private EditText editTextUsername, editTextPassword;
private Button buttonLogin;
private ProgressDialog progressDialog;

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







    if(SharedPrefManager.getInstance(this).isLoggedIn()){
        finish();
        startActivity(new Intent(this, AdminGMenuActivity.class));
        return;
    }

    editTextUsername = (EditText) findViewById(R.id.editTextUsername);
    editTextPassword = (EditText) findViewById(R.id.editTextPassword);
    buttonLogin = (Button) findViewById(R.id.buttonLogin);

    progressDialog = new ProgressDialog(this);
    progressDialog.setMessage("Please wait...");

    buttonLogin.setOnClickListener(this);

}

private void userLogin(){
    final String username = editTextUsername.getText().toString().trim();
    final String password = editTextPassword.getText().toString().trim();

    progressDialog.show();

    StringRequest stringRequest = new StringRequest(
            Request.Method.POST,
            Constants.URL_LOGIN,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    progressDialog.dismiss();




                    try {
                        JSONObject obj = new JSONObject(response);
                        if(!obj.getBoolean("error")){
                            SharedPrefManager.getInstance(getApplicationContext())
                                    .userLogin(
                                            obj.getInt("id"),
                                            obj.getString("username"),
                                            obj.getString("email")
                                    );
                            startActivity(new Intent(getApplicationContext(), AdminGMenuActivity.class));
                            finish();
                        }else{
                            Toast.makeText(
                                    getApplicationContext(),
                                    obj.getString("message"),
                                    Toast.LENGTH_LONG
                            ).show();
                        }

                    }

                    catch (JSONException e) {
                        e.printStackTrace();
                    }





                }


            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    progressDialog.dismiss();

                    Toast.makeText(
                            getApplicationContext(),
                           error.getMessage(),
                            Toast.LENGTH_LONG
                    ).show();
                }
            }
    ){
        @Override
        protected Map<String, String> getParams() throws AuthFailureError {
            Map<String, String> params = new HashMap<>();
            params.put("username", username);
            params.put("password", password);
            return params;
        }

    };

    RequestHandler.getInstance(this).addToRequestQueue(stringRequest);
}




@Override
public void onClick(View view) {

    if(view == buttonLogin){
        userLogin();
    }
}