使用cursorloader时，应用程序在启动时崩溃

时间：2017-03-30 00:44:05

标签： android android-cursorloader

首次登陆时应用程序崩溃并在使用CursorLoaders回调方法时给出了这些错误（在此之前我在主UI中加载数据库表并且在这种情况下没有任何事情发生但是当更改为CursorLoader以加载和更改时在背景中的UI出现这个问题），我不知道使应用程序崩溃的代码行，但我认为导入有关它，请帮忙吗？

   03-30 02:10:06.441    1564-1591/android.process.acore E/DatabaseUtils﹕   Writing exception to parcel
   java.lang.IllegalArgumentException: Invalid column name
        at    android.database.sqlite.SQLiteQueryBuilder.computeProjection(SQLiteQueryBuilder.java:632)
        at android.database.sqlite.SQLiteQueryBuilder.buildQuery(SQLiteQueryBuilder.java:447)
        at android.database.sqlite.SQLiteQueryBuilder.query(SQLiteQueryBuilder.java:393)
        at com.android.providers.contacts.ContactsProvider2.query(ContactsProvider2.java:6493)
        at com.android.providers.contacts.ContactsProvider2.queryLocal(ContactsProvider2.java:6443)
        at com.android.providers.contacts.ContactsProvider2.query(ContactsProvider2.java:5038)
        at android.content.ContentProvider$Transport.query(ContentProvider.java:211)
        at android.content.ContentProviderNative.onTransact(ContentProviderNative.java:112)
        at android.os.Binder.execTransact(Binder.java:446)
03-30 02:10:06.446  24098-24122/com.example.android.pets E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1
Process: com.example.android.pets, PID: 24098
java.lang.RuntimeException: An error occured while executing doInBackground()
        at android.os.AsyncTask$3.done(AsyncTask.java:304)
        at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
        at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
        at java.util.concurrent.FutureTask.run(FutureTask.java:242)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
        at java.lang.Thread.run(Thread.java:818)
 Caused by: java.lang.IllegalArgumentException: Invalid column name
        at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:167)
        at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:137)
        at android.content.ContentProviderProxy.query(ContentProviderNative.java:421)
        at android.content.ContentResolver.query(ContentResolver.java:478)
        at android.content.CursorLoader.loadInBackground(CursorLoader.java:64)
        at android.content.CursorLoader.loadInBackground(CursorLoader.java:42)
        at android.content.AsyncTaskLoader.onLoadInBackground(AsyncTaskLoader.java:312)
        at android.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:69)
        at android.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:57)
        at android.os.AsyncTask$2.call(AsyncTask.java:292)
        at java.util.concurrent.FutureTask.run(FutureTask.java:237)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
        at java.lang.Thread.run(Thread.java:818)

这是指向https://github.com/NayirMicheal/petsapp上应用程序的整个链接的链接，此应用程序创建宠物数据库并将这些宠物保存到数据库中，然后从数据库中重新获取它们并使用listview通过CursorLoader显示检索到UI的数据和CursorAdapter 这是mainActivity的代码

package com.example.android.pets;

import android.content.ContentValues;
import android.app.LoaderManager;
import android.content.CursorLoader;
import android.content.Loader;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ListView;
import android.widget.Toast;

import com.example.android.pets.data.PetContract;
import com.example.android.pets.data.PetDbHelper;


public class CatalogActivity extends AppCompatActivity implements     LoaderManager.LoaderCallbacks<Cursor> {
private static final int URI_LOADER = 0;
private PetDbHelper mDbHelper;
SQLiteDatabase db;
ListView lvItems;
PetCursorAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_catalog);
 lvItems = (ListView) findViewById(R.id.lstview);
View emptyView = findViewById(R.id.empty_view);
lvItems.setEmptyView(emptyView);

adapter = new PetCursorAdapter(this, null);
lvItems.setAdapter(adapter);

// Setup FAB to open EditorActivity
FloatingActionButton fab = (FloatingActionButton)  findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        Intent intent = new Intent(CatalogActivity.this,      EditorActivity.class);
        startActivity(intent);
    }
  });
mDbHelper = new PetDbHelper(this);
db=mDbHelper.getWritableDatabase();
getLoaderManager().initLoader(URI_LOADER, null, this);

 }

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
 // Inflate the menu options from the res/menu/menu_catalog.xml file.
 // This adds menu items to the app bar.
 getMenuInflater().inflate(R.menu.menu_catalog, menu);
 return true;
 }

 @Override
 public boolean onOptionsItemSelected(MenuItem item) {
 // User clicked on a menu option in the app bar overflow menu
 switch (item.getItemId()) {
    // Respond to a click on the "Insert dummy data" menu option
    case R.id.action_insert_dummy_data:
        insertdummy();
        return true;
    // Respond to a click on the "Delete all entries" menu option
    case R.id.action_delete_all_entries:
        // Do nothing for now
        return true;
    }
  return super.onOptionsItemSelected(item);
  }

 private void insertdummy() {
 ContentValues values=new ContentValues();
 values.put(PetContract.PetEntry.COLUMN_PET_NAME, "toto");
 values.put(PetContract.PetEntry.COLUMN_PET_BREED,"terrier");
 values.put(PetContract.PetEntry.COLUMN_PET_GENDER,     PetContract.PetEntry.GENDER_MALE);
 values.put(PetContract.PetEntry.COLUMN_PET_WEIGHT, 7);
 Uri URI_ID=   getContentResolver().insert(PetContract.PetEntry.CONTENT_URI, values);
 if(URI_ID==null)
  Toast.makeText(getApplicationContext(),  R.string.fail_save,Toast.LENGTH_LONG).show();
 else
    Toast.makeText(getApplicationContext(), R.string.success_save,   Toast.LENGTH_LONG).show();

  }

@Override
public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
String[] projection = {PetContract.PetEntry._ID,
        PetContract.PetEntry.COLUMN_PET_NAME,
        PetContract.PetEntry.COLUMN_PET_BREED};
String selection = null;
String selectionArgs[] =null;
return new CursorLoader(getApplicationContext(),     ContactsContract.Data.CONTENT_URI,
        projection, selection, selectionArgs, null);
 }

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
adapter.swapCursor(cursor);
}

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

1 个答案:

答案 0 :(得分：0)

我认为你必须在这里使用 PetContract ：

@Override
public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
    String[] projection = {PetContract.PetEntry._ID,
    PetContract.PetEntry.COLUMN_PET_NAME,PetContract.PetEntry.COLUMN_PET_BREED};
    String selection = null;
    String selectionArgs[] =null;
    return new CursorLoader(this, PetContract.CONTENT_URI,
    projection, selection, selectionArgs, null);
}

我还将 getApplicationContext（）更改为此以获取活动上下文。我不确定，但这就是我在装载机上所做的。尝试一下，看它是否有效，但我认为主要错误将出现在合同部分。

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