Java Core Training | Samyak Computer Classes Career Program
Java Core" is a broad territory, but it generally refers to the fundamental libraries and concepts required to build any Java application—without getting into enterprise frameworks like Spring or Jakarta EE.
Think of it as the DNA of the language. Here is a breakdown of the essential pillars that make Java what it is:
1. The Execution Model (JVM, JRE, JDK)
Java’s "Write Once, Run Anywhere" (WORA) philosophy relies on its runtime environment.
JVM (Java Virtual Machine): The engine that executes the bytecode. It handles memory management and provides a platform-independent environment.
JRE (Java Runtime Environment): Includes the JVM plus the standard libraries needed to run Java programs.
JDK (Java Development Kit): The full toolbox. It includes the JRE plus development tools like the compiler (javac) and debugger.
2. Object-Oriented Programming (OOP)
Java is strictly object-oriented. Everything (mostly) revolves around four core principles:
Encapsulation: Hiding internal data via private fields and providing access through getters/setters.
Inheritance: Allowing a class (subclass) to acquire properties of another (superclass).
Polymorphism: The ability of an object to take many forms (Method Overloading and Overriding).
Abstraction: Using abstract classes and interfaces to hide complexity and show only essential features.
3. Core Syntax & Data Types
Primitives: Simple types like int, double, boolean, and char.
Reference Types: Objects, Strings, and Arrays.
Control Flow: The standard if-else, switch (including modern switch expressions), and loops (for, while, do-while).
4. The Collections Framework
Since you can't just use arrays for everything, Java provides a sophisticated set of data structures:
Interface Key Implementation Characteristics
List ArrayList, LinkedList Ordered, allows duplicates.
Set HashSet, TreeSet Unordered, no duplicates.
Map HashMap, TreeMap Key-Value pairs.
Queue PriorityQueue First-in, first-out (usually).
5. Exception Handling