Java Programming Basics Review

Java Programming Basics

• Java is a high-level, class-based, object-oriented programming language, designed for platform independence.
• Originally developed by Sun Microsystems and released in 1995; now owned by Oracle with over three billion devices running Java.
• Key features include platform independence, automatic memory management, multithreading, rich standard library, and built-in security.

Core Features

• Platform Independence: Java compiles code into bytecode, enables execution on any platform with a compatible Java Virtual Machine (JVM); adheres to the principle of “write once, run everywhere.”
• Object-Oriented: Utilizes objects and classes to structure code, promoting reusability and organization.
• Syntax: Similar to C++, making it accessible for developers and enhancing learning through simplified structures.
• Automatic Memory Management: Incorporates a garbage collector to manage memory allocation and deallocation, preventing memory leaks.
• Multithreading: Allows concurrent execution of multiple tasks, improving application performance and responsiveness.
• Rich Standard Library: Offers extensive libraries for data structures, networking, file handling, etc.
• Security: Features such as Java sandbox and bytecode verification safeguard against malicious code.

Data Types

• Definition: Classifications that determine variable value types, available operations, memory allocation, and data representation.
• Primitive Data Types: Basic types with fixed size, including boolean, character, byte, short, int, long, float, and double.
• Non-Primitive Data Types: Reference types representing collections or structures, encompassing arrays, strings, classes, objects, lists, queues, stacks, graphs, and trees.

Objects and Classes

• Class: A blueprint for creating objects, encapsulating common characteristics and behaviors.
• Object: An instance of a class that defines data storage and methods for data manipulation.
• Instance Variables: Also referred to as fields, representing data related to a class object; can be base types or reference types.
• Methods: Code blocks callable to execute actions, capable of accepting parameters, with behaviors tied to invoking objects and passed parameters.

Modifiers

• Access Modifiers: Control visibility of class components:
  • Public: Accessible from any other class.
  • Protected: Accessible within the same package and by subclasses.
  • Default: Accessible only within the same package (no modifier).
• Static Modifier: Indicates class membership over instance membership for variables or methods.
• Abstract Modifier: Allows declaration of abstract classes and methods, facilitating advanced OOP features combined with inheritance.
• Final Modifier: Defines constants, disallows method overriding, and prevents class inheritance; values assigned at declaration cannot change.

Java Operators

• Arithmetic Operators: Perform basic mathematical operations such as addition (+), subtraction (-), multiplication (*), division, etc.