Java Interface Explained with Real Examples – Complete Java Tutorial

By Bhau Automation • Java Basics, Interface Examples, Real Use Cases

🎯 What You Will Learn

What is an Interface in Java?
Why interfaces are important
Rules of Java interfaces
Difference between Class, Abstract Class, and Interface
Real-time examples of interfaces
Java interface interview questions

📌 What is a Java Interface?

A Java Interface is a blueprint of a class. It contains abstract methods (method without body) that are implemented by classes.

💡 Interfaces tell WHAT to do, classes tell HOW to do it.

💡 Features of Java Interface

Interfaces support multiple inheritance
All methods are abstract by default
Variables inside interface are public static final
Helps achieve loose coupling
Improves code structure & maintenance

📘 Java Interface Syntax

interface Animal {
    void sound(); // abstract method
}

🐶 Example: Interface Implementation

interface Animal {
    void sound();
}

class Dog implements Animal {
    public void sound() {
        System.out.println("Dog Barks");
    }
}

class TestInterface {
    public static void main(String[] args) {
        Animal a = new Dog();
        a.sound();
    }
}

🧠 Output

Dog Barks

🔍 Why Use Interfaces?

To achieve abstraction
To achieve multiple inheritance
To support API integrations
To implement loose coupling in Java applications
To follow coding best practices used by professional Java developers

📌 Real-Time Use Case Example

Every automation framework (Selenium, API Testing) uses interfaces for WebDriver, List, Set, Map etc.

WebDriver driver = new ChromeDriver();

Here, WebDriver is an interface, and ChromeDriver is the implementation.

🆚 Difference: Class vs Abstract Class vs Interface

Feature	Class	Abstract Class	Interface
Methods	Concrete	Both	Abstract only
Variables	Normal	Normal	public static final
Multiple Inheritance	❌	❌	✔️

❓ Java Interface Interview Questions

Q1: Can we create an object of an interface?

A: No, but we can create object of implementing class.

Q2: Can interface contain constructors?

A: No, because interface cannot create objects.

Q3: Why interface variables are final?

A: Because interfaces define constants, not state.

🎥 Watch the Complete Java Interface Tutorial

👉 Watch on YouTube: Java Interfaces Explained

🚀 Key Takeaways

Interfaces are blueprints of classes
Used in real-time Java development
Supports multiple inheritance
Essential for Java beginners & professionals
Highly asked in Java interviews

⚡ Mastering interfaces will make you a confident Java developer!

🚀 Created with ❤️ by Bhau Automation

Java Interface Explained with Examples – Complete Java Tutorial for Beginners