Java is a widely used programming language for building web, desktop, mobile, and enterprise applications. It is known for its simple syntax, portability, and powerful features that make development easier and more secure.
- Supports object-oriented programming concepts like classes, objects, inheritance, and polymorphism
- Platform independent because of JVM support
- Secure and robust with strong memory management
Features of Java
Java offers features like object-oriented programming, platform independence, security, robustness, multithreading, and high performance.
- Object-Oriented Programming (OOP) supports modular and reusable code using classes and objects.
- Platform Independence allows Java programs to run on any operating system with a JVM.
- Robust and Secure provides strong memory management, exception handling, and built-in security features.
- Multithreading and Concurrency enables multiple tasks to execute simultaneously for better performance.
- Rich API and Standard Libraries offer extensive built-in libraries for common programming tasks.
- Frameworks for Enterprise and Web Development support building enterprise applications, web applications, and REST APIs.
- Open-Source Libraries provide a large ecosystem of libraries to extend functionality.
- Maintainability and Scalability make Java applications easy to maintain, enhance, and scale as requirements grow.
Understanding Hello World Program
The first program that developers usually write while learning any programming language is the Hello World program. It helps verify that the Java Development Kit (JDK) is installed correctly and introduces the basic structure of a Java program.
Traditional Hello World Program
This is the standard approach used in Java and works in all Java versions.
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}
Output
Hello World!
Simplified Hello World Program (Java 24+)
Starting with Java 24, Java supports a simplified program entry point that removes much of the boilerplate code, making it easier for beginners to learn the language.
class Geeks{
void main() {
System.out.println("Hello, World!");
}
}
Output
Hello, World!
Note: This simplified syntax is intended primarily for learning and small programs. Most real-world Java applications continue to use the traditional public static void main(String[] args) method.
Structure of a Java Program
The structure of a Java program defines the standard format for writing Java applications and includes essential components required for program execution.
How to run the above code?
- Write code in a file like HelloWorld.java.
- Java Compiler "javac" compiles it into bytecode "HelloWorld.class".
- JVM (Java Virtual Machine) reads the .class file and interprets the bytecode.
- The JVM initially interprets bytecode and uses JIT (Just-In-Time) compilation to convert frequently executed code into native machine code for better performance.
Famous Applications Built Using Java
- Android Apps are widely developed using Java, especially older Android applications and many existing enterprise apps.
- Netflix uses Java for many of its backend services and content delivery systems.
- Amazon uses Java in various backend systems to support its large-scale e-commerce platform.
- LinkedIn relies on Java to handle high traffic and build scalable backend services.
- Minecraft (Java Edition) is one of the world's most popular games and is developed in Java.
- Spotify uses Java in parts of its server-side infrastructure and backend services.
- Uber uses Java for several backend services, including trip management and data processing.
- NASA WorldWind is an open-source virtual globe application developed using Java.
Uses of Java
- Mobile App Development is widely used for building Android applications using Android Studio.
- Web Development is used to create web applications and REST APIs with frameworks like Spring, Spring Boot, Struts, and Hibernate.
- Desktop GUI Applications are developed using libraries such as JavaFX and Swing.
- Enterprise Applications power banking systems, ERP software, and other large-scale business applications.
- Game Development is supported through frameworks and engines like LibGDX and jMonkeyEngine.
- Big Data Technologies use Java in platforms such as Hadoop and Apache Kafka for processing large datasets.
- Internet of Things (IoT) enables Java to run on embedded systems and smart devices.
- Cloud-Based Applications are built and deployed on platforms like AWS, Azure, and Google Cloud.
- Scientific Applications use Java to develop tools for processing and analyzing large volumes of scientific data..