loadermanager 中的 asynctask 致命异常 #1答案

【问题标题】：asynctask fatal exception #1 in loadermanagerloadermanager 中的 asynctask 致命异常 #1
【发布时间】：2014-06-27 14:33:54
【问题描述】：

我的 loadermanager 有问题，它应该从我的 contentprovider 中提取我的数据。错误是：

06-27 10:14:29.053: E/AndroidRuntime(2270): FATAL EXCEPTION: AsyncTask #1
06-27 10:14:29.053: E/AndroidRuntime(2270): Process: com.trackme, PID: 2270
06-27 10:14:29.053: E/AndroidRuntime(2270): java.lang.RuntimeException: An error occured while executing doInBackground()
06-27 10:14:29.053: E/AndroidRuntime(2270):     at android.os.AsyncTask$3.done(AsyncTask.java:300)
06-27 10:14:29.053: E/AndroidRuntime(2270):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
06-27 10:14:29.053: E/AndroidRuntime(2270):     at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
06-27 10:14:29.053: E/AndroidRuntime(2270):     at java.util.concurrent.FutureTask.run(FutureTask.java:242)
06-27 10:14:29.053: E/AndroidRuntime(2270):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
06-27 10:14:29.053: E/AndroidRuntime(2270):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
06-27 10:14:29.053: E/AndroidRuntime(2270):     at java.lang.Thread.run(Thread.java:841)
06-27 10:14:29.053: E/AndroidRuntime(2270): Caused by: java.lang.IndexOutOfBoundsException`

我的代码是：

public class RoutesListActivity extends ListActivity implements LoaderManager.LoaderCallbacks<Cursor>{

public static final String TAG = "RouteList";

private static final int LOADER_ID = 1;

public static final int ACTIVITY_CREATE = 0;
public static final int ACTIVITY_RESULTS = 1;

private SimpleCursorAdapter mRoutesCursorAdapter;

@Override
protected void onCreate(Bundle savedInstanceState){

    Log.i(TAG, "onCreate della lista ");

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_routes_list);

    String[] from = new String[] {GeoProvider.KEY_ROWID};
    int[] to = new int[] {R.id.route1};

    mRoutesCursorAdapter = new SimpleCursorAdapter(this, R.layout.route_row, null, from, to, 0);
    setListAdapter(mRoutesCursorAdapter);

    //permette di interfacciare l'activity col loader
    LoaderManager lm = getLoaderManager();
    lm.initLoader(LOADER_ID, null, this);

    registerForContextMenu(getListView());

    Log.i(TAG, "Fine del metodo onCreate");
}


public boolean onCreateOptionMenu(Menu menu) {

    Log.i(TAG, "Creazione dell'OptionMenu");

    super.onCreateOptionsMenu(menu);
    getMenuInflater().inflate(R.menu.routes_list, menu);
    return true;
}


public boolean onOptionItemSelected(MenuItem item) {

    Log.i(TAG, "Selezione dell'item del menu ");

    super.onOptionsItemSelected(item);
    switch(item.getItemId()) {
    case R.id.create_route:
        createRoute();
        return true;
    }
    return super.onOptionsItemSelected(item);
}

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {

    Log.i(TAG, "selezione elemento della lista ");

    super.onListItemClick(l, v, position, id);
    showResults(id);
}

@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo){
    super.onCreateContextMenu(menu, v, menuInfo);
    getMenuInflater().inflate(R.menu.context, menu);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
    super.onActivityResult(requestCode, resultCode, intent);
}

private void createRoute(){
    Log.i(TAG , "createRoute");
    Intent toRoute = new Intent(this, GeoActivity.class);
    startActivityForResult(toRoute, ACTIVITY_CREATE);
}

private void deleteRoute(long id) {
    Log.i(TAG , "deleteRoute");
    Uri baseUri = GeoProvider.GEO_TABLE_URI;
    Long idWrapper = Long.valueOf(id);
    getContentResolver().delete(Uri.withAppendedPath(baseUri, idWrapper.toString()), null, null);
}

private void showResults(long id){
    Log.i(TAG , "showResults");
    Intent toResults = new Intent(this, Results.class);
    toResults.putExtra(GeoProvider.KEY_ROWID, id);
    startActivityForResult(toResults, ACTIVITY_RESULTS);
}

//il loader serve per il caricamento asincrono dei dati dal db
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args){
    Log.i(TAG , "onCreateLoader");
    return new CursorLoader(this, GeoProvider.GEO_TABLE_URI, new String[] {GeoProvider.KEY_ROWID},
            null, null, null);
}

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
    Log.i(TAG , "onLoadFinished");
    switch(loader.getId()){
    case LOADER_ID:
        Log.i(TAG , "onLoadFinished case LOADER_ID");
        mRoutesCursorAdapter.swapCursor(cursor);
        break;
    }
    Log.i(TAG , "fine onLoadFinished");
}

@Override
public void onLoaderReset(Loader<Cursor> arg0){
    mRoutesCursorAdapter.swapCursor(null);
}

}

我不明白为什么不使用类 AsyncTask 会出现此错误！我的 contentProvider 应该没问题，在我看来错误就在这里，但我不知道在哪里......

感谢您的帮助

【问题讨论】：

标签： java android android-asynctask

【解决方案1】：

您在 AsyncTask 中获得了 IndexOutOfBoundsException。这意味着您正在尝试访问超出数组范围的索引。代码示例：

int[] x = new int[5]; // x has size 5
int y = x[10]; // OutOfBounds since x has size of 5, and trying to access 11th element (index 10)

您的示例仅显示您的活动，因此我找不到您必须更改 AsyncTask 的内容和位置，但您可以查看 this 一些相关问题以查看 IndexOutOfBoundsException 的另一个示例。

【讨论】：

【解决方案2】：

由于我无法发表评论，所以我会写下我的建议作为答案。您覆盖的其中一种方法可能使用 asynctask 来执行后台工作。当您尝试更改 UI 元素或应在 UIThread 上运行的任何内容时，会发生此异常。尝试检查您正在执行 UIThread 工作的函数，并从开发者网站查看该函数的工作原理。

【讨论】：