Which design patterns do you like the most and why do you use them?

I like the following design patterns and use them in Android development:

• MVVM (Model-View-ViewModel) — helps separate presentation logic from UI, making testing and maintenance easier. ViewModel manages data and state, while View is only responsible for display.

• Singleton — used to create a single instance of a class, for example, for a database manager or network client, to avoid unnecessary resources and ensure a unified state.

• Repository — abstracts data access, allowing the data source to be changed (local database, network) without altering the rest of the code.

• Observer (LiveData) — allows the UI to automatically respond to data changes, simplifying state synchronization and preventing memory leaks.

Using these patterns makes the code more modular, readable, and maintainable, which is especially important in large Android projects.