Dezign Patterns

Encapsulation

📦 Definition: Wrapping data (variables) and code (methods) into a single unit (class).
🎯 Intent : Protect the object's state from direct access.

• Before OOPS, most of the code was procedural — meaning functions and data were separate. This made codebases messy.
• Any function could change any data at any time.
• No control over how values were set or used - No consistency or safety

In java, we make fields private and accessing/modifying fields using public getters/setters

private int age;    // private = encapsulated

public void setAge(int age) {
    if (age > 0) {      // Public setter for age (with validation)
      this.age = age;
    }
}
public double getSalary() {
    
    return Math.round(salary * 100.0) / 100.0;  // Return formatted or adjusted value
}