When as expression returning value in Kotlin - Mini Project: Build & Apply

Using When as an Expression Returning a Value in Kotlin

📖 Scenario: You are creating a simple program that assigns a message based on a day number. This is like checking the day of the week and giving a friendly note.

🎯 Goal: Build a Kotlin program that uses when as an expression to return a message string based on a day number.

📋 What You'll Learn

Create an integer variable day with the value 3

Create a variable message that uses when as an expression to assign a string based on day

Use when with cases for days 1 to 7, returning the correct day name

Print the message variable

💡 Why This Matters

🌍 Real World

Using <code>when</code> expressions helps in apps to decide actions based on user input or data values, like showing messages or choosing options.

💼 Career

Understanding <code>when</code> expressions is important for Kotlin developers to write clean and readable decision-making code.

1

Create the day variable

Create an integer variable called day and set it to 3.

Kotlin

# Create an integer variable called day and set it to 3
# Your code here

Need a hint?

Use val day = 3 to create the variable.

2

Set up the when expression

Create a variable called message that uses when as an expression on day. Start the when expression with cases for 1 and 2 returning "Monday" and "Tuesday" respectively.

Kotlin

val day = 3
# Create a variable message using when expression on day with cases 1 and 2
# Your code here

Need a hint?

Use val message = when(day) { 1 -> "Monday"; 2 -> "Tuesday"; else -> "Unknown" }.

3

Add all days to the when expression

Extend the when expression for message to include all days from 1 to 7 returning "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", and "Sunday" respectively.

Kotlin

val day = 3
val message = when(day) {
    1 -> "Monday"
    2 -> "Tuesday"
    # Add cases for 3 to 7 here
    else -> "Unknown"
}

Need a hint?

Add all days as cases in the when expression.

4

Print the message

Write a println statement to print the message variable.

Kotlin

val day = 3
val message = when(day) {
    1 -> "Monday"
    2 -> "Tuesday"
    3 -> "Wednesday"
    4 -> "Thursday"
    5 -> "Friday"
    6 -> "Saturday"
    7 -> "Sunday"
    else -> "Unknown"
}
# Print the message variable
# Your code here

Need a hint?

Use println(message) to show the result.