How to use a Volley Library to parse a JSON in android App?

AndroidApps/ApplicationsMobile Development

This example demonstrates how do I use a volley Library to parse a JSON in android app.

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:padding="16sp"
   tools:context=".MainActivity">
   <TextView
      android:id="@+id/textViewResult"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:textColor="@android:color/black"
      android:textSize="20sp" />
   <Button
      android:id="@+id/btnParse"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:layout_alignParentBottom="true"
      android:layout_marginBottom="20sp"
      android:text="Parse JSON"/>
</RelativeLayout>

Step 3 – To create a JsonArray, go to http://myjson.com/ create your own JsonArray, for example, refer the code below.

{
   "employees": [
      {
         "firstname": "Niyaz",
         "age": 30,
         "mail": "niyaz3444@gmail.com"
      },
      {
         "firstname": "Mashu",
         "age": 25,
         "mail": "mashu123@gmail.com"
      },
      {
         "firstname": "Rahul",
         "age": 22,
         "mail": "rahul@gmail.com"
      },
      {
         "firstname": "Azhar",
         "age": 40,
         "mail": "azhar0987@gmail.com"
      },
      {
         "firstname": "Aachu",
         "age": 32,
         "mail": "aachu@gmail.com"
      }
   ]
}

URL to access JSON directly: https://api.myjson.com/bins/xbspb, copy and paste the JSON url in the MainActivity.java.

Step 4 − Add the following code to src/MainActivity.java

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
public class MainActivity extends AppCompatActivity {
   private TextView textView;
   private RequestQueue requestQueue;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      textView = findViewById(R.id.textViewResult);
      Button buttonParse = findViewById(R.id.btnParse);
      requestQueue = Volley.newRequestQueue(this);
      buttonParse.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            jsonParse();
         }  
      });
   }
   private void jsonParse() {
      String url = "https://api.myjson.com/bins/xbspb";
      JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
         @Override
         public void onResponse(JSONObject response) {
            try {
               JSONArray jsonArray = response.getJSONArray("employees");
               for (int i = 0; i < jsonArray.length(); i++) {
                  JSONObject employee = jsonArray.getJSONObject(i);
                  String firstName = employee.getString("firstname");
                  int age = employee.getInt("age");
                  String mail = employee.getString("mail");
                  textView.append(firstName + ", " + String.valueOf(age) + ", " + mail +"\n\n");
               }
            } catch (JSONException e) {
               e.printStackTrace();
            }
         }
      }, new Response.ErrorListener() {
         @Override
         public void onErrorResponse(VolleyError error) {
            error.printStackTrace();
         }
      });
      requestQueue.add(request);
   }
}

Step 4 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="app.com.sample">
   <uses-permission android:name="android.permission.INTERNET"/>
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click Run Play Icon icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen –

Click here to download the project code.

raja
Published on 05-Sep-2019 10:19:18
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