JAVA Interview Questions for freshers

JAVA Interview Questions For Freshers In 2026

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Do you have the skills needed to crack a Java interview? We’re here to support you in strengthening and revising your Java fundamentals. Before diving in, let’s first understand what Java really is.

What is Java?

Java is a high-level programming language developed by James Gosling in 1982. It follows the principles of object-oriented programming (OOP) and is widely used for building large-scale, robust, and scalable applications.

This article covers a comprehensive range of Java interview topics, including Core Java, String Handling, Java 8, Multithreading, OOP concepts, Exception Handling, Collections, and commonly asked Java coding interview questions.

Reviewing these important questions will help you boost your confidence and improve your performance in Java interviews. The questions span basic, core, and advanced Java concepts, ensuring complete preparation.

So, let’s explore this extensive collection of Java Technical Interview Questions and Answers, organized into the following sections.

Java Interview Questions for Freshers In 2026

1. Why is Java considered a platform-independent language?

Java is designed to be independent of both hardware and operating systems. The Java compiler converts source code into bytecode, which is platform-independent. This bytecode can run on any system that has a Java Runtime Environment (JRE) installed.

2. Why is Java not a purely object-oriented language?

Java supports primitive data types such as byte, boolean, char, short, int, float, long, and double. Since these are not objects, Java cannot be classified as a purely object-oriented language.

3. Difference between Heap and Stack memory in Java and how Java uses them

Stack memory is allocated to each thread and has a fixed size. It stores method calls, local variables, and references.
Heap memory, on the other hand, is used for dynamic memory allocation and stores objects created at runtime.

In Java:

  • Local variables and method calls are stored in stack memory.
  • Objects are created in heap memory and referenced from the stack.
  • Methods like main() and variables declared inside it reside in the stack.
  • Objects such as an Integer array created during runtime are stored in the heap.

4. Can Java be called a completely object-oriented language?

Java can be considered object-oriented because everything is structured within classes and accessed via objects.
However, due to the presence of primitive data types, Java is not a purely object-oriented language. These primitives do not directly belong to object classes like Integer.

5. How is Java different from C++?

  • C++ is only a compiled language, while Java is both compiled and interpreted.
  • Java programs are platform-independent, whereas C++ programs run only on the platform they are compiled for.
  • C++ allows explicit use of pointers; Java does not.
  • C++ supports multiple inheritance, while Java avoids it to prevent ambiguity issues like the diamond problem.

6. Why does Java avoid using pointers?

Pointers are complex and can lead to unsafe memory access, especially for beginners. Java prioritizes simplicity and security, which is why it uses references instead of pointers. This abstraction also helps improve garbage collection efficiency and reduces memory-related errors.

7. Difference between instance variables and local variables

Instance variables are declared inside a class but outside methods. They represent object properties and are accessible to all methods of the class. Each object has its own copy, and changes affect only that instance.

Local variables are declared within methods, constructors, or blocks and are accessible only within that scope. Other methods in the class cannot access them.

8. What are the default values assigned to variables in Java?

Local variables do not receive default values and must be initialized before use, otherwise a compilation error occurs.

Instance variables receive default values when an object is created:

  • Reference types → null
  • Numeric types → 0
  • Boolean → false

9. What is data encapsulation?

Data encapsulation is an OOP concept that binds data and related methods into a single unit. It ensures modularity, improves maintainability, and protects data through controlled access, thereby supporting data hiding and security.

10. Explain the JIT compiler

JIT (Just-In-Time) compiler enhances runtime performance by compiling frequently used bytecode into native machine code.

How it works:

  1. Java source code is compiled into bytecode using javac.
  2. JVM loads .class files and initially interprets them.
  3. JIT identifies frequently executed methods and compiles them into optimized native code.
  4. JVM executes this optimized code directly, improving execution speed.

11. Difference between equals() method and == operator

The == operator compares memory references for objects and values for primitives.
The equals() method compares the actual content of objects, making it suitable for object value comparison in OOP.

12. How do you declare an infinite loop in Java?

An infinite loop runs continuously without a terminating condition.

Using for loop: for (;;) {
// logic
}

Using while loop: while (true) {
// logic
}

Using do-while loop: do {
// logic
} while (true);

13. Can static methods be overloaded?

Yes, static methods can be overloaded as long as the method signatures differ.

14. Why is the main method static in Java?

The main() method must be static because JVM calls it using the class name without creating an object. Since execution begins from main(), it must exist independently of object instantiation.

15. Can static methods be overridden?

No. Static methods are resolved at compile time, not runtime. Therefore, runtime polymorphism does not apply, and static methods cannot be overridden.

16. Difference between static methods, static variables, and static classes

  • Static methods and variables belong to the class, not to instances, and are loaded when the class is loaded.
  • They can be accessed directly using the class name, such as Math.max().
  • Static classes can only be inner classes and behave like other static members.

17. What is the main purpose of garbage collection?

Garbage collection automatically removes unused and unreachable objects from heap memory, improving memory utilization. However, it does not guarantee sufficient memory availability at all times.

18. What is a ClassLoader?

A ClassLoader is part of the JRE that loads required classes into the JVM during runtime.
For example, when using Scanner, the ClassLoader loads it into memory.

19. Which memory is cleaned during garbage collection: Stack or Heap?

Garbage collection operates on the Heap memory.

Conclusion

Java is a versatile and easy-to-learn high-level programming language that offers robust tools and industry-grade standards for application development. It was among the earliest languages to introduce strong multithreading capabilities, making it well-suited for handling concurrency-related challenges. With its clean syntax, rich built-in features, and dependable performance, Java continues to be a preferred choice across the software development community, contributing to its steadily growing adoption.

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