public class MainActivity extends AppCompatActivity {
EditText userName , password;
String res = "toomy";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    userName= (EditText)findViewById(R.id.userName);
    password= (EditText)findViewById(R.id.password);
}

public void login(View view) {
    String name = userName.getText().toString();
    String pass = password.getText().toString();
    String type="login";

    BackgroundTask background= new BackgroundTask(this);
    background.execute(type, name, pass).toString();
}

public class BackgroundTask extends AsyncTask<String,Void ,String> {
    AlertDialog alertDialog ;
    Context ctx;

    BackgroundTask(Context ctx){
        this.ctx=ctx;
    }
    @Override
    protected void onPreExecute(){
        alertDialog= new AlertDialog.Builder(ctx).create();
        alertDialog.setTitle("Login information...");
    }

    @Override
    protected String doInBackground(String... params) {
        String login_url="http://192.168.173.1/loginf.php";
        String method= params[0];
        if(method.equals("login")){
            String name = params[1];
            String password = params[2];
            try {

                URL url= new URL(login_url);
                HttpURLConnection httpURLConnection= (HttpURLConnection) url.openConnection();
                httpURLConnection.setRequestMethod("POST");
                httpURLConnection.setDoOutput(true);
                httpURLConnection.setDoInput(true);
                OutputStream outputStream = httpURLConnection.getOutputStream();
                BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream,"UTF-8"));
                 String data = URLEncoder.encode("name","UTF-8") +"="+ URLEncoder.encode(name,"UTF-8")+"&"+
                        URLEncoder.encode("password","UTF-8")+"="+ URLEncoder.encode(password,"UTF-8");

                bufferedWriter.write(data);
                bufferedWriter.flush();
                bufferedWriter.close();
                outputStream.close();

                InputStream inputStream = httpURLConnection.getInputStream();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"iso-8859-1"));
                String response= "";
                String line= "";
                while ((line= bufferedReader.readLine())!= null){
                    response+= line;
                }
                bufferedReader.close();
                inputStream.close();
                httpURLConnection.disconnect();
                res = response;
                Log.d("hgjh",res);
                return res;
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }//end of if
        return null;
    }//end of method doInBackground

    @Override
    protected void onProgressUpdate(Void... values) {
        super.onProgressUpdate(values);
    }

    @Override
    protected void onPostExecute(String result) {
        if (result.equals("Login success")) {
            Toast.makeText(ctx, result, Toast.LENGTH_LONG).show();
            Intent in = new Intent(getApplicationContext(), Main.class);
            startActivity(in);
            finish();
        }
        else {
            Toast.makeText(ctx, "login faild", Toast.LENGTH_LONG).show();
        }
    }
}//end of class BackgroundTask