Android 无法通过XML将片段附加到活动

我通过右键单击我的项目并选择new>fragment>blank fragment创建了一个新活动

这是自动生成的片段。我只添加了

onCreateView（）方法下的行。我还对我要附加此片段的活动实现了onFragmentInteractionListener。我确保在该活动上实现
onFragmentInteraction（…）
方法，但将其留空

这里有什么问题

   import android.app.Activity;
import android.net.Uri;
import android.os.Bundle;
import android.text.Html;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.support.v4.app.Fragment;


public class FragmentHowToPlay extends Fragment {
    // TODO: Rename parameter arguments, choose names that match
    // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";

// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;

private OnFragmentInteractionListener mListener;

/**
 * Use this factory method to create a new instance of
 * this fragment using the provided parameters.
 *
 * @param param1 Parameter 1.
 * @param param2 Parameter 2.
 * @return A new instance of fragment FragmentHowToPlay.
 */
// TODO: Rename and change types and number of parameters
public static FragmentHowToPlay newInstance(String param1, String param2) {
    FragmentHowToPlay fragment = new FragmentHowToPlay();
    Bundle args = new Bundle();
    args.putString(ARG_PARAM1, param1);
    args.putString(ARG_PARAM2, param2);
    fragment.setArguments(args);
    return fragment;
}

public FragmentHowToPlay() {
    // Required empty public constructor
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (getArguments() != null) {
        mParam1 = getArguments().getString(ARG_PARAM1);
        mParam2 = getArguments().getString(ARG_PARAM2);
    }
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View v = inflater.inflate(R.layout.fragment_fragment_how_to_play, container, false);

    TextView text1 = (TextView) v.findViewById(R.id.text1);

    text1.setText(Html.fromHtml(getString(R.string.my_text)));


    return v;


}

// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
    if (mListener != null) {
        mListener.onFragmentInteraction(uri);
    }
}

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    try {
        mListener = (OnFragmentInteractionListener) activity;
    } catch (ClassCastException e) {
        throw new ClassCastException(activity.toString()
                + " must implement OnFragmentInteractionListener");
    }
}

@Override
public void onDetach() {
    super.onDetach();
    mListener = null;
}

/**
 * This interface must be implemented by activities that contain this
 * fragment to allow an interaction in this fragment to be communicated
 * to the activity and potentially other fragments contained in that
 * activity.
 * <p/>
 * See the Android Training lesson <a href=
 * "http://developer.android.com/training/basics/fragments/communicating.html"
 * >Communicating with Other Fragments</a> for more information.
 */
public interface OnFragmentInteractionListener {
    // TODO: Update argument type and name
    public void onFragmentInteraction(Uri uri);
}

}

片段所附加到的活动的XML布局

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="mjj.fling.HowToPlayActivity"
android:background="#01051D">

<ScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/scrollView"
    android:layout_alignParentTop="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:layout_marginTop="42dp" >

    <fragment
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:name="mjj.fling.FragmentHowToPlay"
        android:id="@+id/fragment"
        tools:layout="@layout/fragment_fragment_how_to_play" />
</ScrollView>



您使用片段扩展了
android.support.v4.app.fragment
，而不是
android.app.fragment
——请参见导入声明。前者用于支持库中的
FragmentActivity
（或者更好的是新的
AppCompatActivity
），而不是常规的
android.app.Activity
。您需要更改其中一个，并且通常在整个应用程序中使用的内容保持一致。
发布您的布局XmlActual nevermind，我看到了问题您是否建议改为扩展FragmentActivity？好的，我更改了导入和扩展Fragment。没有撞车！
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="mjj.fling.HowToPlayActivity"
android:background="#01051D">

<ScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/scrollView"
    android:layout_alignParentTop="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:layout_marginTop="42dp" >

    <fragment
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:name="mjj.fling.FragmentHowToPlay"
        android:id="@+id/fragment"
        tools:layout="@layout/fragment_fragment_how_to_play" />
</ScrollView>