Question

我的活动有一个列表视图，它使用列表适配器来显示元素。当点击片段上有文本的元素时，应创建具有播放按钮，搜索栏和媒体播放器的片段。但是，当我的活动被调用时，我收到此错误。

第14行是list_songs是有的 “片段”开始标记

> 02-26 02:01:27.625: E/AndroidRuntime(2419): FATAL EXCEPTION: main
> 02-26 02:01:27.625: E/AndroidRuntime(2419):
> java.lang.RuntimeException: Unable to start activity
> ComponentInfo{com.songs/com.songs.display.DisplaysongDetails}:
> android.view.InflateException: Binary XML file line #14: Error
> inflating class fragment

活动的代码是

public class DisplaysongDetails extends ListActivity {
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    this.setContentView(R.layout.list_songs);
    setListAdapter(new ArrayAdapter<String>(this, R.layout.row,songDetails));
    ListView listView = (ListView) this.findViewById(android.R.id.list);//getListView();
    listView.setTextFilterEnabled(true);
    listView.setOnItemClickListener(new OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
            String name = ((TextView) view).getText().toString();
            if (name=="Play")
            {
                PlayerFragment frag = (PlayerFragment) getFragmentManager().findFragmentById(R.id.player_fragment);
                if (frag == null) {
                    FragmentTransaction ft = getFragmentManager().beginTransaction();
                    ft.add(R.id.player_fragment, new PlayerFragment());
                    ft.commit(); 
                }}
        }
    });

}}

list_songs.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#FFFFFF">
<ListView
    android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" />   
<fragment
    android:id="@+id/player_fragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    class="com.songs.PlayerFragment" />     
</LinearLayout>

片段类是：

public class PlayerFragment extends Fragment implements  OnTouchListener, OnCompletionListener, OnBufferingUpdateListener{

private Button btn_play;
private SeekBar seekBar;
private MediaPlayer mediaPlayer;
private int lengthOfAudio;
private int length=0;
String URL = (new AppConfig()).getURL();
private final String url = URL + "/play/song.mp3";
private final Handler handler = new Handler();
private final Runnable r = new Runnable() { 
    public void run() {
        updateSeekProgress();                   
    }
};

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

@SuppressLint("NewApi")
@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.player_fragment, container, false);
    btn_play = (Button) view.findViewById(R.id.btn_play);
    btn_play.setOnClickListener(new OnClickListener());
    seekBar = (SeekBar)getActivity().findViewById(R.id.seekBar);
    seekBar.setOnTouchListener(this);

    mediaPlayer = new MediaPlayer();
    mediaPlayer.setOnBufferingUpdateListener(this);
    mediaPlayer.setOnCompletionListener(this);

    return view;
}}

片段XML

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<SeekBar
android:id="@+id/seekBar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="3dp" />
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:gravity="center_horizontal"
android:orientation="horizontal" >
<Button
    android:id="@+id/btn_play"
    android:layout_width="70dp"
    android:layout_height="wrap_content"
    android:text="play" />
</LinearLayout>
</LinearLayout>

Answer 1

另一个问题：

seekBar = (SeekBar)getActivity().findViewById(R.id.seekBar);
seekBar.setOnTouchListener(this);

seekBar仅定义为Fragment布局的一部分，而不是Activity的。对getActivity().findViewById()的调用应返回null，并在尝试添加监听器时生成NPE。但是，需要更多信息（来自堆栈跟踪）以查看是否有其他错误（除此之外和字符串比较）。

什么是有效的：

seekBar = (SeekBar)view.findViewById(R.id.seekBar);
seekBar.setOnTouchListener(this);

Answer 2

首先，您为fill_parent的宽度和高度提供了ListView，这使得您的ListView占据整个父级（此处为LinearLayout），因此Fragment没有位置}。您null检查代码if (frag == null)是件好事，但是您又试图将您的片段添加到屏幕上没有的View（未附加）。

如果您发现自己的Fragment未附加到视图层次结构中，则可能需要启动新活动。

if (frag == null) {
    Intent playerActivity = new Intent(DisplaysongDetails.this, PlayerActivity.class)
    startActivity(playerActivity);
    }

现在，创建一个名为Activity的新PlayerActivity，并在其布局中添加PlayerFragment。您可以使用Extras传递任何商品数据。

碎片未显示

2 个答案: