使用接口将数据从活动传递到片段

public interface DataTransferInterface {
    void onDataTransfer(String data);
}

public class MainActivity extends AppCompatActivity implements DataTransferInterface {
    // ...

    @Override
    public void onDataTransfer(String data) {
        // 处理传递过来的数据
    }
}

public class MyFragment extends Fragment {
    private DataTransferInterface dataTransferInterface;

    // ...

    @Override
    public void onAttach(@NonNull Context context) {
        super.onAttach(context);
        if (context instanceof DataTransferInterface) {
            dataTransferInterface = (DataTransferInterface) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement DataTransferInterface");
        }
    }

    // ...

    private void sendDataToActivity(String data) {
        dataTransferInterface.onDataTransfer(data);
    }
}

public class MainActivity extends AppCompatActivity implements DataTransferInterface {
    // ...

    private void sendDataToFragment(String data) {
        MyFragment fragment = (MyFragment) getSupportFragmentManager().findFragmentById(R.id.fragment_container);
        if (fragment != null) {
            fragment.sendDataToActivity(data);
        }
    }
}