Android 致命异常：无法启动活动组件信息

我运行此应用程序时遇到问题，启动后立即崩溃。我在练习碎片，我不知道问题出在哪里。我发布了错误日志和我的代码。谢谢你的帮助：）

RSSFeed活动

package com.example.rssfeed;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class RssfeedActivity extends Activity implements MyListFragment.OnItemSelectedListener{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_rssfeed);
    }

    // if the wizard generated an onCreateOptionsMenu you can delete
    // it, not needed for this tutorial

  @Override
  public void onRssItemSelected(String link) {
    DetailFragment fragment = (DetailFragment) getFragmentManager()
            .findFragmentById(R.id.detailFragment);
        if (fragment != null && fragment.isInLayout()) {
          fragment.setText(link);
        } 
  }

} 

    package com.example.rssfeed;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class DetailFragment extends Fragment {

  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
      Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_rssitem_detail,
        container, false);
    return view;
  }

  public void setText(String item) {
    TextView view = (TextView) getView().findViewById(R.id.detailsText);
    view.setText(item);
  }
} 

MyListFragment

    package com.example.rssfeed;

import android.app.Activity;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

public class MyListFragment extends Fragment {

  private OnItemSelectedListener listener;

  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
      Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_rsslist_overview,
        container, false);
    Button button = (Button) view.findViewById(R.id.button1);
    button.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        updateDetail();
      }
    });
    return view;
  }

  public interface OnItemSelectedListener {
      public void onRssItemSelected(String link);
    }

  @Override
    public void onAttach(Activity activity) {
      super.onAttach(activity);
      if (activity instanceof OnItemSelectedListener) {
        listener = (OnItemSelectedListener) activity;
      } else {
        throw new ClassCastException(activity.toString()
            + " must implemenet MyListFragment.OnItemSelectedListener");
      }
    }


  // May also be triggered from the Activity
  public void updateDetail() {
    // create fake data
    String newTime = String.valueOf(System.currentTimeMillis());
    // Send data to Activity
    listener.onRssItemSelected(newTime);
  }
} 

布局文件

    <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"
    tools:context="${relativePackage}.${activityClass}" >
<fragment
        android:id="@+id/listFragment"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent"
        android:layout_marginTop="?android:attr/actionBarSize"
        class="com.example.android.rssfeed.MyListFragment" ></fragment>
<fragment
        android:id="@+id/detailFragment"
        android:layout_width="0dp"
        android:layout_weight="2"
        android:layout_height="match_parent"
        class="com.example.android.rssfeed.DetailFragment" >
        <!-- Preview: layout=@layout/details -->
    </fragment>
</RelativeLayout>

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/detailsText"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center_horizontal|center_vertical"
        android:layout_marginTop="20dip"
        android:text="Default Text"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:textSize="30dip" />

</LinearLayout>
    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Press to update" />

</LinearLayout>

---

似乎

MyListFragment

和

DetailFragment

是

com.example.rssfeed

包的一部分。因此在

Fragment

中，标记更改

com.example.android.rssfeed.MyListFragment

到

及

到

i、 e.在布局文件中，更改

fragment
        android:id="@+id/listFragment"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent"
        android:layout_marginTop="?android:attr/actionBarSize"
        class="com.example.android.rssfeed.MyListFragment" ></fragment>
<fragment
        android:id="@+id/detailFragment"
        android:layout_width="0dp"
        android:layout_weight="2"
        android:layout_height="match_parent"
        class="com.example.android.rssfeed.DetailFragment" >
        <!-- Preview: layout=@layout/details -->
    </fragment>

片段
android:id=“@+id/listFragment”
android:layout_width=“0dp”
android:layout_weight=“1”
android:layout\u height=“match\u parent”
android:layout_marginTop=“？android:attr/actionBarSize”
class=“com.example.android.rssfeed.MyListFragment”>

到

片段
android:id=“@+id/listFragment”
android:layout_width=“0dp”
android:layout_weight=“1”
android:layout\u height=“match\u parent”
android:layout_marginTop=“？android:attr/actionBarSize”
class=“com.example.rssfeed.MyListFragment”>

com.example.rssfeed.MyListFragment

com.example.android.rssfeed.DetailFragment

com.example.rssfeed.DetailFragment

fragment
        android:id="@+id/listFragment"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent"
        android:layout_marginTop="?android:attr/actionBarSize"
        class="com.example.android.rssfeed.MyListFragment" ></fragment>
<fragment
        android:id="@+id/detailFragment"
        android:layout_width="0dp"
        android:layout_weight="2"
        android:layout_height="match_parent"
        class="com.example.android.rssfeed.DetailFragment" >
        <!-- Preview: layout=@layout/details -->
    </fragment>

fragment
        android:id="@+id/listFragment"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent"
        android:layout_marginTop="?android:attr/actionBarSize"
        class="com.example.rssfeed.MyListFragment" ></fragment>
<fragment
        android:id="@+id/detailFragment"
        android:layout_width="0dp"
        android:layout_weight="2"
        android:layout_height="match_parent"
        class="com.example.rssfeed.DetailFragment" >
        <!-- Preview: layout=@layout/details -->
    </fragment>