I have a blank recycler view inside a fragment. Upon receiving a GCM notification, I like to call a webservice. That webservice will store data into a blank database. When this is all done, how do I notify the recycler view to update itself with the new database content?
I am only stuck at the portion where I need to notify recycler view somehow to update itself. I implemented this https://gist.github.com/skyfishjy/443b7448f59be978bc59 , but it works only when there is data already in database. It does not work in my scenario.
I am providing the code I have currently for better understanding of the problem:
package mypackage;
import android.app.Activity;
import android.app.LoaderManager;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.CursorLoader;
import android.content.Loader;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.OvershootInterpolator;
import com.squareup.picasso.Picasso;
import mypackage.R;
import mypackage.adapters.NewsRecyclerViewAdapter;
import mypackage.database.NewsProvider;
import mypackage.models.News;
import mypackage.utils.SaveImageTask;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.Random;
import butterknife.ButterKnife;
import jp.wasabeef.recyclerview.animators.FlipInRightYAnimator;
import jp.wasabeef.recyclerview.animators.adapters.AlphaInAnimationAdapter;
import jp.wasabeef.recyclerview.animators.adapters.ScaleInAnimationAdapter;
import static mypackage.MyDbOpenHelper.*;
public class NewsListFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor> {
private NewsRecyclerViewAdapter mAdapter;
private SaveImageTask saveImageTask;
private NewsType newsType;
private Activity parent;
public static NewsListFragment newInstance(NewsType newsType, Activity container) {
NewsListFragment fragment = new NewsListFragment();
fragment.saveImageTask = new SaveImageTask(container);
fragment.newsType = newsType;
fragment.parent = container;
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
final Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.recycler_view, container, false);
ButterKnife.bind(this, view);
final RecyclerView mRecyclerView = (RecyclerView) view.findViewById(R.id.my_recycler_view);
mRecyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(view.getContext());
mRecyclerView.setLayoutManager(mLayoutManager);
Picasso picasso = new Picasso.Builder(parent).build();
ContentResolver contentResolver = parent.getContentResolver();
Cursor newsCursor;
if (newsType == NewsType.ALL) {
newsCursor = contentResolver.query(NewsProvider.CONTENT_URI, null, null, null, null);
} else {
newsCursor = contentResolver.query(SavedNewsProvider.CONTENT_URI, null, null, null, null);
}
mAdapter = new NewsRecyclerViewAdapter(newsCursor);
mAdapter.setPicasso(picasso);
AlphaInAnimationAdapter alphaAdapter = new AlphaInAnimationAdapter(mAdapter);
ScaleInAnimationAdapter scaleAdapter = new ScaleInAnimationAdapter(alphaAdapter);
scaleAdapter.setFirstOnly(false);
scaleAdapter.setInterpolator(new OvershootInterpolator());
mRecyclerView.setItemAnimator(new FlipInRightYAnimator());
mRecyclerView.getItemAnimator().setAddDuration(300);
mRecyclerView.setAdapter(scaleAdapter);
ViewCompat.setElevation(view, 50);
parent.getLoaderManager().initLoader(0, null, this);
new AsyncTask<Void, Void, Void>() {
@Override
protected Void doInBackground(Void... params) {
Cursor news = parent.getContentResolver().query(NewsProvider.CONTENT_URI,
null, null, null, null);
if (news == null || news.getCount() == 0) {
insertNewsList();
} else {
news.close();
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
parent.getLoaderManager().restartLoader(0, null, NewsListFragment.this);
mAdapter.notifyDataSetChanged();
ContentResolver.requestSync(null, NewsProvider.AUTHORITY, new Bundle());
mRecyclerView.refreshDrawableState();
mRecyclerView.postInvalidate();
}
}.execute(null, null, null);
return view;
}
private void insertNewsList() {
String[] titles = {"Web", "Java", "Android"};
Random random = new Random(Calendar.getInstance().getTimeInMillis());
for (String title : titles) {
int count = random.nextInt(20);
List<News> newsList = generateDataSet(title, count);
for (News dataObject : newsList) {
ContentValues initialValues = new ContentValues();
initialValues.put(NEWS_IMAGE_LINK, dataObject.getTopImageLink());
initialValues.put(NEWS_IMAGE_PATH, dataObject.getTopImagePath());
initialValues.put(NEWS_LINK, dataObject.getLink());
initialValues.put(NEWS_SOURCE, dataObject.getSourceText());
initialValues.put(NEWS_SOURCE_IMG_LINK, dataObject.getSourceImageLink());
initialValues.put(NEWS_SOURCE_IMG_PATH, dataObject.getSourceImagePath());
initialValues.put(NEWS_TAGS, Arrays.toString(dataObject.getTag()));
initialValues.put(NEWS_TEXT, dataObject.getText());
initialValues.put(NEWS_TIME, getDateTime());
initialValues.put(NEWS_TITLE, dataObject.getTitle());
parent.getContentResolver().insert(NewsProvider.CONTENT_URI, initialValues);
}
}
}
@Override
public void onDestroy() {
super.onDestroy();
}
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
return new CursorLoader(parent, NewsProvider.CONTENT_URI, null, null, null, null);
}
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
