What is Java used for?

Java is widely used for web applications, Android apps, enterprise systems, financial applications, automation tools, and backend services.

Is Java good for beginners?

Yes. Java has clear syntax, strong community support, and a stable learning curve, making it an excellent first programming language.

Is JVM the same as JDK?

No. JDK is used to develop Java programs. JRE is used to run them. JVM is the engine that executes bytecode.

Introduction to Java - Features, JVM, JDK, JRE

What is Java?

Java is a high-level, object-oriented, and platform-independent programming language. It is widely used for building web applications, Android apps, enterprise systems, automation tools, cloud applications, and more.

Java follows the principle of WORA (Write Once, Run Anywhere). This means once your program is compiled into bytecode, it can run on any device that has a Java Virtual Machine (JVM), regardless of operating system or hardware.

Features of Java

Simple: Designed to be easy for beginners. Java removes complex concepts like pointers and manual memory management.
Object-Oriented: Java is built around classes and objects, making it easy to model real-world problems.
Platform Independent: Java code is compiled into bytecode that can run on any platform with a JVM.
Secure: Java applications run inside a virtual machine with restricted access, reducing security risks.
Robust: Java has strong memory management, automatic garbage collection, and powerful exception handling.
Multithreaded: Java can perform multiple tasks simultaneously, which is useful for games, animations, or background tasks.

JVM, JRE, and JDK – Differences Explained

The three core components of Java are:

Acronym	Full Form	Role
JDK	Java Development Kit	Includes development tools like compiler (`javac`), debugger, and also contains JRE.
JRE	Java Runtime Environment	Allows you to run Java applications; contains JVM + core libraries.
JVM	Java Virtual Machine	Executes Java bytecode and converts it into machine code understood by your OS.

                 ┌──────────────┐
                 │     JDK      │  ← Development Tools + JRE
                 └──────┬───────┘
                        │
                 ┌──────┴───────┐
                 │     JRE      │  ← JVM + Libraries
                 └──────┬───────┘
                        │
                 ┌──────┴───────┐
                 │     JVM      │  ← Executes Java Bytecode
                 └──────────────┘

How Java Code Runs (Execution Flow)

Every Java program goes through these steps:

Writing the Program: You create a source code file ending with .java.
Compilation: The Java compiler (javac) converts your source code into bytecode stored in a .class file.
Execution: The JVM loads the bytecode, verifies it for safety, translates it into machine code, and executes it.

Source Code (.java) 
       ↓ compilation
Bytecode (.class)
       ↓ executed by
Java Virtual Machine (JVM)

Setting Up Your Java Development Environment

Download and install the latest JDK (Oracle JDK or OpenJDK).
Set the JAVA_HOME environment variable.
Install an IDE such as:
- IntelliJ IDEA (recommended)
- Eclipse
- VS Code with Java Extensions
Verify installation using:
```
java -version
javac -version
        
```

Introduction to Java