What’s the difference between the Decorator, Proxy, and Adapter patterns in Java?

🚀 Java Interview Questions – Episode 5
💡 What’s the difference between the Decorator, Proxy, and Adapter patterns in Java?

These patterns may look similar in structure, but their intent and use cases are very different:

🎨 Decorator → Adds new behavior to an object dynamically without modifying its code.
Decorator is a structural pattern that allows adding new behaviors to objects dynamically by placing them inside special wrapper objects, called decorators.

🛡️ Proxy → Controls access to another object.
Used for lazy loading, security, or remote access.
Proxy is a structural design pattern that provides an object that acts as a substitute for a real service object used by a client. A proxy receives client requests, does some work (access control, caching, etc.) and then passes the request to a service object.

🔌 Adapter → Bridges two incompatible interfaces.
Makes mismatched APIs work together.
Adapter is a structural design pattern, which allows incompatible objects to collaborate.

🧠 Quick Summary:
Decorator = add functionality
Proxy = control access
Adapter = make incompatible things work together