Java Platform Module System

🚀 Java Platform Module System (JPMS) – The Fun Version 🎭

Welcome to the exciting, slightly quirky world of JPMS (Java Platform Module System)! 🎩✨ Java 9 brought us something fancy called Project Jigsaw 🧩, and trust me, it’s a game-changer. If you’ve ever wrestled with dependencies and felt like you were coding inside a spaghetti bowl 🍝, then JPMS is here to save the day!

🧐 What the Heck is a Module Anyway?

Think of a module as a VIP club in your Java application. It has its own entrance (public APIs), its own secret rooms (private implementation), and it only lets in guests it trusts (explicit dependencies). In simple terms, modules are super-organized packages with extra rules.

🛡️ The Three Golden Rules of Modules

Strong Encapsulation 🔒 – Hide the messy details, so your module is like a magician’s trick – looks smooth on the outside, but nobody knows what’s happening underneath!
Stable Abstraction 🎭 – Offer clear and stable public APIs, so others can use your module without breaking things every time you tweak your code.
Explicit Dependencies 🧾 – Clearly declare what your module needs, avoiding those nasty surprise runtime errors that make you question your life choices.

🚨 The Java 8 Problem – A Messy Apartment 🏚️

Before Java 9, organizing your code was like living in an apartment with no walls – everything was just... there. Java used packages to group classes, and access modifiers (public, private, etc.) to control visibility. But dependency management? That was a total free-for-all. 😵‍💫

You imported whatever you needed. 🚚
You compiled your code. 📦
At runtime, everything could break because dependencies were unclear. 💥
Tools like Maven and Gradle became our band-aids. 🩹

🏆 JPMS to the Rescue

With Java 9, we get modules that actually know what they need. It’s like Marie Kondo came in and decluttered our dependencies. 🧹✨ Here’s how JPMS fixes our problems:

It modularizes the JDK itself – Meaning Java’s core is now a neat, structured set of modules instead of one giant blob.
It provides a module system for developers – So we can write clean, well-structured, and scalable applications.

🏗️ Java Base Module – The VIP of Java

Java 9 introduced a special java.base module – the mother of all modules. Every module automatically depends on it. No exceptions. It’s the Beyoncé of Java – you can’t ignore it. 🕶️

🧐 Modular vs. Non-Modular Code – Spot the Difference

A module is basically just a fancy jar file, with a module-info.class file in it.
To use a module, you put it in the modulepath instead of the classpath. (Yes, new terms to learn, yay! 🎉)
If you throw a modular jar into the classpath, Java ignores its module system and treats it like a normal jar. 🙄

🤓 How to Write Modular Code (Because You’re Fancy Now)

1️⃣ Create a Java Modular Project 🏗️

Start a new Java project. Give it a cool name. I chose JavaAppOne, but you can call it Codezilla if you want. 😎

2️⃣ Create Java Modules 📦

Let’s add two modules: helloworld and test.

Project Structure:

Java 9 Modules Project Structure
  ├── helloworld
  │   ├── module-info.java
  │   ├── com.howtodoinjava.demo.HelloWorldApp.java
  ├── test
  │   ├── module-info.java
  │   ├── com.test.TestApp.java

helloworld/module-info.java

module helloworld {
    exports com.howtodoinjava.demo;
}

HelloWorldApp.java

package com.howtodoinjava.demo;

public class HelloWorldApp {
    public static void sayHello() {
        System.out.println("Hello from HelloWorldApp");
    }
}

test/module-info.java

module test {
    requires helloworld;
}

TestApp.java

package com.test;

import com.howtodoinjava.demo.HelloWorldApp;

public class TestApp {
    public static void main(String[] args) {
        HelloWorldApp.sayHello();
    }
}

3️⃣ Finally, Run Your Modular Code 🏃

Output:

Hello from HelloWorldApp

BOOM. 💥 Modules are working! 🎉

🎯 The Final Word – Why Should You Care?

JPMS isn’t just another Java feature – it’s an architectural revolution. 🏛️ If you’ve ever heard horror stories about spaghetti architectures and messy monoliths, modularity is here to save the day. 🦸

But is JPMS perfect? Nope. 🤷 Some frameworks are still catching up, and it may take a while for full adoption. But Java has taken a big leap forward, and it’s worth getting ahead of the curve. 🚀