Retrieve Data From MySQL Database in Android

<?php

if($_SERVER['REQUEST_METHOD']=='GET'){

$id  = $_GET['id'];

require_once('dbConnect.php');

$sql = "SELECT * FROM colleges WHERE id='".$id."'";

$r = mysqli_query($con,$sql);

$res = mysqli_fetch_array($r);

$result = array();

array_push($result,array(
"name"=>$res['name'],
"address"=>$res['address'],
"vc"=>$res['vicechancellor']
)
);

echo json_encode(array("result"=>$result));

mysqli_close($con);

}

dbConnect.php page code

<?php
define('HOST','localhost');
define('USER','root');
define('PASS','');
define('DB','androiddb');

$con = mysqli_connect(HOST,USER,PASS,DB) or die('Unable to Connect');

Creating a new Android Project

 Add  app 

<div id="inner-editor"> <br class="Apple-interchange-newline">compile 'com.mcxiaoke.volley:library-aar:1.0.0'</div>

1	compile 'com.mcxiaoke.volley:library-aar:1.0.0'

• Now create a new Java class in your package. I created Config.java. Here we will declare some important constants.

package net.simplifiedcoding.gettingspecificdata;

public class Config {

    public static final String DATA_URL = "http://192.168.94.1/Android/College/getData.php?id=";

    public static final String KEY_NAME = "name";

    public static final String KEY_ADDRESS = "address";

    public static final String KEY_VC = "vc";

    public static final String JSON_ARRAY = "result";

}

• For creating the above layout you can use the following xml 

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"

    android:orientation="vertical"

    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

    <LinearLayout

        android:orientation="horizontal"

        android:layout_width="match_parent"

        android:layout_height="wrap_content">

        <EditText

            android:id="@+id/editTextId"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_weight="1"/>

        <Button

            android:id="@+id/buttonGet"

            android:text="Get"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content" />

    </LinearLayout>

    <TextView

        android:id="@+id/textViewResult"

        android:layout_width="fill_parent"

        android:layout_height="fill_parent" />

</LinearLayout>

MAINACtivite.java

package net.simplifiedcoding.gettingspecificdata;

import android.app.ProgressDialog;

import android.os.Bundle;

import android.support.v7.app.AppCompatActivity;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;

import android.widget.Toast;

import com.android.volley.RequestQueue;

import com.android.volley.Response;

import com.android.volley.VolleyError;

import com.android.volley.toolbox.StringRequest;

import com.android.volley.toolbox.Volley;

import org.json.JSONArray;

import org.json.JSONException;

import org.json.JSONObject;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private EditText editTextId;

    private Button buttonGet;

    private TextView textViewResult;

    private ProgressDialog loading;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        editTextId = (EditText) findViewById(R.id.editTextId);

        buttonGet = (Button) findViewById(R.id.buttonGet);

        textViewResult = (TextView) findViewById(R.id.textViewResult);

        buttonGet.setOnClickListener(this);

    }

    private void getData() {

        String id = editTextId.getText().toString().trim();

        if (id.equals("")) {

            Toast.makeText(this, "Please enter an id", Toast.LENGTH_LONG).show();

            return;

        }

        loading = ProgressDialog.show(this,"Please wait...","Fetching...",false,false);

        String url = Config.DATA_URL+editTextId.getText().toString().trim();

        StringRequest stringRequest = new StringRequest(url, new Response.Listener<String>() {

            @Override

            public void onResponse(String response) {

                loading.dismiss();

                showJSON(response);

            }

        },

        new Response.ErrorListener() {

            @Override

            public void onErrorResponse(VolleyError error) {

                Toast.makeText(MainActivity.this,error.getMessage().toString(),Toast.LENGTH_LONG).show();

            }

        });

        RequestQueue requestQueue = Volley.newRequestQueue(this);

        requestQueue.add(stringRequest);

    }

    private void showJSON(String response){

        String name="";

        String address="";

        String vc = "";

        try {

            JSONObject jsonObject = new JSONObject(response);

            JSONArray result = jsonObject.getJSONArray(Config.JSON_ARRAY);

            JSONObject collegeData = result.getJSONObject(0);

            name = collegeData.getString(Config.KEY_NAME);

            address = collegeData.getString(Config.KEY_ADDRESS);

            vc = collegeData.getString(Config.KEY_VC);

        } catch (JSONException e) {

            e.printStackTrace();

        }

        textViewResult.setText("Name:\t"+name+"\nAddress:\t" +address+ "\nVice Chancellor:\t"+ vc);

    }

    @Override

    public void onClick(View v) {

        getData();

    }

}