What are the main features of Java?

Java's main features include platform independence through bytecode, object-oriented programming, robustness, security, multithreading, and automatic memory management through garbage collection.

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

JVM (Java Virtual Machine) executes Java bytecode. JRE (Java Runtime Environment) contains JVM plus libraries needed to run Java applications. JDK (Java Development Kit) includes JRE plus development tools like compilers and debuggers needed to create Java programs.

What is object-oriented programming in Java?

Object-oriented programming in Java is a paradigm that uses objects containing data (attributes) and methods (functions) to design applications. Key OOP concepts in Java include encapsulation, inheritance, polymorphism, and abstraction.

What are Java access modifiers?

Java has four access modifiers: public (accessible from anywhere), protected (accessible within package and subclasses), default (accessible within package only), and private (accessible within class only).

What is the difference between ArrayList and LinkedList?

ArrayList uses a dynamic array that provides fast random access but slower insertions/deletions. LinkedList uses a doubly-linked list that provides faster insertions/deletions but slower random access.

Java Interview Questions - JavaTechOnline

Last Updated on February 24th, 2026

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