Data classes for value holders in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Kotlin data class?

A Kotlin data class is a special class designed to hold data. It automatically provides useful functions like <code>toString()</code>, <code>equals()</code>, <code>hashCode()</code>, and <code>copy()</code> without extra code.

beginner

How do you declare a data class in Kotlin?

Use the keyword <code>data</code> before the class name. For example: <br><code>data class User(val name: String, val age: Int)</code>

intermediate

What functions does Kotlin generate automatically for data classes?

Kotlin generates toString(), equals(), hashCode(), copy(), and componentN() functions for data classes.

beginner

Why use data classes instead of regular classes for value holders?

Data classes save time by automatically creating common functions. They make your code cleaner and easier to read when you just want to store data.

intermediate

Can a Kotlin data class have mutable properties?

Yes, properties in a data class can be mutable (<code>var</code>) or immutable (<code>val</code>). But immutable properties are preferred for value holders to keep data consistent.

Which keyword is used to declare a data class in Kotlin?

A val

B class

C object

D data

The data keyword before class declares a data class.

What function does Kotlin NOT automatically generate for data classes?

A equals()

B finalize()

C toString()

D copy()

Kotlin does not generate finalize() for data classes.

Which of these is a benefit of using data classes?

A Enforces immutability

B Faster runtime performance

C Automatic generation of common functions

D Allows multiple inheritance

Data classes automatically generate functions like toString() and copy().

Can a data class have mutable properties?

A Yes, using <code>var</code>

B No, only <code>val</code> is allowed

C Only if marked with <code>lateinit</code>

D Only inside companion objects

Data class properties can be mutable if declared with var.

What does the copy() function do in a data class?

A Creates a new instance with some properties changed

B Copies the class definition

C Copies the class to another file

D Copies the class to the clipboard

copy() creates a new object with optional property changes.

Explain what a Kotlin data class is and why it is useful for holding values.

Think about how data classes save you from writing repetitive code.

Describe the functions Kotlin automatically generates for data classes and their purpose.

These functions help with printing, comparing, copying, and destructuring.