Could you give an example of principle D from SOLID principles demonstrating its practical application?

The Dependency Inversion Principle (D) of SOLID states that:

• High-level modules should not depend on low-level modules. Both should depend on abstractions.
• Abstractions should not depend on details. Details should depend on abstractions.

Example in Android:

Suppose you have a class that retrieves data from the network (lower level) and a class that displays this data (upper level). Instead of the display class depending directly on a specific network implementation, you create an interface (abstraction) that describes data retrieval.

interface DataSource {
    fun getData(): String
}

class NetworkDataSource : DataSource {
    override fun getData() = "Data from network"
}

class DataPresenter(private val dataSource: DataSource) {
    fun present() {
        println(dataSource.getData())
    }
}

fun main() {
    val networkDataSource = NetworkDataSource()
    val presenter = DataPresenter(networkDataSource)
    presenter.present()
}

This approach allows easy swapping of data sources (e.g., to a local database or a mock for tests) without changing the display logic, which aligns with the dependency inversion principle.