The user can create their own thread by extending the thread class.

Answer: Main is the entry point of the program; hence it is declared as static. For calling the static method, we never need an object of a class.

Answer: If superclass and subclass both have the same method as well as the variable name, we use the super keyword to access superclass variables. The super refers to the superclass, and the super keyword can access the superclass variables when the super class has no constructor.

85 java interview questions

Answer: A default constructor of the superclass will get invoked when a subclass has only parameterized constructor, and the superclass does not have any matching constructor. If the superclass has parameterized constructor and the subclass wants to use that constructor, then we must write the “super” keyword to pass parameters in the superclass constructor. The super keyword must be written in the very first line in the constructor of the subclass.

Answer: Access modifier is also known as access specifiers. Access modifiers in Java have clarified the classes that can access a given class and its fields, constructors, and methods.

  • Public: A type of access modifier. We can declare a class, method, and variable as public. When we declare a class, method, or variable as public, they are accessible from any class.
  • Static : It is a keyword in Java that identifies a class as static. We can access a static class without creating the instance of the same.
  • Void : Void is a return type of method that will not return any value.
  • Main : It refers to a method that is searched by JVM as the starting point for an application with a particular signature only.
  • String args[]: It is a parameter that is passed to the main method.
  • Answer: In Java, constructors are similar to methods. A constructor is called when an instance of an object is created. The name of the constructor is the same as the name of the class having it. There is no return type of a constructor, not even void. If we don’t create an explicit constructor in our class, the Java compiler creates it by default.

    Answer: A wrapper class is a class that converts Java primitive data types into reference-type objects. It “wraps” the primitive data type into an object of that class, and therefore, we refer to it as a wrapper class.

    Answer: Local variables are defined inside methods and constructors. On the other hand, instance variables are those variables that are present within a class but outside any method.

    Answer: Java is a statically typed language because the type of the variable is known at the compile time.

    Answer: JRE is the abbreviation of Java Runtime Environment. It is an environment in which bytecode runs. In other words, a JRE is a software package that has everything to run a Java program.

    Question 2 : Write a java program to check if two Strings are anagram in java?

    Solution: Two string are anagrams if they have same characters but in different order. For example: Angel and Angle are anagrams There are few ways to check if Strings are anagrams. Some of them are:

  • Using String methods
  • Using array.sort
  • Check solution at

    Explain in brief the history of Java?

    In the year 1991, a small group of engineers called ‘Green Team’ led by James Gosling, worked a lot and introduced a new programming language called “Java”. This language is created in such a way that it is going to revolutionize the world.

    In today’s World, Java is not only invading the internet, but also it is an invisible force behind many of the operations, devices, and applications.

    FAQ

    What are the basic questions asked in Java interview?

    Java Interview Questions for Freshers
    • What are the differences between C++ and Java? …
    • List the features of the Java Programming language? …
    • What do you get in the Java download file? …
    • What is a ClassLoader? …
    • What are the Memory Allocations available in JavaJava? …
    • What are the differences between Heap and Stack Memory in Java?

    What is Java interview questions for freshers?

    Java interview questions for 2 years experience
    • Can we override static method in java?
    • Can you overload main method in java?
    • Can we override private methods in java?
    • What is the base class for all the classes?
    • Can you list down some of important method from object class?

    What are the advance Java interview questions?

    Here are the top 25 Java interview questions for freshers.
    • What are the key differences between C++ and Java? …
    • Explain the JVM architecture? …
    • What is the use of Classloader in Java? …
    • Which class is a superclass of all classes? …
    • What is the static keyword? …
    • What are finally and finalize in Java? …
    • What is Type casting in Java?

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