Top 25 Java Interview Questions

Java remains one of the most widely used programming languages in the software industry. Many companies test Java fundamentals during technical interviews.

1. What is Java?

Java is an object-oriented programming language developed by Sun Microsystems. It is platform-independent and follows the principle of “Write Once, Run Anywhere”.

2. What are the main features of Java?

• Object-Oriented
• Platform Independent
• Secure
• Robust
• Multithreaded

3. What is JVM?

JVM (Java Virtual Machine) executes Java bytecode and allows Java programs to run on any operating system.

4. What is the difference between JDK, JRE, and JVM?

• JDK – Java Development Kit
• JRE – Java Runtime Environment
• JVM – Executes Java bytecode

5. What is OOP?

Object-Oriented Programming focuses on objects and classes. Key concepts include encapsulation, inheritance, polymorphism, and abstraction.

Interview Preparation Tip

Practice coding problems regularly and revise core Java concepts like collections, multithreading, and exception handling before attending interviews.