Question

我通过右键单击我的项目并选择新的＆gt;创建了一个新活动。片段＆gt;空白片段。

这是自动生成的片段。我添加的唯一内容是onCreateView()方法下的行。我还在我要将此片段附加到的活动上实现了onFragmentInteractionListener。我确保在该Activity上实现onFragmentInteraction(...)方法，但将其留空。

这里的问题是什么？

   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);
}

}

这是logcat错误：

    Process: mjj.fling, PID: 8965
java.lang.RuntimeException: Unable to start activity ComponentInfo{mjj.fling/mjj.fling.HowToPlayActivity}: android.view.InflateException: Binary XML file line #19: Error inflating class fragment
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2441)
        at android.app.ActivityThread.access$800(ActivityThread.java:162)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1349)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5431)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:913)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:706)
 Caused by: android.view.InflateException: Binary XML file line #19: Error inflating class fragment
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:763)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:809)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
        at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:402)
        at android.app.Activity.setContentView(Activity.java:2214)
        at mjj.fling.HowToPlayActivity.onCreate(HowToPlayActivity.java:16)
        at android.app.Activity.performCreate(Activity.java:6093)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)



 Caused by: android.app.Fragment$InstantiationException: Trying to instantiate a class mjj.fling.FragmentHowToPlay that is not a Fragment
        at android.app.Fragment.instantiate(Fragment.java:606)
        at android.app.Fragment.instantiate(Fragment.java:582)
        at android.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2108)
        at android.app.Activity.onCreateView(Activity.java:5431)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:733)



 Caused by: java.lang.ClassCastException

对于将片段附加到

的活动，

XML LAYOUT

<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>

Answer 1

您片段扩展android.support.v4.app.Fragment而不是android.app.Fragment - 请参阅导入声明。前者应由支持库中的FragmentActivity（或更好的新AppCompatActivity}使用，而不是常规android.app.Activity。您需要更改其中一个，并且通常与您在整个应用程序中使用的内容保持一致。

无法通过XML将Fragment附加到活动

1 个答案: