How to Start Developing an Android App from Scratch with a Scalable Architecture

Developing an Android application from scratch can be overwhelming, especially when considering scalability. In this article, we will explore how to structure your project with a robust architecture, compare different libraries, and implement core functionalities such as API calls, SQLite persistence, and a simple CRUD UI using Jetpack Compose.

Choosing the Right Architecture

For a scalable Android app, the MVVM (Model-View-ViewModel) architecture is a solid choice. It separates concerns and ensures better testability and maintainability.

Comparison of Architectural Libraries

Making API Calls with Retrofit

Retrofit is a popular library for handling API requests efficiently. Here’s how you can set up a simple API call:

interface ApiService {
    @GET("users/{id}")
    suspend fun getUser(@Path("id") userId: Int): Response<User>
}

object RetrofitInstance {
    private val retrofit = Retrofit.Builder()
        .baseUrl("https://api.example.com/")
        .addConverterFactory(GsonConverterFactory.create())
        .build()

    val api: ApiService by lazy {
        retrofit.create(ApiService::class.java)
    }
}        

Persisting Data with SQLite (Room Library)

Room provides an abstraction layer over SQLite for easier database management.

@Entity
data class User(
    @PrimaryKey val id: Int,
    val name: String,
    val email: String
)

@Dao
interface UserDao {
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    suspend fun insertUser(user: User)

    @Query("SELECT * FROM User WHERE id = :id")
    suspend fun getUserById(id: Int): User?
}

@Database(entities = [User::class], version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun userDao(): UserDao
}        

Building a Simple CRUD UI with Jetpack Compose

Jetpack Compose simplifies UI development. Here’s a basic implementation of a user form:

@Composable
fun UserForm(userDao: UserDao) {
    var name by remember { mutableStateOf("") }
    var email by remember { mutableStateOf("") }

    Column(modifier = Modifier.padding(16.dp)) {
        OutlinedTextField(value = name, onValueChange = { name = it }, label = { Text("Name") })
        OutlinedTextField(value = email, onValueChange = { email = it }, label = { Text("Email") })
        Button(onClick = {
            val user = User(id = Random.nextInt(), name = name, email = email)
            CoroutineScope(Dispatchers.IO).launch { userDao.insertUser(user) }
        }) {
            Text("Save User")
        }
    }
}        

Conclusion

Starting an Android app with a scalable architecture is crucial for long-term success. Using MVVM, Retrofit, Room, and Jetpack Compose ensures efficiency, maintainability, and a smooth development process.

References

• Android Developer Guide
• Room Persistence Library
• Jetpack Compose

Hashtags

#AndroidDevelopment #JetpackCompose #RoomDatabase #Retrofit #MVVM #Kotlin #MobileDevelopment