<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.nsu.visitorsys">
    <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/AppTheme"
        android:usesCleartextTraffic="true">
        <activity android:name=".loginactivity">
            <intent-filter >
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".menuactivity">
        </activity>
    </application>
</manifest>

--inside loginactivity
--declarations
public static final int CONNECTION_TIMEOUT=10000;
public static final int READ_TIMEOUT=150000;


--put this inside loginactivity, inside the class ,outside the oncreate
--change the ip address as well in the below code


private class AsyncLogin extends AsyncTask<String, String, String>
    {
        ProgressDialog pdLoading = new ProgressDialog(loginactivity.this);
        HttpURLConnection conn;
        URL url = null;

        @Override
        protected void onPreExecute()
        {
            super.onPreExecute();
            pdLoading.setMessage("\tLoading...");
            pdLoading.setCancelable(false);
            pdLoading.show();
        }
        @Override
        protected String doInBackground(String... params)
        {
            try
            {
                url = new URL("http://172.25.101.48/NUSVisitorWeb/login.php");
            }
            catch (MalformedURLException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
                return "exception";
            }
            try
            {
                conn = (HttpURLConnection)url.openConnection();
                conn.setReadTimeout(READ_TIMEOUT);
                conn.setConnectTimeout(CONNECTION_TIMEOUT);
                conn.setRequestMethod("POST");
                conn.setDoInput(true);
                conn.setDoOutput(true);
                Uri.Builder builder = new Uri.Builder()
                        .appendQueryParameter("username", params[0])
                        .appendQueryParameter("password", params[1]);
                String query = builder.build().getEncodedQuery();
                OutputStream os = conn.getOutputStream();
                BufferedWriter writer = new BufferedWriter(
                        new OutputStreamWriter(os, "UTF-8"));
                writer.write(query);
                writer.flush();
                writer.close();
                os.close();
                conn.connect();
            }
            catch (IOException e1)
            {
                e1.printStackTrace();
                return "exception";
            }
            try
            {
                int response_code = conn.getResponseCode();
                if (response_code == HttpURLConnection.HTTP_OK)
                {
                    InputStream input = conn.getInputStream();
                    BufferedReader reader = new BufferedReader(new InputStreamReader(input));
                    StringBuilder result = new StringBuilder();
                    String line;

                    while ((line = reader.readLine()) != null)
                    {
                        result.append(line);
                    }

                    return(result.toString());
                }
                else
                {
                    return("unsuccessful");
                }

            } catch (IOException e)
            {
                e.printStackTrace();
                return "exception";
            }
            finally {
                conn.disconnect();
            }
        }
        @Override
        protected void onPostExecute(String result)
        {
            try
            {
                JSONObject json=new JSONObject(result);
                if(json.getString("status").equals("true"))
                {

                    Toast.makeText(loginactivity.this, "Login Success...", Toast.LENGTH_LONG).show();
                    Intent intent = new Intent(loginactivity.this,menuactivity.class);
                    startActivity(intent);
                    loginactivity.this.finish();
                }
                else if(json.getString("status").equals("false"))
                {
                    Toast.makeText(loginactivity.this, "Invalid username or password", Toast.LENGTH_LONG).show();
                }
                else
                {
                    Toast.makeText(loginactivity.this, "Please check server connection", Toast.LENGTH_LONG).show();
                }
            }
            catch (JSONException e)
            {
                e.printStackTrace();
            }
        }
    }