Sugar ORM - authentification activity

Я делаю класс активити, в котором аутентификация. У меня ошибка:

Failed to read row 3, column -1 from a CursorWindow which has 10 rows, 3 columns. Failed to read row 3, column -1 from a CursorWindow which has 10 rows, 3 columns. .. .. .. Failed to read row 9, column -1 from a CursorWindow which has 10 rows, 3 columns.

Вот код активити:

package com.example.dbapp;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;
import com.orm.SugarContext;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends Activity implements OnClickListener {
    final String LOG_TAG = "myLogs";
    Button btnAdd, btnRead, btnClear;
    Button backToInReg,register;
    EditText etName, etEmail;
    ArrayAdapter<Book> arrayAdapter;
    ListView listView;
    Book  book = new Book();
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnAdd = (Button) findViewById(R.id.log);
        btnAdd.setOnClickListener(this);
        etName = (EditText) findViewById(R.id.login);
        etEmail = (EditText) findViewById(R.id.password);
        register = (Button) findViewById(R.id.reg);
        register.setOnClickListener(this);
        listView = (ListView) findViewById(R.id.listView);
        List<Book> list = Book.listAll(Book.class);
        arrayAdapter = new ArrayAdapter<Book>(MainActivity.this,android.R.layout.simple_list_item_1,list);
        listView.setAdapter(arrayAdapter);
    }
    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.log:
                String login = etName.getText().toString();
                String password = etEmail.getText().toString();
                List<Book> list = Book.listAll(Book.class);
                for(int i = 0;i<list.size();i++){
                    String ds = list.get(i).login;
                    if(list.get(i).login==login && list.get(i).password==password){
                        Intent intent = new Intent(MainActivity.this,Activity_Registration.class);
                        startActivity(intent);
                    }else {
                        Toast.makeText(getApplicationContext(),"Error! Login or password incorrect!",Toast.LENGTH_SHORT).show();
                    }
                }
                break;
            case R.id.reg:
                break;
        }
    }

}

Вопрос: Правильно ли я проверяю логин и пароль с базы данных?