Learning Java in 2025 is more exciting than ever. This guide covers everything — from writing your first
HelloWorld to deploying scalable microservices with Spring Boot and exploring Java's cutting-edge
features like virtual threads and native image compilation with GraalVM.
Bookmark this guide! Each section below will eventually link to a deep-dive blog post. For now, use this page as your complete overview and roadmap.
Java is a versatile, class-based, object-oriented language that has shaped enterprise computing since the mid-90s. Its philosophy? "Write Once, Run Anywhere." Java applications can run on any system with a JVM.
JAVA_HOME and verify with java -version.public class Hello {
public static void main(String[] args) {
System.out.println("Hello, Java!");
}
}var (since Java 10) for type inferenceJava is built on the pillars of OOP: Abstraction, Encapsulation, Inheritance, Polymorphism.
class Car {
String model;
Car(String model) {
this.model = model;
}
}Java allows code reuse through extends and overrides behavior using @Override.
Use private fields with public getters/setters. Abstract classes hide complexity.
Java 8+ interfaces can have default methods. Abstract classes can't be instantiated.
Use Thread, Runnable, ExecutorService for concurrency.
Use File, BufferedReader, FileWriter. Java NIO offers better performance.
Use try-catch-finally, create custom exceptions.
Use Socket, ServerSocket, HttpClient.
List<String> names = List.of("A", "B", "C");
names.stream().filter(n -> n.startsWith("A")).forEach(System.out::println);Use @Test, assertEquals in JUnit 5.
@RestController
public class ApiController {
@GetMapping("/hello")
public String hello() {
return "Hello from API!";
}
}Break monoliths with Spring Cloud, Eureka, Zuul, and Docker/Kubernetes integration.
Understand bytecode, memory model, garbage collection strategies (G1, ZGC).
psvm, sout shortcuts— Blog by Aelify (ML2AI.com)
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