Android的CursorLoader和LoaderManager错误 [英] Android CursorLoader and LoaderManager Error
问题描述
我想实现对10的分钟API
一个CursorLoader和LoaderManager不过，我不断收到关于AsyncTaskLoader.class的63号线（在异常发生的AsyncTaskLoader.class的源$ C $ C的IllegalArgument异常如下，并在此<一个href=\"http://grep$c$c.com/file/repo1.maven.org/maven2/com.google.android/support-v4/r7/android/support/v4/content/AsyncTaskLoader.java#AsyncTaskLoader.LoadTask.onPostExecute%28java.lang.Object%29\"相对=nofollow> 链接 。
/ *运行在UI线程* /
@覆盖
保护无效onPostExecute（D数据）{
如果（调试）Log.v（TAG，这+onPostExecute）;
尝试{
AsyncTaskLoader.this.dispatchOnLoadComplete（此，数据）;
} {最后
done.countDown（）;
}
}
下面是在错误的堆栈：
AsyncTaskLoader $ LoadTask.onPostExecute（对象）行：63
AsyncTaskLoader $ LoadTask（ModernAsyncTask）.finish（对象）线：461
ModernAsyncTask.access $ 500（ModernAsyncTask，对象）行：47
ModernAsyncTask $ InternalHandler.handleMessage（消息）线：474
ModernAsyncTask $ InternalHandler（处理器）.dispatchMessage（消息）行：99
Looper.loop（）行：137
ActivityThread.main（字符串[]）行：4424
Method.invokeNative（对象，对象[]，上课，下课[]，类，整型，布尔）行：不可用[本机方法]
Method.invoke（对象，对象...）线：511
ZygoteInit $ MethodAndArgsCaller.run（）行：784
ZygoteInit.main（字符串[]）线：551
NativeStart.main（字符串[]）行：不可用[本机方法]
我测试了我的内容提供商，我验证了查询方法返回从我SQLite数据库的有效光标。下面是我的活动源$ C $ C，我想实现的CursorLoader和LoaderManager：
进口android.database.Cursor;
进口android.os.Bundle;
进口android.support.v4.app.FragmentActivity;
进口android.support.v4.app.LoaderManager;
进口android.support.v4.content.CursorLoader;
进口android.support.v4.content.Loader;
进口android.support.v4.widget.SimpleCursorAdapter;
进口android.widget.ListView;公共类Screen1_MainData扩展FragmentActivity实现LoaderManager.LoaderCallbacks＆LT;＆光标GT; { SimpleCursorAdapter适配器;
LV的ListView; @覆盖
保护无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.screen1_maindata）;
initLoader（）;
} 无效initLoader（）{
的String [] = uiBindFrom {Useful_Info_TableMetaData.USEFUL_INFO_COLUMN_NAME};
INT [] = uiBindTo {R.id.name};
LV =（ListView控件）findViewById（R.id.screen1_MainListView）;
getSupportLoaderManager（）initLoader（0，null，则此）。 适配器=新SimpleCursorAdapter（这一点，R.layout.row，空，uiBindFrom，
uiBindTo，0）;
lv.setAdapter（适配器）;
}@覆盖
公共装载机＆LT;＆光标GT; onCreateLoader（INT为arg0，ARG1捆绑）{ 的String [] =投影{Useful_Info_TableMetaData.USEFUL_INFO_COLUMN_NAME}; 返回新CursorLoader（
对此，//活动场景
Useful_Info_TableMetaData.CONTENT_URI，投影，NULL，NULL，
空值）;
} @覆盖
公共无效onLoadFinished（装载机＆LT;＆光标GT;装载机，游标数据）{
adapter.swapCursor（数据）;
} @覆盖
公共无效onLoaderReset（装载机＆LT;＆光标GT;装载机）{
adapter.swapCursor（NULL）;
}
}
有谁看到这里的东西，我做错了？
感谢。
该应用程序似乎使它到
@覆盖
公共无效onLoadFinished（装载机＆LT;＆光标GT;装载机，游标数据）{
adapter.swapCursor（数据）;
}
，然后抛出异常那里。
下面是logcat的：
08-03 23：33：20.736：E / AndroidRuntime（17256）：致命异常：主要
08-03 23：33：20.736：E / AndroidRuntime（17256）：java.lang.IllegalArgumentException异常：列'_id'不存在
08-03 23：33：20.736：E / AndroidRuntime（17256）：在android.database.AbstractCursor.getColumnIndexOrThrow（AbstractCursor.java:267）
08-03 23：33：20.736：E / AndroidRuntime（17256）：在android.database.CursorWrapper.getColumnIndexOrThrow（CursorWrapper.java:78）
08-03 23：33：20.736：E / AndroidRuntime（17256）：在android.support.v4.widget.CursorAdapter.swapCursor（CursorAdapter.java:344）
08-03 23：33：20.736：E / AndroidRuntime（17256）：在android.support.v4.widget.SimpleCursorAdapter.swapCursor（SimpleCursorAdapter.java:326）
尝试移动 initLoader 您的来电后， lv.setAdapter 。这将确保 onLoadFinished （因而 adapter.swapCursor（数据））将被调用的之后的 SimpleCursorAdapter 已与相关联的ListView 。
此外，请确保您的数据库中有一个名为列 _id 为您的主键，为的CursorAdapter 荣获' ŧ否则工作。 _id 需要返回从 CursorLoader 的结果的一部分。否则会抛出异常。
I am trying to implement a CursorLoader and LoaderManager on a min API of 10.
