Android 分区列表视图不显示任何内容

我的代码中没有错误，但是当我运行应用程序时，屏幕只是空白

有人知道为什么会这样吗？
我的目标是，一旦我有了这个工作，我想添加一个来自json提要的数据到其中

以下是我的活动：

import android.app.ListActivity;
import android.content.Context;
import android.database.CharArrayBuffer;
import android.database.Cursor;
import android.os.Bundle;
import android.provider.MediaStore.Audio.Media;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CursorAdapter;
import android.widget.ListView;
import android.widget.TextView;
import co.uk.listapp.myapp.util.NotifyingAsyncQueryHandler;
import co.uk.listapp.myapp.util.NotifyingAsyncQueryHandler.NotifyingAsyncQueryListener;

/**
 * Shows a smart way of handling separators in {@link ListView}s. It also shows
 * some ways to boost your {@link ListView}s using techniques like 'section
 * caching', ViewHolder, CharArrayBuffer, etc.
 * 

 */
public class ChooseTeamActivity extends ListActivity implements NotifyingAsyncQueryListener {

    private AudioFilesAdapter mAdapter;
    private NotifyingAsyncQueryHandler mQueryHandler;

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

        mAdapter = new AudioFilesAdapter(this, null);
        setListAdapter(mAdapter);

        // Starts querying the media provider. This is done asynchronously not
        // to possibly block the UI or even worse fire an ANR...
        mQueryHandler = new NotifyingAsyncQueryHandler(getContentResolver(), this);
        mQueryHandler.startQuery(Media.EXTERNAL_CONTENT_URI, AudioFilesQuery.PROJECTION, AudioFilesQuery.SORT_ORDER);
    }

    @Override
    protected void onDestroy() {
        // Clear any strong reference to this Activity
        mQueryHandler.clearQueryListener();
        super.onDestroy();
    }

    public void onQueryComplete(int token, Object cookie, Cursor cursor) {
        if (cursor != null) {
            startManagingCursor(cursor);
        }
        mAdapter.changeCursor(cursor);
    }

    private static class AudioFilesViewHolder {
        public TextView separator;
        public TextView titleView;
        public CharArrayBuffer titleBuffer = new CharArrayBuffer(128);
    }

    private static class AudioFilesAdapter extends CursorAdapter {

        /**
         * State of ListView item that has never been determined.
         */
        private static final int STATE_UNKNOWN = 0;

        /**
         * State of a ListView item that is sectioned. A sectioned item must
         * display the separator.
         */
        private static final int STATE_SECTIONED_CELL = 1;

        /**
         * State of a ListView item that is not sectioned and therefore does not
         * display the separator.
         */
        private static final int STATE_REGULAR_CELL = 2;

        private final CharArrayBuffer mBuffer = new CharArrayBuffer(128);
        private int[] mCellStates;

        public AudioFilesAdapter(Context context, Cursor cursor) {
            super(context, cursor);
            mCellStates = cursor == null ? null : new int[cursor.getCount()];
        }

        @Override
        public void changeCursor(Cursor cursor) {
            super.changeCursor(cursor);
            mCellStates = cursor == null ? null : new int[cursor.getCount()];
        }

        @Override
        public void bindView(View view, Context context, Cursor cursor) {

            final AudioFilesViewHolder holder = (AudioFilesViewHolder) view.getTag();

            /*
             * Separator
             */
            boolean needSeparator = false;

            final int position = cursor.getPosition();
            cursor.copyStringToBuffer(AudioFilesQuery.TITLE, holder.titleBuffer);

            switch (mCellStates[position]) {
                case STATE_SECTIONED_CELL:
                    needSeparator = true;
                    break;

                case STATE_REGULAR_CELL:
                    needSeparator = false;
                    break;

                case STATE_UNKNOWN:
                default:
                    // A separator is needed if it's the first itemview of the
                    // ListView or if the group of the current cell is different
                    // from the previous itemview.
                    if (position == 0) {
                        needSeparator = true;
                    } else {
                        cursor.moveToPosition(position - 1);

                        cursor.copyStringToBuffer(AudioFilesQuery.TITLE, mBuffer);
                        if (mBuffer.sizeCopied > 0 && holder.titleBuffer.sizeCopied > 0 && mBuffer.data[0] != holder.titleBuffer.data[0]) {
                            needSeparator = true;
                        }

                        cursor.moveToPosition(position);
                    }

                    // Cache the result
                    mCellStates[position] = needSeparator ? STATE_SECTIONED_CELL : STATE_REGULAR_CELL;
                    break;
            }

            if (needSeparator) {
                holder.separator.setText(holder.titleBuffer.data, 0, 1);
                holder.separator.setVisibility(View.VISIBLE);
            } else {
                holder.separator.setVisibility(View.GONE);
            }

            /*
             * Title
             */
            holder.titleView.setText(holder.titleBuffer.data, 0, holder.titleBuffer.sizeCopied);



        }

        @Override
        public View newView(Context context, Cursor cursor, ViewGroup parent) {

            View v = LayoutInflater.from(context).inflate(R.layout.single_item, parent, false);

