I've been looking some references to display my value database into android using JSON, but i have a trouble about the keyword to find it, here is all my code to try, please CMIIW, i have put my code and DB into hostinger to make it easy here

php code

dbconfig.php

$servername = "localhost";
$username = "root";
$password = "";
$dbname = "data_kuesioner";

send_data.php

<?php
include 'dbconfig.php';
$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 

$sql = "SELECT * FROM pertanyaan";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while($row[] = $result->fetch_assoc()) {

       $json = json_encode($row);
    }
} else {
    echo "0 results";
}
echo $json;
$conn->close();
?>

android code

MainActivity.java

package flix.yudi.okhttp;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

import java.io.IOException;
import java.util.concurrent.ExecutionException;

import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class MainActivity extends AppCompatActivity {
    private EditText edtText;
    private TextView outputText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        edtText = (EditText) findViewById(R.id.editText1);
        outputText = (TextView) findViewById(R.id.textView1);
    }

    public void downloadUrl(View view) {

        String url = "http://" + edtText.getText().toString();
        OkHttpHandler handler = new OkHttpHandler();
        String result = null;
        try {
            result = handler.execute(url).get();
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ExecutionException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        outputText.append(result + "
");
    }
}

OkHttpHandler.java

package flix.yudi.okhttp;
import android.os.AsyncTask;

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;


public class OkHttpHandler extends AsyncTask<String, Void, String> {

    OkHttpClient client = new OkHttpClient();
    @Override
    protected String doInBackground(String... params) {
        Request.Builder builder = new Request.Builder();
        builder.url(params[0]);
        Request request = builder.build();
        try {
            Response response = client.newCall(request).execute();
            return response.body().string();
        } catch (Exception e) {
        }
        return null;
    }
}

but when i run the program, the app display another interface below

Your url is returning "text/html" you may try put this header in your send_data.php to change the return to json.

header('Content-Type: application/json; charset=utf-8');