Why Generic class declaration in Kotlin? - Purpose & Use Cases

The Big Idea

What if you could write one class that magically fits any type you want?

The Scenario

Imagine you want to create a box that can hold any type of item--apples, books, or toys. Without generics, you'd have to make a new box class for each item type, like AppleBox, BookBox, ToyBox, and so on.

The Problem

This manual way is slow and boring. Every time you want a new box for a different item, you write almost the same code again. It's easy to make mistakes and hard to keep track of many similar classes.

The Solution

Generic class declaration lets you create one flexible box that works for any item type. You write the box code once, and it adapts to hold apples, books, or toys without extra work.

Before vs After

✗ Before

class AppleBox(val item: Apple)
class BookBox(val item: Book)

✓ After

class Box<T>(val item: T)

What It Enables

It makes your code reusable and clean, so you can handle many types easily with one smart class.

Real Life Example

Think of a shopping cart app where you want to store different products. Using a generic class, you can create one cart item class that works for clothes, electronics, or groceries without rewriting code.

Key Takeaways

Manual classes for each type cause repeated code and mistakes.

Generic classes let one class work with many types.

This saves time and keeps code simple and flexible.