编写简单登陆和注册功能的demo时遇到的问题

public class RegisterActivity extends AppCompatActivity {

    private MyDatabaseHelper dbHelper;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.register);
        dbHelper = new MyDatabaseHelper(this, "UserStore.db", null, 1);
        Button okButton = (Button)findViewById(R.id.ok);

        okButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                ContentValues values = new ContentValues();
                EditText registerAccount = (EditText)findViewById(R.id.register_account);
                EditText registerPassword = (EditText)findViewById(R.id.register_password);
                String username = registerAccount.getText().toString();
                String password = registerPassword.getText().toString();
                if (!((username.equals("")) || (password.equals("")))) {
                    values.put("name", username);
                    values.put("password", password);
                    db.insert("User", null, values);
                    Toast.makeText(RegisterActivity.this, "注册成功", Toast.LENGTH_SHORT).show();
                    Intent intent = new Intent(RegisterActivity.this, LoginActivity.class);
                    startActivity(intent);
                } else {
                    Toast.makeText(RegisterActivity.this, "用户名或密码不能为空", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}