每当我使用LoaderManager
方法调用getLoaderManager().initLoader()
时,我会收到错误的第三个参数类型的错误。我传递this
作为第三个参数。任何人都可以告诉我为什么会收到此错误。我在LoaderManager
方法的最后调用了onCreate()
。这是我的代码:
public class CatalogActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Cursor> {
private static final int PET_LOADER = 0;
PetCursorAdapter mCursorAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_catalog);
// 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);
}
});
// Find the ListView which will be populated with the pet data
ListView petListView = (ListView) findViewById(R.id.list);
// Find and set empty view on the ListView, so that it only shows when the list has 0 items.
View emptyView = findViewById(R.id.empty_view);
petListView.setEmptyView(emptyView);
mCursorAdapter = new PetCursorAdapter(this, null);
petListView.setAdapter(mCursorAdapter);
petListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
Intent intent = new Intent(CatalogActivity.this, EditorActivity.class);
Uri currentPetUri = ContentUris.withAppendedId(PetEntry.CONTENT_URI, id);
intent.setData(currentPetUri);
startActivity(intent);
}
});
getLoaderManager().initLoader(PET_LOADER, null, this);
}
private void insertPet() {
ContentValues values = new ContentValues();
values.put(PetEntry.COLUMN_NAME, "Toto");
values.put(PetEntry.COLUMN_BREED, "Terrier");
values.put(PetEntry.COLUMN_GENDER, PetEntry.GENDER_MALE);
values.put(PetEntry.COLUMN_WEIGHT, 7);
Uri newUri = getContentResolver().insert(PetEntry.CONTENT_URI, values);
}
@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:
insertPet();
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);
}
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
String[] projection = {PetEntry._ID,
PetEntry.COLUMN_NAME,
PetEntry.COLUMN_BREED};
return new CursorLoader(this,
PetEntry.CONTENT_URI,
projection,
null,
null,
null);
}
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
mCursorAdapter.swapCursor(data);
}
@Override
public void onLoaderReset(Loader<Cursor> loader) {
mCursorAdapter.swapCursor(null);
}
}
答案 0 :(得分:0)
Android框架(android.app
)和Android支持库(android.support.v4.app
)都提供了加载程序。它们不可互换,因此您需要选择使用哪一个,并确保您在给定位置使用的所有组件(例如活动)来自同一个包。
AppCompatActivity
提供了使用它们的能力 - getLoaderManager()
返回框架组件(android.app.LoaderManager
),而getSupportLoaderManager()
返回支持库组件(android.support.v4.app.LoaderManager
)。
正如您在评论中提到的那样,您正在从支持库导入LoaderManager.LoaderCallbacks
组件。我认为您遇到的问题是您正在尝试将其与框架中的LoaderManager
组件一起使用(通过getLoaderManager()
)。
尝试将getLoaderManager()
更改为getSupportLoaderManager()
。或者,如果由于某种原因您不想使用支持库,则需要导入android.app.LoaderManager
。