Let function with safe calls in Kotlin - Mini Project: Build & Apply

Using the Let Function with Safe Calls in Kotlin

📖 Scenario: Imagine you have a list of names that might contain some null values. You want to greet each person only if their name is not null. Using Kotlin's let function with safe calls helps you do this safely and cleanly.

🎯 Goal: Build a Kotlin program that uses the let function with safe calls to print greetings only for non-null names.

📋 What You'll Learn

Create a list called names with some String? values including null

Create a variable called greetingPrefix with the value "Hello"

Use a for loop to go through each name in names

Inside the loop, use a safe call with let to print a greeting only if the name is not null

💡 Why This Matters

🌍 Real World

Handling data that might be missing or null is common in apps. Using safe calls with let helps avoid errors and keeps code clean.

💼 Career

Many Kotlin jobs require safe handling of nullable data to prevent crashes and bugs, especially in Android development.

1

Create the list of names

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

Kotlin

# Create the list called names with the given values
# Your code here

Need a hint?

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

2

Add a greeting prefix

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

Kotlin

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

Need a hint?

Use val to create an immutable variable for the greeting prefix.

3

Use let with safe calls to greet non-null names

Write a for loop using name to iterate over names. Inside the loop, use a safe call with name?.let to print "$greetingPrefix, $it!" only if name is not null

Kotlin

val names: List = listOf("Alice", null, "Bob", null, "Charlie")
val greetingPrefix = "Hello"
# Add a for loop to iterate over names
# Inside the loop, use safe call with let to print greeting
# 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 using the println statement inside the let block

Kotlin

val names: List = listOf("Alice", null, "Bob", null, "Charlie")
val greetingPrefix = "Hello"
for (name in names) {
    name?.let {
        // Print greeting here
    }
}

Need a hint?

Make sure the println is inside the let block to print only for non-null names.