JSON Parsing Using Retrofit

What is Retrofit?

Retrofit is Rest Client used for Android to upload and retrieve JSON. It is developed by Square.

Step 1

For using retrofit in your app we need to add a library dependency in Module:app gradle.

compile 'com.squareup.retrofit:retrofit:1.9.0'

Below is the example url that is needed to be parsed.

http://dummyjson.890m.com/getcontacts.php

In Retrofit we just break the url in parts we need to exclude the root url in our case it is http://dummyjson.890m.com/ and second part of the url is /getcontacts.php which we need to pass in the interface.

Step 2

Give internet permmission in the manifest

<uses-permission android:name="android.permission.INTERNET"/>

Step 3

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="eazy.mysqliteblog.MainActivity">

    <ListView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/data"></ListView>

</LinearLayout>

Step 4

Create an interface where we need to pass the second part of the url.

DummyApi.java

import retrofit.Callback;
import retrofit.client.Response;
import retrofit.http.GET;

/**
 * Created by Administrator on 07-06-2017.
 */

public interface DummyApi {

    @GET("/getcontacts.php")
    public void getAllData(Callback<Response> responseCallback);
}

Step 5

MainActivity.java

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;

import retrofit.Callback;
import retrofit.RestAdapter;
import retrofit.RetrofitError;
import retrofit.client.Response;

public class MainActivity extends AppCompatActivity {


   ListView listView;
    ArrayList al=new ArrayList();
    StringBuilder stringBuilder=new StringBuilder();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        listView= (ListView) findViewById(R.id.data);


        RestAdapter restAdapter=new RestAdapter.Builder().setEndpoint("http://dummyjson.890m.com/").build();
        DummyApi dummyApi=restAdapter.create(DummyApi.class);
        dummyApi.getAllData(new Callback<Response>() {
            @Override
            public void success(Response response, Response response2) {

                try {
                    BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(response.getBody().in()));
String line;
                    while ((line= bufferedReader.readLine())!=null){
stringBuilder.append(line);

                    }

                    JSONArray jsonArray=new JSONArray(String.valueOf(stringBuilder));
                    for (int i=0;i<jsonArray.length();i++){
                        JSONObject jsonObject=jsonArray.getJSONObject(i);
                        String name=jsonObject.getString("name");
                        String phone=jsonObject.getString("phone");
                        al.add(name+" "+phone);




                    }
                    listView.setAdapter(new ArrayAdapter(MainActivity.this,android.R.layout.simple_list_item_1,al));



                } catch (IOException e) {
                    e.printStackTrace();
                } catch (JSONException e) {
                    e.printStackTrace();
                }


            }

            @Override
            public void failure(RetrofitError error) {

            }
        });
    }

}