mAdapter.swapCursor(data);
}
@Override
public void onLoaderReset(Loader<Cursor> loader) {
mAdapter.swapCursor(null);
}
private List<News> generateDataSet(String subject, int count) {
String title = "Neque porro quisquam est qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit...";
String text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Pellentesque porttitor nulla nec nulla fermentum, " +
"quis imperdiet ipsum aliquet. Phasellus quis odio sit amet nulla rutrum porta. Quisque in ultrices metus." +
" Aliquam gravida et lacus ac vestibulum.";
String topImageLink = "http://lorempixel.com/1024/768/";
String[] categories = {"abstract", "city", "people", "transport", "animals",
"food", "nature", "business", "nightlife", "sports", "cats", "fashion", "technics"};
String sourceImageLink = "http://thegg.net/wp-content/themes/Orizon/css/blue_css/images/rss-icon.png";
String sourceText = "Random Blog";
String link = "http://www.google.com";
List<News> results = new ArrayList<>();
for (int index = 0; index < count; index++) {
int imgIndex = index % 12;
String imgText = subject + "-card-" + index;
String newTitle = imgText + " " + title;
News obj = new News(newTitle);
if (index % 2 == 0) {
obj.setText(text);
} else {
obj.setTopImageLink(topImageLink + categories[imgIndex] + "/" + imgText);
}
if (index % 5 != 0) {
obj.setSourceImageLink(sourceImageLink);
obj.setSourceText(sourceText);
}
if (index % 7 == 0) {
obj.setText(text);
obj.setTopImageLink(topImageLink + categories[imgIndex] + "/" + imgText);
obj.setSourceImageLink(sourceImageLink);
obj.setSourceText(sourceText);
}
if (obj.getTopImageLink() != null && !"".equalsIgnoreCase(obj.getTopImageLink())) {
Uri topImageUri = saveImageTask.saveImageFile(obj.getTopImageLink());
obj.setTopImagePath(topImageUri.getPath());
}
if (obj.getSourceImageLink() != null && !"".equalsIgnoreCase(obj.getSourceImageLink())) {
Uri sourceImageUri = saveImageTask.saveImageFile(obj.getSourceImageLink());
obj.setSourceImagePath(sourceImageUri.getPath());
}
obj.setLink(link);
obj.setTag(new String[] {subject});
results.add(index, obj);
}
return results;
}
private String getDateTime() {
SimpleDateFormat dateFormat = new SimpleDateFormat(
"yyyy-MM-dd HH:mm:ss", Locale.getDefault());
Date date = new Date();
return dateFormat.format(date);
}
public enum NewsType {
ALL,
FAVORITE
}
}
My ContentProvider
package mypackage.database;
import android.content.ContentProvider;
import android.content.ContentValues;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
public abstract class NewsProvider extends ContentProvider {
public static final String AUTHORITY = "myapp.data.newsprovider";
private static final String BASE_PATH = "news";
public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/" + BASE_PATH );
// Constant to identify the requested operation
private static final int NEWS = 1;
private static final int NEWS_ID = 2;
private static final int NEWS_TAG = 3;
private static final UriMatcher uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
static {
uriMatcher.addURI(AUTHORITY, BASE_PATH, NEWS);
uriMatcher.addURI(AUTHORITY, BASE_PATH + "/#", NEWS_ID);
uriMatcher.addURI(AUTHORITY, BASE_PATH + "/tag/*", NEWS_TAG);
}
private String tableName;
private String basePath;
protected SQLiteDatabase database;
public NewsProvider() {
this.tableName = TABLE_NEWS;
this.basePath = BASE_PATH;
}
@Override
public boolean onCreate() {
MyDbOpenHelper helper = new MyDbOpenHelper(getContext());
database = helper.getWritableDatabase();
return true;
}
@Override
public String getType(Uri uri) {
return null;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
if (uriMatcher.match(uri) == NEWS_ID) {
selection = NEWS_ID + "=" + uri.getLastPathSegment();
}
if (uriMatcher.match(uri) == NEWS_TAG) {
selection = NEWS_TAGS + " like %'" + uri.getLastPathSegment() + "'%";
}
return database.query(TABLE_NEWS, NEWS_ALL_COLUMNS,
selection, null, null, null, NEWS_TIME + " DESC");
}
@Override
public Uri insert(Uri uri, ContentValues values) {
long id = database.insert(tableName, null, values);
Uri newUri = Uri.parse(basePath + "/" + id);
getContext().getContentResolver().notifyChange(newUri, null);
return newUri;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
return database.delete(tableName, selection, selectionArgs);
}
@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
return database.update(tableName, values, selection, selectionArgs);
}
}
I am only stuck at the portion where I need to notify recycler view somehow to update itself. I implemented this https://gist.github.com/skyfishjy/443b7448f59be978bc59 , but it works only when there is data already in database. It does not work in my scenario.
If you have a ContentProvider
and you are using a CursorLoader , upon notify of the correct Uri
, the framework should query the database again. If you are not using a ContentProvider, you could use the LocalBroadcastManger , to broadcast an event after the insertion of new data in the database. The Fragment should register to this event and re-query the database manually
您可以使用EventBus将消息发送到适配器以调用notifyDataSetChange
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