            // The following code allows us to keep a reference on the child
            // views of the item. It prevents us from calling findViewById at
            // each getView/bindView and boosts the rendering code.
            AudioFilesViewHolder holder = new AudioFilesViewHolder();
            holder.separator = (TextView) v.findViewById(R.id.separator);
            holder.titleView = (TextView) v.findViewById(R.id.title);


            v.setTag(holder);

            return v;
        }

    }


     // Keep query data in one place


    private interface AudioFilesQuery {
        String[] PROJECTION = {
                Media._ID, Media.TITLE, Media.ALBUM, Media.ARTIST
        };

        int TITLE = 1;
        //int ALBUM = 2;
        //int ARTIST = 3;

        String SORT_ORDER = Media.TITLE + " ASC";
    }

}

NotfyingAsyncQueryHandler

import java.lang.ref.WeakReference;

import android.content.AsyncQueryHandler;
import android.content.ContentResolver;
import android.database.Cursor;
import android.net.Uri;

/**
 * A particular {@link AsyncQueryHandler} allowing clients to be notified via a
 * listener. The {@link NotifyingAsyncQueryHandler} also make sure no strong
 * reference is kept on the given listener (as it is often a Context).
 * 

 */
public class NotifyingAsyncQueryHandler extends AsyncQueryHandler {

    private WeakReference<NotifyingAsyncQueryListener> mListener;

    /**
     * Client may use this to listen to completed query operations.

     */
    public interface NotifyingAsyncQueryListener {
        void onQueryComplete(int token, Object cookie, Cursor cursor);
    }

    public NotifyingAsyncQueryHandler(ContentResolver resolver, NotifyingAsyncQueryListener listener) {
        super(resolver);
        setQueryListener(listener);
    }

    /**
     * Assign the given {@link NotifyingAsyncQueryListener}.
     */
    public void setQueryListener(NotifyingAsyncQueryListener listener) {
        mListener = (listener != null) ? new WeakReference<NotifyingAsyncQueryListener>(listener) : null;
    }

    public void clearQueryListener() {
        mListener = null;
    }

    public void startQuery(Uri uri, String[] projection) {
        startQuery(-1, null, uri, projection, null, null, null);
    }

    public void startQuery(Uri uri, String[] projection, String sortOrder) {
        startQuery(-1, null, uri, projection, null, null, sortOrder);
    }

    @Override
    protected void onQueryComplete(int token, Object cookie, Cursor cursor) {
        final NotifyingAsyncQueryListener listener = (mListener == null) ? null : mListener.get();
        if (listener != null) {
            listener.onQueryComplete(token, cookie, cursor);
        } else if (cursor != null) {
            cursor.close();
        }
    }
}

import java.lang.ref.WeakReference；
导入android.content.AsyncQueryHandler；
导入android.content.ContentResolver；
导入android.database.Cursor；
导入android.net.Uri；
/**
*一种特殊的{@link AsyncQueryHandler}，允许通过
*听众。{@link NotifyingAsyncQueryHandler}还确保没有强
*引用保留在给定的侦听器上（因为它通常是上下文）。
* 
*/
公共类NotifyingAsyncQueryHandler扩展了AsyncQueryHandler{
私营部门；
/**
*客户端可以使用它来侦听已完成的查询操作。
*/
公共接口通知SyncQueryListener{
void onQueryComplete（int标记、对象cookie、光标）；
}
公共NotifyingAsyncQueryHandler（ContentResolver解析器，NotifyingAsyncQueryListener侦听器）{
超级（解析器）；
setQueryListener（监听器）；
}
/**
*分配给定的{@link NotifyingAsyncQueryListener}。
*/
public void setQueryListener（通知SyncQueryListener侦听器）{
mListener=（侦听器！=null）？新的WeakReference（侦听器）：null；
}
公共无效clearQueryListener（）{
mListener=null；
}
public void startQuery（Uri，字符串[]投影）{
startQuery（-1，null，uri，projection，null，null，null）；
}
public void startQuery（Uri、字符串[]投影、字符串排序器）{
startQuery（-1，null，uri，projection，null，null，sortOrder）；
}
@凌驾
受保护的void onQueryComplete（int标记、对象cookie、光标）{
final NotifyingAsyncQueryListener=（mListener==null）？null:mListener.get（）；
if（侦听器！=null）{
onQueryComplete（令牌、cookie、游标）；
}else if（光标！=null）{
cursor.close（）；
}
}
}

single_item.xml

<?xml version="1.0" encoding="utf-8"?>



<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:paddingBottom="8dp"
    android:background="@android:color/white">

    <TextView
        style="?android:attr/listSeparatorTextViewStyle"
        android:id="@+id/separator"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textColor="@android:color/white" />

    <TextView
        android:id="@+id/title"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:singleLine="true"
        android:textColor="@color/blue"
        android:textSize="16sp"
        android:textStyle="bold"
        android:paddingTop="8dp"
        android:paddingRight="8dp"
        android:paddingLeft="8dp" />



</LinearLayout>

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请参考此github网站。你可以得到你想要的。