Android ExpandableListView sqlite错误

我有一个包含事件名称和日期的数据库。我正在尝试使用游标创建一个expandablelistview，该游标将按事件日期对事件进行分组

我没有找到很多与我的情况相关的信息。SDK中的例子是使用内容提供者，我还没有读过/尝试过，我已经用旧的方法设置了数据库助手

我发现我认为是一个很好的例子，并试图将它适应我的使用，但它崩溃了，我无法找出我做错了什么

我的代码

import android.app.ExpandableListActivity;
import android.content.Context;
import android.database.Cursor;
import android.os.Bundle;
import android.widget.SimpleCursorTreeAdapter;

public class ExpandableListTestActivity extends ExpandableListActivity {

    private AttendanceDB mDbHelper;  
    private Cursor mGroupsCursor; 
    private int mGroupIdColumnIndex; 
    private MyExpandableListAdapter mAdapter; 

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

                    mDbHelper = new AttendanceDB(this); 
                    mDbHelper.open(); 
                    fillData(); 
    } 

    private void fillData() { 
                    mGroupsCursor = mDbHelper.fetchGroup();   
                    startManagingCursor(mGroupsCursor); 

                    mAdapter = new MyExpandableListAdapter(mGroupsCursor,this, 
                                                    android.R.layout.simple_expandable_list_item_1, 
                                                    android.R.layout.simple_expandable_list_item_1, 
                                                    new String[] { AttendanceDB.EVENT_DATE }, 
                                                    new int[] { android.R.id.text1 }, 
                                                    new String[] { AttendanceDB.EVENT_NAME }, 
                                                    new int[] { android.R.id.text1 }); 
                    setListAdapter(mAdapter); 
    } 

    public class MyExpandableListAdapter extends SimpleCursorTreeAdapter { 

                    public MyExpandableListAdapter(Cursor cursor, Context context, 
                                                    int groupLayout, int childLayout, String[] groupFrom, 
                                                    int[] groupTo, String[] childrenFrom, int[] childrenTo) { 
                                    super(context, cursor, groupLayout, groupFrom, groupTo, 
                                                                    childLayout, childrenFrom, childrenTo); 
                    } 

                    @Override 
                    protected Cursor getChildrenCursor(Cursor groupCursor) { 
                                    Cursor childCursor = mDbHelper 
                                                                    .fetchChildren(groupCursor.getString(groupCursor.getColumnIndex(AttendanceDB.EVENT_DATE))); 
                                    startManagingCursor(childCursor); 
                                    return childCursor; 
                    } 
    } 
}

当我运行此代码时，我得到以下信息：

E/AndroidRuntime(30329): FATAL    EXCEPTION: main
E/AndroidRuntime(30329): java.lang.RuntimeException: Unable to start activity ComponentInfo{cdc.workshopapps.explist/cdc.workshopapps.explist.ExpandableListTestActivity}: java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it
E/AndroidRuntime(30329):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815)
E/AndroidRuntime(30329):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831)
E/AndroidRuntime(30329):    at android.app.ActivityThread.access$500(ActivityThread.java:122)
E/AndroidRuntime(30329):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1024)
E/AndroidRuntime(30329):    at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(30329):    at android.os.Looper.loop(Looper.java:132)
E/AndroidRuntime(30329):    at android.app.ActivityThread.main(ActivityThread.java:4123)
E/AndroidRuntime(30329):    at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(30329):    at java.lang.reflect.Method.invoke(Method.java:491)
E/AndroidRuntime(30329):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
E/AndroidRuntime(30329):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
E/AndroidRuntime(30329):    at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(30329): Caused by: java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it
E/AndroidRuntime(30329):    at android.database.CursorWindow.getLong_native(Native Method)
E/AndroidRuntime(30329):    at android.database.CursorWindow.getLong(CursorWindow.java:436)
E/AndroidRuntime(30329):    at android.database.AbstractWindowedCursor.getLong(AbstractWindowedCursor.java:56)
E/AndroidRuntime(30329):    at android.widget.CursorTreeAdapter$MyCursorHelper.getId(CursorTreeAdapter.java:437)
E/AndroidRuntime(30329):    at android.widget.CursorTreeAdapter.getGroupId(CursorTreeAdapter.java:192)
E/AndroidRuntime(30329):    at android.widget.ExpandableListConnector.getItemId(ExpandableListConnector.java:421)
E/AndroidRuntime(30329):    at android.widget.AdapterView.getItemIdAtPosition(AdapterView.java:744)
E/AndroidRuntime(30329):    at android.widget.AdapterView.setSelectedPositionInt(AdapterView.java:1087)
E/AndroidRuntime(30329):    at android.widget.ListView.setAdapter(ListView.java:458)
E/AndroidRuntime(30329):    at android.widget.ExpandableListView.setAdapter(ExpandableListView.java:469)
E/AndroidRuntime(30329):    at android.app.ExpandableListActivity.setListAdapter(ExpandableListActivity.java:246)
E/AndroidRuntime(30329):    at cdc.workshopapps.explist.ExpandableListTestActivity.fillData(ExpandableListTestActivity.java:36)
E/AndroidRuntime(30329):    at cdc.workshopapps.explist.ExpandableListTestActivity.onCreate(ExpandableListTestActivity.java:22)
E/AndroidRuntime(30329):    at android.app.Activity.performCreate(Activity.java:4397)
E/AndroidRuntime(30329):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
E/AndroidRuntime(30329):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779)
E/AndroidRuntime(30329):    ... 11 more

我认为这意味着我在游标中返回的列有问题。但是如果我将filldata（）方法更改为以下内容（只是为了检查我的游标/列）：

祝酒会输出预期的事件日期和事件名称数据，因此我不知道哪里出错了

其他（可能）相关代码：

public Cursor fetchGroup() {
    String query ="SELECT DISTINCT date FROM events"; 
      return mDb.rawQuery(query,null); 
}

public Cursor fetchChildren(String date) {
    Cursor c = mDb.query(EVENT_TABLE, new String[] { EVENT_ROWID,
            EVENT_NAME }, EVENT_DATE + "='" + date + "'" ,
            null, null, null, null);

return c;
}

---

任何帮助都将不胜感激。

在从游标获取数据之前，您必须调用Cursor.moveToFirst（）；否则它不会初始化。您在getChildrenCursor（）函数中遗漏了这一点

加：

---

CursorTreeAdapter在光标中需要一个“_id”字段。如果数据库中有此字段，只需将其添加到fetchGroup和fetchChildren查询中即可

否则，添加“rowid as_id”。这使用SQLite内部行编号

---

不幸的是，这不是问题所在（尽管我添加了一个moveToFirst（），以防万一，但还是出现了相同的错误）。问题似乎是我的光标上缺少了一列，但我肯定也不知道在哪里/如何找到。我会在一堆圣经上发誓，我读了三遍那个链接，却错过了关于需要id的那一点。它正在工作。现在我只需要让它在一个片段中工作p但如果我遇到问题，这可能是另一天的问题。谢谢你的帮助！

public Cursor fetchGroup() {
    String query ="SELECT DISTINCT date FROM events"; 
      return mDb.rawQuery(query,null); 
}

public Cursor fetchChildren(String date) {
    Cursor c = mDb.query(EVENT_TABLE, new String[] { EVENT_ROWID,
            EVENT_NAME }, EVENT_DATE + "='" + date + "'" ,
            null, null, null, null);

return c;
}

groupCursor.moveToFirst();