E/AndroidRuntime: FATAL EXCEPTION: main
              Process: tj.ttu.ttu, PID: 15033
              java.lang.IllegalArgumentException: Expected receiver of type tj.ttu.ttu.login, but got android.view.ContextThemeWrapper
                  at java.lang.reflect.Method.invoke(Native Method)
                  at android.view.View$DeclaredOnClickListener.onClick(View.java:4735)
                  at android.view.View.performClick(View.java:5697)
                  at android.widget.TextView.performClick(TextView.java:10826)
                  at android.view.View$PerformClick.run(View.java:22526)
                  at android.os.Handler.handleCallback(Handler.java:739)
                  at android.os.Handler.dispatchMessage(Handler.java:95)
                  at android.os.Looper.loop(Looper.java:158)
                  at android.app.ActivityThread.main(ActivityThread.java:7224)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)

package tj.ttu.ttu;

import android.app.AlertDialog;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.ConnectivityManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;


public class login extends AppCompatActivity {
EditText pwd, lgn;
AlertDialog alertDialogw;
String FileName = "lgn_pwd";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);
    pwd = (EditText) findViewById(R.id.pwd);
    lgn = (EditText) findViewById(R.id.lgn);




}
class background_worker extends AsyncTask<String, Void, String> {
    Context context;
    AlertDialog alertDialog;


    background_worker(Context ctx) {
        context = ctx;
    }

    @Override
    public String doInBackground(String... params) {
        String type = params[0];
        String login_url = "http://77.95.1.234/api/v1/index.php";

        if (type.equals("login")) {
            try {
                String username = params[1];
                String password = params[2];
                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 post_data = URLEncoder.encode("username", "UTF-8") + "=" + URLEncoder.encode(username, "UTF-8") + "&"
                        + URLEncoder.encode("password", "UTF-8") + "=" + URLEncoder.encode(password, "UTF-8")+"&"
                        + URLEncoder.encode("route", "UTF-8") + "=" + URLEncoder.encode("auth", "UTF-8")+"&"
                        + URLEncoder.encode("operation", "UTF-8") + "=" + URLEncoder.encode("login", "UTF-8");
                bufferedWriter.write(post_data);
                bufferedWriter.flush();
                bufferedWriter.close();
                outputStream.close();
                InputStream inputStream = httpURLConnection.getInputStream();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
                String result = "";
                String line = "";
                while ((line = bufferedReader.readLine()) != null) {

                    result += line;
                }
                bufferedReader.close();
                inputStream.close();
                httpURLConnection.disconnect();
                return result;
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }
    @Override
    protected void onPreExecute() {
        alertDialog = new AlertDialog.Builder(context).create();
        alertDialog.setTitle("Статус входа");
    }

    @Override
    public void onPostExecute(String result) {
        JSONObject dataJsonObj = null;
String replace="";
String token="", error ="",message="";
        try {
            dataJsonObj = new JSONObject(result);
          //  JSONArray data = dataJsonObj.getJSONArray("data");

            error = dataJsonObj.getString("error");
            if (error == "true"){
                message = dataJsonObj.getString("message");
                alertDialog.setMessage(message);
                alertDialog.show();
            }else{
                JSONObject secondFriend = dataJsonObj.getJSONObject("data");
                token = secondFriend.getString("token");
                saveFile();

                Intent i = new Intent(login.this, home.class);
                i.putExtra("token", token);
                startActivity(i);
            //alertDialog.setMessage(token);
            }
        } catch (JSONException e) {
            e.printStackTrace();
            Toast.makeText(login.this, "Ошибка"+e, Toast.LENGTH_SHORT).show();
            alertDialog.setMessage("оШИБКА: "+e);

        }





    }

    @Override
    protected void onProgressUpdate(Void... values) {
        super.onProgressUpdate(values);
    }
}
public void signin (View v){
    String loginn = lgn.getText().toString();
    String passwords = pwd.getText().toString();
    alertDialogw = new AlertDialog.Builder(this).create();
    alertDialogw.setTitle("Оповещение");
    String type = "login";
    if (loginn.matches("") | passwords.matches("")) {

        Toast.makeText(login.this, "Поле логин или пароль пусто!", Toast.LENGTH_SHORT).show();

    }else if(loginn.matches("07-5963/15" )){

        Toast.makeText(login.this, "Пользователь "+loginn+" заблокирован!", Toast.LENGTH_SHORT).show();
    }else if (loginn.matches("07-5952/15")) {
        Toast.makeText(login.this, "Пользователь "+loginn+" заблокирован!", Toast.LENGTH_SHORT).show();
    }else{
        if (!isOnline()) {
            runOnUiThread(new Runnable() {
                public void run() {
                    Toast.makeText(login.this, "Нет соединения с интернетом!", Toast.LENGTH_LONG).show();

                }
            });
        } else {
            background_worker backgroundWorker = new background_worker(this);
            backgroundWorker.execute(type, loginn, passwords);
        }
    }

}
protected boolean isOnline() {
    String cs = Context.CONNECTIVITY_SERVICE;
    ConnectivityManager cm = (ConnectivityManager)
            getSystemService(cs);
    if (cm.getActiveNetworkInfo() == null) {
        return false;
    } else { return true; }
}
private void saveFile(){
    String strLogin = lgn.getText().toString();
    String strPassword = pwd.getText().toString();
    SharedPreferences sharedPreferences = getSharedPreferences(FileName,Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putString("login", strLogin);
    editor.putString("password", strPassword);
    editor.commit();


}