Volley Android - Java

Volley is an HTTP library developed by Google for Android. It provides a simple and efficient way to send and receive network requests. Volley is designed to make networking tasks easier and faster, while also taking care of some common issues that developers face when dealing with network requests.

Features

Volley has the following features:

• Easy to use API
• Request prioritization
• Automatic request retry
• Memory and disk caching
• Request cancellation
• HTTPS support
• Optional GZIP compression
• Multiple concurrent network connections

Getting started

To use Volley in your Android project, you need to add the following dependency to your build.gradle file:

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

Once you have added the dependency, you can start using Volley in your code.

Sending a network request

To send a network request using Volley, you need to create a RequestQueue instance and add your request to it. Here's an example:

// Instantiate the RequestQueue.
RequestQueue queue = Volley.newRequestQueue(this);

// Request a string response from the provided URL.
StringRequest stringRequest = new StringRequest(Request.Method.GET, url,
        new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                // Display the response string.
                textView.setText(response);
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                // Display an error message.
                textView.setText("That didn't work!");
            }
        });

// Add the request to the RequestQueue.
queue.add(stringRequest);

In this example, we create a StringRequest object that performs a GET request to the specified URL. We also provide a response listener and an error listener to handle the response and error, respectively. Finally, we add the request to the RequestQueue.

Handling JSON responses

Volley also provides support for handling JSON responses. Here's an example:

// Instantiate the RequestQueue.
RequestQueue queue = Volley.newRequestQueue(this);

// Create a new JSONObject request.
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, url, null,
        new Response.Listener<JSONObject>() {
            @Override
            public void onResponse(JSONObject response) {
                try {
                    // Parse the JSON response.
                    String name = response.getString("name");
                    int age = response.getInt("age");

                    // Display the parsed data.
                    textView.setText("Name: " + name + "\n" + "Age: " + age);
                } catch (JSONException e) {
                    // Display an error message.
                    textView.setText("Error parsing JSON!");
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                // Display an error message.
                textView.setText("That didn't work!");
            }
        });

// Add the request to the RequestQueue.
queue.add(jsonObjectRequest);

In this example, we create a JsonObjectRequest object that performs a GET request to the specified URL and expects a JSON response. We also provide a response listener and an error listener to handle the response and error, respectively. Finally, we add the request to the RequestQueue.

Conclusion

Volley is a powerful and easy-to-use HTTP library for Android. It simplifies the process of sending and receiving network requests, and provides a number of useful features. Whether you're building a simple app that needs to interact with a web API, or a complex app that needs to manage multiple network requests, Volley can help you get the job done.