RunBlocking for bridging in Kotlin - Mini Project: Build & Apply

Using runBlocking to Bridge Coroutines and Regular Code

📖 Scenario: Imagine you have a simple Kotlin program where you want to run a coroutine to fetch a message but your main function is not a coroutine. You need a way to wait for the coroutine to finish and get the result before continuing.

🎯 Goal: You will create a coroutine using runBlocking to bridge between regular code and coroutine code, then print the fetched message.

📋 What You'll Learn

Create a suspend function called fetchMessage that returns a String

Use runBlocking in the main function to call fetchMessage

Store the result of fetchMessage in a variable called message

Print the message variable

💡 Why This Matters

🌍 Real World

In real apps, you often need to call suspend functions from regular code, like in main functions or tests. <code>runBlocking</code> helps you wait for coroutine results safely.

💼 Career

Understanding how to bridge coroutines with regular code is important for Kotlin developers working on backend, Android, or desktop applications where asynchronous tasks are common.

1

Create the suspend function fetchMessage

Write a suspend function called fetchMessage that returns the string "Hello from coroutine!".

Kotlin

# Your code here

Need a hint?

A suspend function is declared with the suspend keyword before fun.

2

Use runBlocking in main to call fetchMessage

Write a main function that uses runBlocking to call fetchMessage and store the result in a variable called message.

Kotlin

suspend fun fetchMessage(): String {
    return "Hello from coroutine!"
}

// Your code here

Need a hint?

Use val message = runBlocking { fetchMessage() } inside main.

3

Print the message variable

Add a line inside the main function to print the message variable.

Kotlin

import kotlinx.coroutines.runBlocking

suspend fun fetchMessage(): String {
    return "Hello from coroutine!"
}

fun main() {
    val message = runBlocking {
        fetchMessage()
    }
    // Your code here
}

Need a hint?

Use println(message) to show the message on the screen.

4

Run the program and see the output

Run the program and observe the output. It should print Hello from coroutine!.

Kotlin

import kotlinx.coroutines.runBlocking

suspend fun fetchMessage(): String {
    return "Hello from coroutine!"
}

fun main() {
    val message = runBlocking {
        fetchMessage()
    }
    println(message)
}

// Run the program to see the output

Need a hint?

Run the program and check the console output.