Interview Question Library

Java is an object-oriented, high-level language designed for 'Write Once, Run Anywhere' (WORA).

Java code is not compiled into .exe (Windows) or .app (Mac).

Java follows four pillars of OOP: Encapsulation (hiding internals), Abstraction (exposing only necessary features), Inheritance (reusing code), and Polymorphism (objects

Stack memory is used for thread execution and stores local variables and method call frames.

Java variables are categorized by scope: Local variables (within a method, stored on stack), Instance variables (within a class, stored on heap), and Static variables (sh

Encapsulation is the practice of keeping fields private and providing access through public methods (getters/setters).

JDK (Java Development Kit) is the full toolbox for developers: includes javac compiler, libraries, and JRE.

The JIT compiler is part of the JVM that speeds up execution by identifying 'hot spots' (code executed frequently) and compiling that bytecode into native machine code at

A constructor is a special block of code used to initialize a new object immediately after it is created.

Method Overloading is Compile-Time polymorphism: same method name, different parameters in the SAME class.

The 'static' keyword means that a member (variable/method) belongs to the CLASS itself rather than any specific instance.

These three are often confused: 'final' keyword makes a variable constant, a method un-overridable, or a class non-inheritable.