package com.example.examinationportal;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.graphics.Color;
import android.net.Uri;
import android.os.AsyncTask;
import android.provider.Settings;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.app.IntentService;
import android.app.PendingIntent;
import org.apache.http.NameValuePair;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.io.InputStream;
public class MainActivity extends AppCompatActivity {
    public String message = "";
    SQLiteDatabase myDB = null;
    public String TableName = "Users";
    public String Data;
    public String responseData;
    public String username;
    public  String password;
    public String data;
    public String query;
    TextView statusBar, titleLogin;
    EditText un, pw;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // Get user defined values
        un = (EditText) findViewById(R.id.editTextUsername);//username field
        pw = (EditText) findViewById(R.id.editTextPassword);//password field
        username = un.getText().toString();//convert username and password to string and parse
        password = pw.getText().toString();//them to variables
        //initialize the status bar textview control
        statusBar = (TextView) findViewById(R.id.textViewStatusMsg);
        titleLogin = (TextView) findViewById(R.id.textViewLogin);//title text of this UI
    }

private   class  GetText  extends AsyncTask<Void, Void, Void> {//} throws UnsupportedEncodingException {
        @Override
        protected Void doInBackground(Void...params){
            BufferedReader reader = null;
            // Send data
            try {
                // Defined URL  where to send data
                URL url = new URL("http://www.naomiedify.com/school/test/login2.php");
                //URLConnection con = url.openConnection();
                HttpURLConnection con = (HttpURLConnection) url.openConnection();
                con.setRequestProperty("Accept-Charset", "UTF-8");
                con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
                con.setRequestMethod("POST");
                con.setReadTimeout(10000);
                con.setConnectTimeout(15000);

//this method returns empty strings
                query = URLEncoder.encode("txtUserName" +username,"UTF-8");
                query += URLEncoder.encode("&txtPassword" +password, "UTF-8");
                query += URLEncoder.encode("&cmbType=Aptitude Test", "UTF-8");

//this method also returns empty strings
Uri.Builder builder = new Uri.Builder()
                        .appendQueryParameter("txtUserName", username)
                        .appendQueryParameter("txtPassword", password)
                        .appendQueryParameter("cmbType", "Aptitude Test");
                query = builder.build().getEncodedQuery();

con.setDoOutput(true);
                OutputStreamWriter wr = new OutputStreamWriter(con.getOutputStream());

                wr.write( query );
                wr.flush();
                wr.close();

reader = new BufferedReader(new InputStreamReader(con.getInputStream()));
                StringBuilder sb = new StringBuilder();
                String line;

while((line = reader.readLine()) != null) {

sb.append(line + "n");
                    Log.d("Response: ", "> " + line);
                }
                reader.close();
                responseData = sb.toString();
            }
            catch (MalformedURLException e) {
                e.printStackTrace();
                responseData = e.toString();
            }
            catch (IOException e) {
                e.printStackTrace();
                responseData = e.toString();
            }
            return null;
        }

@Override
        protected void onPostExecute(Void result){
            statusBar.setText(responseData);
            super.onPostExecute(result);
        }
    }

public void loginUser(View login) {// Called when the user taps the login button
        Intent intent = new Intent(this, DisplayWelcomeScreen.class);//start the ui

new GetText().execute();
        try{
            //check the login using the post back data
            if (responseData.equals("User Found.")) {
                message = "Welcome"; //message for successful login
                // Show respsonse on activity
                statusBar.setText( responseData  );
                Bundle bundle = new Bundle();//bundle the message and parse it to the next activity
                bundle.putString("dispMsg", message);//bundle the message using the variable dispMsg
                intent.putExtras(bundle);
                startActivity(intent);
            } else {
                message = "Incorrect Username or Password. Try again!";
                statusBar.setTextColor(Color.parseColor("#ff0000"));
                statusBar.setBackgroundColor(Color.parseColor("#d3d3d3"));
                // Show response on activity
                statusBar.setText( responseData  + ": Incorrect Username or Password.");
            }
        }
        catch(Exception ex) {
            statusBar.setText("URL Exeption! "+ex);
        }
    }
}

<?php
$dataComingFrom = substr($_SERVER['HTTP_USER_AGENT'], 0, 7);
//echo $dataComingFrom;

    $con = mysqli_connect($hostname_school,$username_school,"$password_school");//connect to server
    mysqli_select_db($con,$_db);
    if (mysqli_connect_errno()){//if error connecting to server, return error message
        die("Failed to connect to MySQL: " . mysqli_connect_error());

    }else if(!mysqli_select_db($con,$_db)) {//if no error connecting to server, try to select db to see whether it already exists.

        if ($perform = mysqli_query($con,"CREATE DATABASE IF NOT EXISTS $_db")){ //if no db exists on the server, create the db.
            $msg = "Database $_db has been created successfully";
            //echo $msg;
        }else { echo mysqli_errno($con) .": Error creating database: " . mysqli_error($con);}//if it can't create db, return error message

    }else{ //if db was selected, it means the db already exists
        //$data = "You have already created this database!";//return message that db already exists
        //die("$data <br>");//kill the script

        //you can perform the login process here
        //$ip           = preg_replace( '#[^0-9.]#', '', getenv( 'REMOTE_ADDR' ) );
        $username = stripslashes( str_replace( "[^A-Z a-z0-9]", "", $_POST[ 'txtUserName' ] ) );
        $plainPass = stripslashes( str_replace( "[^A-Z a-z0-9]", "", $_POST[ 'txtPassword' ] ) );
        $password   = strrev(md5($plainPass));

        //run the query to search for the username and password for a match
        //$query = "SELECT * FROM $tbl_name WHERE first_name = '$un' AND password = '$pw'";

        if(empty($username) or empty($plainPass)){die("Empty Strings Parsed.");}

    $user = mysqli_query($con,"SELECT * FROM ap_student WHERE AS_Email ='".$username."' AND AS_Password ='".$password."' AND
    AS_Status ='Confirmed!'") or die("Unable to verify user due to: " . mysqli_error($con));

    //$insert = mysqli_query($con,"UPDATE ap_student SET AS_Password = '".$password."' WHERE AS_Id = 1") or die(mysqli_error($con));

    $result = mysqli_num_rows($user);
    if ($result > 0){$returnedString = "User Found.";}else {$returnedString = "User Not Found";echo $returnedString;}

}
?>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.examinationportal">

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

    <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/Theme.AppCompat.DayNight.DarkActionBar">
        <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>