1. How can you keep data persist when an Android app stops unexpectedly? What are the methods exist for data preservation in Android and which one is the most suitable for dealing with various configurations and lifecycles?

To keep your app's data safe even if it closes unexpectedly or the device restarts or process death, Android offers several ways to save your data:

1. SharedPreferences: Perfect for saving small pieces of information like settings or user preferences in key-value pairs.

2. Internal Storage: Good for storing private data that other apps shouldn't access, like user files within your app's own space.

3. External Storage: Use this for large files that you might want to share with other apps or the user, like photos or videos.

4. SQLite Database: When you have structured data (like a list of contacts or game scores), this is a great way to organize and query your data with SQL.

5. Room Persistence Library: This is a modern layer on top of SQLite that makes it easier to work with databases. It handles a lot of the heavy lifting for you.

6. Content Providers: If your app needs to share data with other apps, content providers create a standardized interface for doing so.

7. DataStore: A newer and more flexible solution than SharedPreferences for storing key-value pairs or typed objects. It uses Kotlin coroutines and Flow to store data asynchronously, safely, and with less boilerplate code.

Choosing the best method depends on what kind of data you're dealing with and how complex it is. For simple settings, SharedPreferences or DataStore might be enough. For more detailed or structured data, Room or SQLite could be better. If you need to share data between different apps, consider using Content Providers.

2. What is a ViewModel, and how does it make managing app lifecycles easier? Can you mention few advantages of using ViewModel for lifecycle management?

ViewModel is an architectural component that manages UI related data in a lifecycle conscious way, allowing data to survive configuration changes such as screen rotations. It helps handle lifecycles more effectively by separating the data from UI controllers like Activities and Fragments.

Benefits of using ViewModel are:

1. Configuration Changes: ViewModel saves your data when your screen changes, so you don't have to reload everything. This makes your app faster and improves user experience.

2. Separation of Concerns: It helps keep your code clean by separating the data layer and UI layer. This makes it easier to work on your app by writing cleaner, more organised code, which is easier to manage and test.

3. What is a ViewModel, and how does it make managing app lifecycles easier? Can you mention few advantages of using ViewModel for lifecycle management?