Java Introduction
Java Introduction
Java is one of the most popular and widely used programming languages in the world. It is used for developing desktop applications, web applications, mobile apps (Android), games, cloud systems, enterprise software, and more.
What is Java?
Java is:
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Object-Oriented
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Platform Independent
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High-Level
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Secure
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Robust and Reliable
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Distributed and Multithreaded
Java was created by James Gosling at Sun Microsystems in 1995 (now owned by Oracle).
Why is Java so Popular?
| Feature | Description |
|---|---|
| Write Once, Run Anywhere (WORA) | Java programs run on any system using JVM (Java Virtual Machine). |
| Object-Oriented | Uses concepts like classes, objects, inheritance, polymorphism, etc. |
| Secure | Provides strong memory management and built-in security features. |
| Rich API & Libraries | Comes with many built-in libraries for networking, GUI, data structures, etc. |
| Platform Independent | Java bytecode can run on Windows, Mac, Linux, or Android. |
| Huge Community & Support | Java is widely used in companies around the world. |
Java Architecture
Java follows this cycle:
Java Program Structure (Example)
Explanation:
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class Hello→ Defines a class named Hello. -
public static void main(String[] args)→ Starting point of the program. -
System.out.println()→ Prints text on the screen.
Java Applications
Java is used in:
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Android Apps
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Web Applications
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Enterprise Software (Banking, ERP)
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Cloud Computing
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Game Development
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IoT Devices
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Artificial Intelligence & Machine Learning (with Java libraries)
Java Editions
| Edition | Use Case |
|---|---|
| Java SE (Standard Edition) | Basic core Java for desktop and general apps. |
| Java EE (Enterprise Edition) | Used for large-scale distributed applications. |
| Java ME (Micro Edition) | Used in mobile and embedded systems. |
| JavaFX | Used for modern GUI-based desktop applications. |
Key Concepts in Java
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Variables and Data Types
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Operators
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Control Statements (
if,for,while) -
Methods and Functions
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OOP Concepts (Class, Object, Inheritance, Polymorphism, Encapsulation, Abstraction)
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Exception Handling
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Collections Framework
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Multithreading
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File Handling
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JDBC (Database Connectivity)
Advantages of Java
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Easy to learn
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Platform-Independent
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Community Support
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Secure and Stable
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Powerful for enterprise and web development
Disadvantages of Java
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Uses more memory compared to languages like C/C++
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Slightly slower because of JVM overhead
Who Uses Java? (Top Companies)
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Google
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Amazon
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Netflix
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LinkedIn
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Uber
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Instagram
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Spotify
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Oracle
