Java tutorial
/* * Copyright 2012 Google Inc. * * 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 com.conferenceengineer.android.iosched.ui; import android.app.Activity; import android.content.Intent; import android.database.ContentObserver; import android.database.Cursor; import android.database.DataSetObserver; import android.graphics.Color; import android.net.Uri; import android.os.Bundle; import android.os.Handler; import android.support.v4.app.ListFragment; import android.support.v4.app.LoaderManager; import android.support.v4.content.CursorLoader; import android.support.v4.content.Loader; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ListView; import com.conferenceengineer.android.iosched.conference686.R; import com.conferenceengineer.android.iosched.provider.ScheduleContract; import com.conferenceengineer.android.iosched.ui.TracksAdapter.TracksQuery; import com.conferenceengineer.android.iosched.ui.tablet.SessionsSandboxMultiPaneActivity; import com.conferenceengineer.android.iosched.ui.tablet.TracksDropdownFragment; /** * A simple {@link ListFragment} that renders a list of tracks with available * sessions or sandbox companies (depending on {@link ExploreFragment#VIEW_TYPE}) using a * {@link TracksAdapter}. */ public class ExploreFragment extends ListFragment implements LoaderManager.LoaderCallbacks<Cursor> { private TracksAdapter mAdapter; private View mEmptyView; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.fragment_list_with_empty_container_inset, container, false); mEmptyView = rootView.findViewById(android.R.id.empty); inflater.inflate(R.layout.empty_waiting_for_sync, (ViewGroup) mEmptyView, true); return rootView; } @Override public void onViewCreated(final View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); view.setBackgroundColor(Color.WHITE); final ListView listView = getListView(); listView.setSelector(android.R.color.transparent); listView.setCacheColorHint(Color.WHITE); mAdapter = new TracksAdapter(getActivity(), false); setListAdapter(mAdapter); // Override default ListView empty-view handling listView.setEmptyView(null); mEmptyView.setVisibility(View.VISIBLE); mAdapter.registerDataSetObserver(new DataSetObserver() { @Override public void onChanged() { if (mAdapter.getCount() > 0) { mEmptyView.setVisibility(View.GONE); mAdapter.unregisterDataSetObserver(this); } } }); } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); // As of support library r12, calling initLoader for a fragment in a FragmentPagerAdapter // in the fragment's onCreate may cause the same LoaderManager to be dealt to multiple // fragments because their mIndex is -1 (haven't been added to the activity yet). Thus, // we do this in onActivityCreated. getLoaderManager().initLoader(TracksQuery._TOKEN, null, this); } private final ContentObserver mObserver = new ContentObserver(new Handler()) { @Override public void onChange(boolean selfChange) { if (getActivity() == null) { return; } getLoaderManager().restartLoader(TracksQuery._TOKEN, null, ExploreFragment.this); } }; @Override public void onAttach(Activity activity) { super.onAttach(activity); activity.getContentResolver().registerContentObserver(ScheduleContract.Sessions.CONTENT_URI, true, mObserver); } @Override public void onDetach() { super.onDetach(); getActivity().getContentResolver().unregisterContentObserver(mObserver); } /** {@inheritDoc} */ @Override public void onListItemClick(ListView l, View v, int position, long id) { final Cursor cursor = (Cursor) mAdapter.getItem(position); String trackId = ScheduleContract.Tracks.ALL_TRACK_ID; int trackMeta = ScheduleContract.Tracks.TRACK_META_NONE; if (cursor != null) { trackId = cursor.getString(TracksAdapter.TracksQuery.TRACK_ID); trackMeta = cursor.getInt(TracksAdapter.TracksQuery.TRACK_META); } final Intent intent = new Intent(Intent.ACTION_VIEW); final Uri trackUri = ScheduleContract.Tracks.buildTrackUri(trackId); intent.setData(trackUri); if (trackMeta == ScheduleContract.Tracks.TRACK_META_SANDBOX_OFFICE_HOURS_ONLY) { intent.putExtra(SessionsSandboxMultiPaneActivity.EXTRA_DEFAULT_VIEW_TYPE, TracksDropdownFragment.VIEW_TYPE_SANDBOX); } else if (trackMeta == ScheduleContract.Tracks.TRACK_META_OFFICE_HOURS_ONLY) { intent.putExtra(SessionsSandboxMultiPaneActivity.EXTRA_DEFAULT_VIEW_TYPE, TracksDropdownFragment.VIEW_TYPE_OFFICE_HOURS); } startActivity(intent); } @Override public Loader<Cursor> onCreateLoader(int id, Bundle data) { Intent intent = BaseActivity.fragmentArgumentsToIntent(getArguments()); Uri tracksUri = intent.getData(); if (tracksUri == null) { tracksUri = ScheduleContract.Tracks.CONTENT_URI; } // Filter our tracks query to only include those with valid results String[] projection = TracksAdapter.TracksQuery.PROJECTION; String selection = null; return new CursorLoader(getActivity(), tracksUri, projection, selection, null, ScheduleContract.Tracks.DEFAULT_SORT); } @Override public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) { if (getActivity() == null) { return; } mAdapter.setHasAllItem(true); mAdapter.swapCursor(cursor); if (cursor.getCount() > 0) { mEmptyView.setVisibility(View.GONE); } } @Override public void onLoaderReset(Loader<Cursor> loader) { } }