Fetch data without freezing the app.

Network data is unreliable by default. A junior Android app must handle loading, success, empty, and error states explicitly.

Network states

DTO and mapper

data class BusinessDto(
    val id: Int,
    val name: String,
    val category: String,
    val city: String,
    val phone: String?
)

data class Business(
    val id: Int,
    val name: String,
    val category: String,
    val city: String,
    val phone: String
)

fun BusinessDto.toBusiness(): Business {
    return Business(
        id = id,
        name = name.trim(),
        category = category,
        city = city,
        phone = phone ?: "Not available"
    )
}

Keep DTOs separate from UI models. Network payloads often contain nulls, naming mismatches, or fields your UI should not trust directly.

Practice task

• Create DTO and UI model classes.
• Map nullable API fields into safe UI values.
• Show loading, success, empty, and error screens.
• Add a Retry button that repeats the request.