This document discusses using generics in Kotlin to create reusable classes. It provides examples of different types of quiz questions that could each be represented by their own class, but outlines how a generic class can be used instead with a placeholder data type for the answer. The document then demonstrates refactoring the code to use a generic Question class that can store an answer of any data type specified when instantiating the class.

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Compose Camp
Session 3
Google Developer Student Clubs
M.S.Bidve Engineering College Latur

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Unit 3:
DISPLAY LISTS AND
USE USE MATERIAL
DESIGN

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Contents
-Kotlin fundamentals
-Build a scrollable list
-Display list
-Material design

4. This work is licensed under the Apache 2.0 License
Generics, Objects and Extensions
Make a reusable class with generics
Let’s say you’re writing an app for an online quiz , similar to the
quizzes you’ve seen in this course. There are often multiple types
of quiz questions, such as fill in the blank, or true or false. An
individual quiz question can be represented by a class, with
several properties
1. Fill in the blank question: The answer is a word represented
by a string.
2. True or false question: The answer is represented by a
boolean.
3. Math problems: The answer is numeric value. The answer for
a simple arithmetic problem is represented by an int.

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What is Generic Data Type?
Generic types, or generics for short, allow a data type, such as class, to specify an unknown
place holder data type that can be used with its properties and methods. What exactly does
this mean?
In the above example, instead of defining an answer properly for each possible data type,
you can create a single class to represent any question, and use a placeholder name for the
data type of the answer properly. The actual data type string, int, boolean, etc. is specified
when that class is instantiated. Wherever the placeholder name is used, the data type
passed into the class is used instead.

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Refactor Your Code to Use Generics
A generic data type is provided when instantiating a class, so it
needs to be defined as part of the class signatures. After the
class name comes a left facing (<), followed by a placeholder
name for the data type, followed by right facing angle bracket
(>).
The placeholder name can then be used wherever you use a real
data type within the class such as for a property.
Refactor
Refactor your code to use a single class name question with a
generic answer property
class Questions<T>(
val questionText:
String,
val answer : T,
val difficulty: String
)
class Class name < generic data type
properties
>(
)

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https://developer.android.com/courses/and
roid-basics-compose/unit-3