public class LoginActivity extends BaseActivity {

    @InjectView(R.id.username)
    EditText username;

    @InjectView(R.id.password)
    EditText password;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    setContentView(R.layout.login);

        username = (EditText) findViewById(R.id.username);
        password = (EditText) findViewById(R.id.password);

    }
}

public abstract class BaseActivity extends FragmentActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        ButterKnife.inject(this);
    }
}