Tell about your experience using various design patterns in development practice.

In Android application development practice, I often use design patterns to improve the structure and maintainability of the code.

• MVVM (Model-View-ViewModel) — separates presentation logic and business logic, making testing and maintenance easier. ViewModel contains data and logic, View is responsible for display.

• Singleton — used to create a single instance, for example, for a database manager or network client.

• Observer — used in LiveData to update the UI when data changes.

• Factory — used to create objects with different configurations, such as different types of Views or fragments.

Example of using Singleton for a database manager:

object DatabaseManager {
    fun query(sql: String) { /* ... */ }
}

Using patterns helps make the code more modular, readable, and extensible.