Java Fundamentals - Programming

Primitives like int and double hold raw values directly and are fast and lightweight. Wrapper classes like Integer and Double are objects that box those values, enabling use in collections and providing helper methods. Java autoboxes between them, but wrappers can be null and carry object overhead, so primitives are preferred for plain calculations.

Java is a class-based object-oriented language, so all code, including the main method, lives inside a class. Even a simple program needs a class as its container. This design enforces structure and encapsulation. The main method with the signature public static void main is the entry point the JVM calls to start execution.

The Java Virtual Machine runs compiled Java bytecode. Your source compiles to platform-independent .class bytecode, and the JVM interprets and just-in-time compiles it to native instructions on whatever operating system it runs. This is what gives Java its write once, run anywhere portability, since the same bytecode runs on any machine with a JVM.

For objects, == compares references, checking whether two variables point to the same object in memory. The equals method compares values according to the class's definition. For example, two different String objects with the same characters are equal by equals but not by ==. Always use equals to compare object contents like strings.

Java fundamentals cover syntax, variables, data types, operators, and control flow, plus object-oriented concepts like classes, objects, inheritance, and interfaces. Core topics also include arrays, collections, exception handling, and the basics of the JVM. Mastering these gives you the foundation to read, write, and debug real Java applications confidently.

You can learn Java fundamentals free through the official Oracle tutorials, open documentation, and community exercises. Reputable Java books cover the language deeply with examples and exercises, which suits learners who prefer structured reading. Pair any resource with daily coding practice, since typing and debugging real programs cements the concepts faster than reading alone.

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