Integrating APIs into Android Apps

Integrating APIs into Android Apps

APIs (Application Programming Interfaces) allow your app to interact with external servers to fetch dynamic data such as weather information, news updates, or user profiles. In this tutorial, we’ll integrate a REST API into an Android app using **Retrofit**, a type-safe HTTP client for Android and Java.

1. Add Retrofit to Your Project

First, you need to add Retrofit and its converter to your project's dependencies.

Steps:

• Open your project's `build.gradle` file (Module: app).
• Add the following dependencies inside the `dependencies` block:

dependencies {
    implementation 'com.squareup.retrofit2:retrofit:2.9.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
}

3. Click **Sync Now** to sync the project with the new dependencies.

2. Create the API Interface

Define the endpoints and request methods for the API you want to consume.

Example: Fetching a list of users.

public interface ApiService {
    @GET("users")
    Call<List<User>> getUsers();
}

Explanation:

• @GET("users"): Specifies a GET request to the "users" endpoint.
• Call<List<User>>: Defines the expected response type.

3. Build the Retrofit Instance

Create a Retrofit instance specifying the base URL and the converter factory.

Retrofit retrofit = new Retrofit.Builder()
    .baseUrl("https://jsonplaceholder.typicode.com/")
    .addConverterFactory(GsonConverterFactory.create())
    .build();

ApiService apiService = retrofit.create(ApiService.class);

4. Fetch and Display Data

Make the API call asynchronously and handle the response.

Example:

apiService.getUsers().enqueue(new Callback<List<User>>() {
    @Override
    public void onResponse(Call<List<User>> call, Response<List<User>> response) {
        if (response.isSuccessful()) {
            List<User> users = response.body();
            // TODO: Update UI with the fetched users
        } else {
            // TODO: Handle request errors
        }
    }

    @Override
    public void onFailure(Call<List<User>> call, Throwable t) {
        // TODO: Handle call failure
    }
});

Explanation:

• enqueue: Executes the request asynchronously.
• onResponse: Called when a response is received.
• onFailure: Called when the request fails.

5. Define the User Model

Create a `User` class that matches the JSON structure of the API response.

public class User {
    private int id;
    private String name;
    private String username;
    private String email;

    // Getters and Setters
    public int getId() { return id; }
    public void setId(int id) { this.id = id; }

    public String getName() { return name; }
    public void setName(String name) { this.name = name; }

    public String getUsername() { return username; }
    public void setUsername(String username) { this.username = username; }

    public String getEmail() { return email; }
    public void setEmail(String email) { this.email = email; }
}

Conclusion: Integrating APIs into your Android app using Retrofit allows you to fetch and display dynamic data seamlessly. By following the steps outlined above, you can connect your app to various external services, enhancing its functionality and user experience. Experiment with different APIs to add diverse features to your app!