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java

Curriculum Index

Current LevelInitiate
0/ 500 XP
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  • 1.1 The Anatomy of a Java Program
  • 1.2 JDK vs JRE vs JVM
Module 1: Hello Java & The JVM Engine•Lesson 2

1.2 JDK vs JRE vs JVM

### Understanding the Hierarchy

1. **JVM (Java Virtual Machine):** The abstract computing machine that executes bytecode instructions. It handles memory allocation, garbage collection, and hardware abstraction.
2. **JRE (Java Runtime Environment):** Contains the JVM plus the core Java Class Libraries (e.g., java.lang, java.util) necessary to run compiled applications.
3. **JDK (Java Development Kit):** The full developer bundle including JRE, compiler (javac), debugger (jdb), and packaging tools (jar).

**The WORA Principle (Write Once, Run Anywhere):**
Source Code (.java) $\xrightarrow{javac}$ Bytecode (.class) $\xrightarrow{JVM}$ Native Machine Code.

Conceptual Study Chapter

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