Java tutorial
/* * Copyright 2011 Peter Kuterna * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package net.peterkuterna.android.apps.devoxxfrsched.ui; import net.peterkuterna.android.apps.devoxxfrsched.R; import net.peterkuterna.android.apps.devoxxfrsched.provider.CfpContract; import net.peterkuterna.android.apps.devoxxfrsched.provider.CfpContract.News; import net.peterkuterna.android.apps.devoxxfrsched.util.AnalyticsUtils; import net.peterkuterna.android.apps.devoxxfrsched.util.NotifierManager; import net.peterkuterna.android.apps.devoxxfrsched.util.NotifyingAsyncQueryHandler; import android.content.ContentValues; import android.content.Context; import android.database.ContentObserver; import android.database.Cursor; import android.net.Uri; import android.os.Bundle; import android.os.Handler; import android.provider.BaseColumns; import android.support.v4.app.LoaderManager; import android.support.v4.content.CursorLoader; import android.support.v4.content.Loader; import android.support.v4.widget.CursorAdapter; import android.text.format.DateUtils; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.TextView; import com.actionbarsherlock.app.SherlockListFragment; public class BulletinFragment extends SherlockListFragment implements LoaderManager.LoaderCallbacks<Cursor> { protected static final String TAG = "BulletinFragment"; private NotifyingAsyncQueryHandler mQueryHandler; private NotifierManager mNotifierManager; private BulletinAdapter mAdapter; private Handler mHandler = new Handler(); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); AnalyticsUtils.getInstance(getActivity()).trackPageView("/Bulletin"); } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); mQueryHandler = new NotifyingAsyncQueryHandler(getActivity().getContentResolver(), null); mNotifierManager = new NotifierManager(getActivity()); setEmptyText(getString(R.string.empty_bulletin_results)); mAdapter = new BulletinAdapter(getActivity(), null); setListAdapter(mAdapter); setListShown(false); getLoaderManager().initLoader(NewsQuery._TOKEN, null, this); } @Override public void onResume() { super.onResume(); clearNewNewsItems(); mHandler.postDelayed(mUpdateTimeRunnable, 60 * DateUtils.SECOND_IN_MILLIS); getLoaderManager().restartLoader(NewsQuery._TOKEN, null, this); getActivity().getContentResolver().registerContentObserver(News.CONTENT_URI, true, mNewsChangesObserver); } @Override public void onPause() { super.onPause(); getActivity().getContentResolver().unregisterContentObserver(mNewsChangesObserver); } @Override public Loader<Cursor> onCreateLoader(int id, Bundle args) { return new CursorLoader(getActivity(), News.CONTENT_URI, NewsQuery.PROJECTION, null, null, News.DEFAULT_SORT); } @Override public void onLoadFinished(Loader<Cursor> loader, Cursor data) { mAdapter.swapCursor(data); if (getView() != null) { if (isResumed()) { setListShown(true); } else { setListShownNoAnimation(true); } } } @Override public void onLoaderReset(Loader<Cursor> loader) { mAdapter.swapCursor(null); } private void clearNewNewsItems() { final Uri uri = News.CONTENT_NEW_URI; final ContentValues values = new ContentValues(); values.put(News.NEWS_NEW, 0); mQueryHandler.startUpdate(uri, values); mNotifierManager.clearNewNewsNotification(); } private ContentObserver mNewsChangesObserver = new ContentObserver(new Handler()) { @Override public void onChange(boolean selfChange) { if (getActivity() != null) { getLoaderManager().restartLoader(NewsQuery._TOKEN, null, BulletinFragment.this); } } }; private Runnable mUpdateTimeRunnable = new Runnable() { public void run() { if (mAdapter != null) { mAdapter.notifyDataSetChanged(); } mHandler.postDelayed(mUpdateTimeRunnable, 60 * DateUtils.SECOND_IN_MILLIS); } }; public static final class NewsViews { TextView dateView; TextView textView; } private class BulletinAdapter extends CursorAdapter { private long mCurrentTime = 0; public BulletinAdapter(Context context, Cursor c) { super(context, c, 0); } protected void findAndCacheViews(View view) { NewsViews views = new NewsViews(); views.dateView = (TextView) view.findViewById(android.R.id.text1); views.textView = (TextView) view.findViewById(android.R.id.text2); view.setTag(views); } @Override public View newView(Context context, Cursor cursor, ViewGroup parent) { View v = LayoutInflater.from(context).inflate(R.layout.list_item_bulletin, parent, false); findAndCacheViews(v); return v; } @Override public void bindView(View view, Context context, Cursor cursor) { NewsViews views = (NewsViews) view.getTag(); final long created_at = cursor.getLong(NewsQuery.NEWS_DATE); final CharSequence createdAtRelative = DateUtils.getRelativeTimeSpanString(created_at, created_at > mCurrentTime ? created_at : mCurrentTime, DateUtils.MINUTE_IN_MILLIS, DateUtils.FORMAT_ABBREV_ALL); final String text = cursor.getString(NewsQuery.NEWS_TEXT); views.dateView.setText(createdAtRelative); views.textView.setText(text); } @Override public void notifyDataSetChanged() { mCurrentTime = System.currentTimeMillis(); super.notifyDataSetChanged(); } } /** * {@link News} query parameters. */ public interface NewsQuery { int _TOKEN = 0x1; String[] PROJECTION = { BaseColumns._ID, CfpContract.News.NEWS_CREATED_AT, CfpContract.News.NEWS_TEXT, }; int _ID = 0; int NEWS_DATE = 1; int NEWS_TEXT = 2; } }