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What is Java?

Reading Time: 5 Minutes
Difficulty: Beginner

Topic Summary​

Java is a high-level, object-oriented, platform-independent programming language used to build web applications, mobile apps, enterprise software, desktop applications, and backend systems.

Its biggest strength is "Write Once, Run Anywhere (WORA)", which means Java code can run on any device that has a Java Virtual Machine (JVM).

What You'll Learn​

  • What Java is
  • Why Java was created
  • Where Java is used
  • Why Java is still popular
  • Key features of Java

Prerequisites​

No prerequisites.

This is the first lesson of the Java Fundamentals module.

Introduction​

Imagine you write an application on your Windows laptop.

Normally, that application may not work on Linux or macOS without changes.

Java solved this problem by introducing the Java Virtual Machine (JVM), allowing the same compiled program to run on multiple operating systems.

This is why Java became one of the most trusted programming languages in the world.

Real-World Analogy​

Think of English.

People from different countries can communicate using English.

Similarly, Java communicates with different operating systems through the JVM.

Instead of creating different programs for Windows, Linux, and macOS, Java lets you write one program and run it on all supported platforms.

Where is Java Used?​

Java is widely used in:

  • Enterprise Applications
  • Banking Systems
  • E-Commerce Platforms
  • Android App Development
  • Web Applications
  • REST APIs
  • Cloud Applications
  • Big Data
  • Financial Software

Examples include many enterprise systems used by banks, insurance companies, governments, and large organizations.

⭐ Why is Java Popular?​

  • Platform Independent
  • Object-Oriented
  • Secure
  • Robust
  • High Performance
  • Huge Community
  • Rich API Library
  • Excellent Career Opportunities

First Java Program​

public class Main {

    public static void main(String[] args) {

        System.out.println("Hello Coding Life!");

    }

}

Output​

Hello Coding Life!

How Java Works (High Level)​

Java Source Code (.java)
          │
          ▼
      Java Compiler
        (javac)
          │
          ▼
   Bytecode (.class)
          │
          ▼
 Java Virtual Machine (JVM)
          │
          ▼
Operating System

Advantages​

  • Easy to Learn
  • Cross Platform
  • Secure
  • Object-Oriented
  • Strong Community Support
  • Large Job Market

Limitations​

  • Higher memory usage than some languages
  • Slower than C/C++ for low-level programming
  • Verbose syntax compared to newer languages

Best Practices​

  • Install the latest LTS version of Java.
  • Use meaningful variable names.
  • Follow Java naming conventions.
  • Learn OOP concepts early.

Common Misconceptions​

❌ Java and JavaScript are the same.

✅ They are completely different programming languages.

Interview Questions​

What is Java?​

Why is Java platform independent?​

What is WORA?​

What is JVM?​

What are the main features of Java?​

Quick Revision​

✔ Java is a programming language.

✔ Java is platform independent.

✔ Java uses JVM.

✔ Java follows Object-Oriented Programming.

✔ Java is widely used in enterprise applications.

  • History of Java
  • Features of Java
  • JDK vs JRE vs JVM

Next Lesson​

002 - History of Java