Volley

Before Retrofit became the default choice, Google published its own HTTP library: Volley. It is older and less actively developed today, but it is still found in plenty of existing Android codebases, so it is worth knowing how to read and maintain, even if you would not necessarily pick it for a brand new project.

Volley was designed for many small, frequent requests – it was historically popular for simple JSON calls because of its built-in request queuing, prioritization, and response caching, all handled for you without extra setup.

Adding the Dependency

dependencies {
    implementation 'com.android.volley:volley:1.2.1'
}

The RequestQueue

Every Volley request is submitted to a RequestQueue – a single central object that manages all outgoing requests for your app, including their priority order, retry policy, and cache. Create one instance and reuse it (a singleton is the common pattern):

// VolleySingleton.java
public class VolleySingleton {
    private static VolleySingleton instance;
    private final RequestQueue requestQueue;

    private VolleySingleton(Context context) {
        requestQueue = Volley.newRequestQueue(context.getApplicationContext());
    }

    public static synchronized VolleySingleton getInstance(Context context) {
        if (instance == null) {
            instance = new VolleySingleton(context);
        }
        return instance;
    }

    public RequestQueue getRequestQueue() {
        return requestQueue;
    }
}

Fetching Recipes with JsonArrayRequest

Unlike Retrofit, which defines endpoints as a separate interface, Volley requests are built directly where you use them, with success and error listeners passed straight into the constructor:

// Inside RecipeListActivity.java
String url = "https://api.recipebox.example.com/recipes";

JsonArrayRequest request = new JsonArrayRequest(
        Request.Method.GET,
        url,
        null,
        new Response.Listener<JSONArray>() {
            @Override
            public void onResponse(JSONArray response) {
                List<Recipe> recipes = parseRecipes(response);
                adapter.setRecipes(recipes);
            }
        },
        new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                showError("Could not load recipes");
            }
        }
);

VolleySingleton.getInstance(this).getRequestQueue().add(request);

A Custom POST with StringRequest

When you need full control over the request body – for example, posting a new recipe as JSON – a StringRequest lets you override getBody() and getBodyContentType() directly:

String url = "https://api.recipebox.example.com/recipes";
String json = new Gson().toJson(newRecipe);

StringRequest request = new StringRequest(
        Request.Method.POST,
        url,
        response -> onRecipeCreated(),
        error -> showError("Could not save recipe")
) {
    @Override
    public byte[] getBody() {
        return json.getBytes(StandardCharsets.UTF_8);
    }

    @Override
    public String getBodyContentType() {
        return "application/json; charset=utf-8";
    }
};

VolleySingleton.getInstance(this).getRequestQueue().add(request);

Volley vs. Retrofit – An Honest Comparison