Let function behavior and use cases in Kotlin - Mini Project: Build & Apply

Let function behavior and use cases

📖 Scenario: Imagine you have a list of names and you want to print a greeting only for the names that are not null. Using Kotlin's let function helps you do this safely and cleanly.

🎯 Goal: You will create a list with some nullable names, then use the let function to print greetings only for the non-null names.

📋 What You'll Learn

Create a list called names with nullable String values including null

Create a variable called greetingPrefix with the value "Hello"

Use a for loop to iterate over names and apply the let function to print greetings only for non-null names

Print the greeting in the format: Hello, [name]!

💡 Why This Matters

🌍 Real World

Handling nullable data safely is common in apps that get input from users or external sources. Using let helps avoid crashes and keeps code clean.

💼 Career

Understanding Kotlin's let function is important for Android developers and anyone working with Kotlin to write safe and readable code.

1

Create a list with nullable names

Create a list called names with these exact values: "Alice", null, "Bob", null, "Charlie"

Kotlin

# Create a list called names with nullable String values
# Your code here

Need a hint?

Use listOf to create the list and include null values where specified.

2

Create a greeting prefix variable

Create a variable called greetingPrefix and set it to the string "Hello"

Kotlin

val names: List = listOf("Alice", null, "Bob", null, "Charlie")
# Create a variable greetingPrefix with value "Hello"
# Your code here

Need a hint?

Use val greetingPrefix = "Hello" to create the variable.

3

Use let function to greet non-null names

Use a for loop with variable name to iterate over names. Inside the loop, use the let function on name to print the greeting in the format Hello, [name]!

Kotlin

val names: List = listOf("Alice", null, "Bob", null, "Charlie")
val greetingPrefix = "Hello"

# Use a for loop and let function to print greetings for non-null names
# Your code here

Need a hint?

Use name?.let { ... } to run code only when name is not null.

4

Print the greetings

Run the program to print greetings for all non-null names in the list. The output should be exactly:
Hello, Alice!
Hello, Bob!
Hello, Charlie!

Kotlin

val names: List = listOf("Alice", null, "Bob", null, "Charlie")
val greetingPrefix = "Hello"

for (name in names) {
    name?.let {
        println("$greetingPrefix, $it!")
    }
}

# Run the program to see the output

Need a hint?

Make sure your program prints exactly the greetings for non-null names, each on its own line.