🟢 Spring Core in Simple Words – My Beginner Notes

👋 Introduction

I’ve recently started my tech journey as a backend Java developer. While learning the Spring Framework, I decided to write beginner-friendly blogs to help others like me and revise what I learn along the way.
This blog is focused on understanding Spring Core — the heart of the Spring Framework.

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🌱 What is Spring Core?

Spring Core is the fundamental part of the Spring Framework.
It provides the base features like:

• Dependency Injection (DI)

• Inversion of Control (IoC)

• Managing application objects (called Beans)

In simple words: Spring Core helps you connect different parts of your code without hardcoding their connections.

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🔄 What is Dependency Injection?

Let’s understand DI with a small example.

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🧩 Without Dependency Injection:

public class Car {
    Engine engine = new Engine(); // Car creates the Engine itself

    public void drive() {
        engine.start();
    }
}

Here, the Car class is tightly connected with the Engine. It creates the engine — so it can’t be reused easily or tested independently.

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✅ With Dependency Injection:

public class Car {
    private Engine engine;

    public Car(Engine engine) { // Engine is given from outside
        this.engine = engine;
    }

    public void drive() {
        engine.start();
    }
}

Now, Car doesn't create the engine. It receives it from outside. That’s Dependency Injection.

Spring uses DI to connect objects and manage them for you behind the scenes.

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🧠 Why is Spring Core Useful?

• Helps in writing clean, testable, and reusable code

• You don’t have to manually create and connect objects

• Makes large applications easier to manage

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🛠️ My Understanding So Far

As a beginner, I feel Spring Core makes coding easier once you understand the basics. The concept of DI was new to me at first, but now it feels logical — especially for large-scale apps where objects are everywhere.

This blog is just the start. I’ll keep sharing my weekly learning here.

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🔗 Connect With Me

• 🔹 LinkedIn – Varshitha

• 🔹 GitHub – Varshithays

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🔜 Coming Next Week:

🔹 What is a Spring Bean?
🔹 How to create and manage Beans in Spring Core?

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Thanks for reading! 🚀