However, I keep getting an IllegalArgument Exception on Line 63 of AsyncTaskLoader.class (The source Code of the AsyncTaskLoader.class where the exception is happening is Below and at this link.
/* Runs on the UI thread */
@Override
protected void onPostExecute(D data) {
if (DEBUG) Log.v(TAG, this + " onPostExecute");
try {
AsyncTaskLoader.this.dispatchOnLoadComplete(this, data);
} finally {
done.countDown();
}
}
Below is the stack upon the error:
AsyncTaskLoader$LoadTask.onPostExecute(Object) line: 63
AsyncTaskLoader$LoadTask(ModernAsyncTask).finish(Object) line: 461
ModernAsyncTask.access$500(ModernAsyncTask, Object) line: 47
ModernAsyncTask$InternalHandler.handleMessage(Message) line: 474
ModernAsyncTask$InternalHandler(Handler).dispatchMessage(Message) line: 99
Looper.loop() line: 137
ActivityThread.main(String[]) line: 4424
Method.invokeNative(Object, Object[], Class, Class[], Class, int, boolean) line: not available [native method]
Method.invoke(Object, Object...) line: 511
ZygoteInit$MethodAndArgsCaller.run() line: 784
ZygoteInit.main(String[]) line: 551
NativeStart.main(String[]) line: not available [native method]
I tested my content provider and I validated that the query method returns a valid cursor from my Sqlite Database. Below is the source code of my activity that I am trying to implement the CursorLoader and LoaderManager:
import android.database.Cursor;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
import android.support.v4.widget.SimpleCursorAdapter;
import android.widget.ListView;
public class Screen1_MainData extends FragmentActivity implements LoaderManager.LoaderCallbacks<Cursor> {
SimpleCursorAdapter adapter;
ListView lv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.screen1_maindata);
initLoader();
}
void initLoader() {
String[] uiBindFrom = { Useful_Info_TableMetaData.USEFUL_INFO_COLUMN_NAME };
int[] uiBindTo = { R.id.name };
lv = (ListView) findViewById(R.id.screen1_MainListView);
getSupportLoaderManager().initLoader(0, null, this);
adapter = new SimpleCursorAdapter(this, R.layout.row, null, uiBindFrom,
uiBindTo, 0);
lv.setAdapter(adapter);
}
@Override
public Loader<Cursor> onCreateLoader(int arg0, Bundle arg1) {
String[] projection = { Useful_Info_TableMetaData.USEFUL_INFO_COLUMN_NAME };
return new CursorLoader(
this, // The Activity context
Useful_Info_TableMetaData.CONTENT_URI, projection, null, null,
null);
}
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
adapter.swapCursor(data);
}
@Override
public void onLoaderReset(Loader<Cursor> loader) {
adapter.swapCursor(null);
}
}
Does anyone see something here that I am doing wrong?
Thanks.
The app seems to make it to
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
adapter.swapCursor(data);
}
and then it throws the exception there.
Below is the logcat:
08-03 23:33:20.736: E/AndroidRuntime(17256): FATAL EXCEPTION: main
08-03 23:33:20.736: E/AndroidRuntime(17256): java.lang.IllegalArgumentException: column '_id' does not exist
08-03 23:33:20.736: E/AndroidRuntime(17256): at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:267)
08-03 23:33:20.736: E/AndroidRuntime(17256): at android.database.CursorWrapper.getColumnIndexOrThrow(CursorWrapper.java:78)
08-03 23:33:20.736: E/AndroidRuntime(17256): at android.support.v4.widget.CursorAdapter.swapCursor(CursorAdapter.java:344)
08-03 23:33:20.736: E/AndroidRuntime(17256): at android.support.v4.widget.SimpleCursorAdapter.swapCursor(SimpleCursorAdapter.java:326)
Try moving initLoader after your call to lv.setAdapter. This will ensure that onLoadFinished (and thus adapter.swapCursor(data)) will be called after the SimpleCursorAdapter has been associated with the ListView .
Also, make sure your database has a column named _id for your primary key, as the CursorAdapter won't work otherwise. _id needs to be returned as a part of the results from the CursorLoader's. Otherwise an exception will be thrown.
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