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Listing the cart

Write the function that prints the cart formatted.

Listing the cart

To print the items in the cart, use a for loop. Each item is a Product; its fields are accessed with item.name and item.price.

for (item in cart) {
    println("${item.name}: ${item.price}")
}
// Apple: 5.0
// Bread: 3.0

Each loop step, item represents one product. The template ${item.name} embeds the name, ${item.price} the price.

This format is handy for showing the cart to the user.

Practice List the items

Add a for (item in cart) { println("${item.name}: ${item.price}") } loop to the previous cart (two items + total). Each item should be on its own line: "Apple: 5.0" and "Bread: 3.0".

Starter code

Main.kt
data class Product(val name: String, val price: Double)

fun main() {
    val cart = mutableListOf<Product>()
    cart.add(Product("Apple", 5.0))
    cart.add(Product("Bread", 3.0))
    val total = cart.sumOf { it.price }
    // List the items
}

Sample solution

Main.kt
data class Product(val name: String, val price: Double)

fun main() {
    val cart = mutableListOf<Product>()
    cart.add(Product("Apple", 5.0))
    cart.add(Product("Bread", 3.0))
    val total = cart.sumOf { it.price }
    for (item in cart) {
        println("${item.name}: ${item.price}")
    }
}

Expected output

Apple: 5.0
Bread: 3.0

Formatted output

To make the output more readable, templates and formatting are used. ${item.name}: ${item.price} shows each item on one line.

// Output:
// Apple: 5.0
// Bread: 3.0

A colon and space separate the name and price. Without templates you'd write item.name + ": " + item.price; templates are shorter.

Each item is on its own line; println adds the line break automatically.

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What is used to print every item in the cart?

  • if statement
  • for loop Correct answer
  • when statement
  • println alone

Explanation: A for loop visits each item in the list in turn.

2 Complete the for loop

Question 
for (____ in cart) { println("${item.name}: ${item.price}") }
Answer 
for (item in cart) { println("${item.name}: ${item.price}") }

Explanation: for (item in cart) takes each product in turn.

3 Match the listing concepts

Term Meaning
for (item in cart) List loop
item.name Item name
item.price Item price
${item.name} Template

All lessons in Beginner

1 Kotlin basics

  1. What is Kotlin?
  2. Your first program
  3. The main function
  4. Comments
  5. String templates
  6. Summary - Kotlin basics

2 Variables

  1. val and var
  2. Type inference
  3. const
  4. lateinit
  5. by lazy
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. Boolean and Char
  4. String
  5. Any and Unit
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Error handling
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Elvis operator
  6. Summary - Operators

6 Strings

  1. Creating strings
  2. String templates
  3. String methods
  4. substring
  5. split and replace
  6. Summary - Strings

7 Conditionals

  1. The if statement
  2. else and else if
  3. if expression
  4. when
  5. when expression
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. Range
  5. break and continue
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding items
  3. Calculating totals
  4. Listing the cart
  5. Putting it together

10 Arrays

  1. Creating arrays
  2. Array access
  3. Array size
  4. Array loop
  5. Array methods
  6. Summary - Arrays

11 Lists

  1. Creating lists
  2. List operations
  3. List access
  4. List iteration
  5. List methods
  6. Summary - Lists

12 Maps and Sets

  1. Creating sets
  2. Set operations
  3. Creating maps
  4. Map operations
  5. Map iteration
  6. Summary - Maps and Sets

13 Functions

  1. Defining functions
  2. Return values
  3. Expression body
  4. Default parameters
  5. Named arguments
  6. Summary - Functions

14 Null safety

  1. Nullable types
  2. ?, !! and ?:
  3. let
  4. Null check
  5. lateinit
  6. Summary - Null safety

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 Advanced string operations

  1. Regex
  2. matches and find
  3. replace
  4. StringBuilder
  5. trim and pad
  6. Summary - Advanced strings

17 Enums

  1. enum class
  2. Enum values
  3. Enum properties
  4. when with enum
  5. Enum and range
  6. Summary - Enums

18 Exceptions

  1. try/catch
  2. throw
  3. finally
  4. try expression
  5. Custom exceptions
  6. Summary - Exceptions

19 Class basics

  1. class
  2. Constructor
  3. Properties
  4. Methods
  5. this
  6. Summary - Class basics

20 Beginner final

  1. Project design
  2. Classes
  3. Collections
  4. Error handling
  5. Putting it together