What is causing the errors in the following java code

Question

I have implemented a method to validate a user against an SQLite DB but the program keeps throwing an error when the login button is clicked the error codes follow

2019-04-15 21:38:27.455 4601-4601/com.example.mymedicare E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.mymedicare, PID: 4601 android.database.sqlite.SQLiteException: no such column: Brad (code 1): , while compiling: SELECT * FROM users WHERE Brad =? AND Brad1994 =? at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method) at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889) at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500) at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588) at android.database.sqlite.SQLiteProgram.(SQLiteProgram.java:58) at android.database.sqlite.SQLiteQuery.(SQLiteQuery.java:37) at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44) at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1318) at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1257) at com.example.mymedicare.MyDBHelper.checkLogin(MyDBHelper.java:96)

I have tried reading the error log but can't find any serious errors my methods will be shown below

  // This is my check login method in mydbhelper   

   public boolean checkLogin(String username, String password) {
    SQLiteDatabase db = this.getWritableDatabase();

    String s;
    Cursor c = db.rawQuery("SELECT * FROM users WHERE " + username + " =? AND " + password + " =?", null);

    if (c.getCount() <= 0) {
        c.close();
        db.close();
        return false;
    } else {
        c.close();
        db.close();
        return true;
    }
}


   //This is LoggingIn activity where I have tried to implement the above 
   method 

   public class LoggingIn extends AppCompatActivity {

//defines page objects
private Button SignIn;
private EditText Usernames;
private EditText Passwords;
private MyDBHelper db;

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

    //Finds objects by ID
     //edit text to string
    Usernames = (EditText) findViewById(R.id.Usernames);

    Passwords = (EditText) findViewById(R.id.Passwords);


    Button SignIn = (Button) findViewById(R.id.SignIn);
    db = new MyDBHelper(this);

    SignIn.setOnClickListener(new Button.OnClickListener() {
        @Override
        public void onClick(View v) {
            Boolean validUser = 
     db.checkLogin(Usernames.getText().toString(), 
     Passwords.getText().toString());

            if (validUser == true) {
                Intent i = new Intent(getApplicationContext(), 
                HomePage.class);
                startActivity(i);
            } else {
                Toast.makeText(getApplicationContext(), "Invalid login", 
                Toast.LENGTH_SHORT).show();
            }

        }
    });
}
}

Answer 1

You are passing the parameters username and password as column names.
The correct way is:

Cursor c = db.rawQuery(
    "SELECT * FROM users WHERE usenamecolumn = ? AND passwordcolumn = ?", 
     new String[] {username, password});

Change usenamecolumn and passwordcolumn to your table's column names for username and password.