Careeroza

Real World Example

Delivery Tracking and Retries

Loops are everywhere in apps: a delivery tracker steps through stages, a network call is retried a few times before showing an error, and a list screen loads results page by page. Here is the logic behind a Swiggy-style tracker and a payment retry.

Example

Stages, retries with break, and pagination with ranges:

fun main() {
    val stages = listOf("Order placed", "Preparing", "Picked up", "Delivered")
    for ((i, stage) in stages.withIndex()) {
        val marker = if (i <= 2) "✔" else "○"   // current stage = 2
        println("$marker $stage")
    }

    val maxRetries = 3
    val serverRespondsOnAttempt = 2
    for (attempt in 1..maxRetries) {
        if (attempt == serverRespondsOnAttempt) {
            println("Attempt $attempt: payment confirmed")
            break
        }
        println("Attempt $attempt: timeout, retrying")
    }

    val totalItems = 23
    val pageSize = 10
    for (start in 0 until totalItems step pageSize) {
        val end = minOf(start + pageSize, totalItems)
        println("Loading restaurants ${start + 1}-$end")
    }
}

Output

✔ Order placed
✔ Preparing
✔ Picked up
○ Delivered
Attempt 1: timeout, retrying
Attempt 2: payment confirmed
Loading restaurants 1-10
Loading restaurants 11-20
Loading restaurants 21-23

Practice

Exercise: Print the 7 times table (7 x 1 = 7 ... 7 x 10 = 70) with a for loop, then print the even numbers from 20 down to 10 on one line using downTo and step.

Show answer
fun main() {
    for (i in 1..10) {
        println("7 x $i = ${7 * i}")
    }
    for (n in 20 downTo 10 step 2) print("$n ")
    println()
}