Logueo y contraseña de usuario.

 public void Ingresar(View view){

    AdminBD admin = new AdminBD(this, "BaseDatos", null, 1);
    SQLiteDatabase BaseDatos= admin.getWritableDatabase();
    String cedula = etCedula.getText().toString();
    String contrasenia = etContrasena.getText().toString();

    if(!cedula.isEmpty() && !contrasenia.isEmpty()){

        //verificar que el usuario ponga los datos correctos
        String query = "SELECT * FROM usuarios WHERE cedula = '" + cedula + "' AND contrasenia = '" + contrasenia + "'";
        Cursor fila= BaseDatos.rawQuery(query, null);
       if(fila.moveToFirst()){
            Toast.makeText(this, "Bienvenido :) ", Toast.LENGTH_SHORT).show();
           SharedPreferences sharedPreferences = getSharedPreferences("MiSharedPreferences", Context.MODE_PRIVATE);
           SharedPreferences.Editor editor = sharedPreferences.edit();
           editor.putString("cedula", cedula);
           editor.apply();
            Intent intent= new Intent(this, Menu.class);
            startActivity(intent);

        }else{
            Toast.makeText(this, "Contraseña o cedula incorrectas", Toast.LENGTH_LONG).show();
        }
        etCedula.setText("");
        etContrasena.setText("");

    }

}