Java tutorial
/* * Copyright 2013 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 ua.org.gdg.devfest.iosched.ui; import ua.org.gdg.devfest.iosched.R; import ua.org.gdg.devfest.iosched.provider.ScheduleContract; import ua.org.gdg.devfest.iosched.social.Tweet; import ua.org.gdg.devfest.iosched.util.UIUtils; import android.content.Context; import android.content.Intent; import android.database.Cursor; import android.net.Uri; import android.os.Bundle; 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.support.v4.widget.CursorAdapter; import android.util.TypedValue; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.AbsListView; import android.widget.ListView; import java.util.HashMap; import java.util.Map; import static ua.org.gdg.devfest.iosched.util.LogUtils.LOGE; import static ua.org.gdg.devfest.iosched.util.LogUtils.makeLogTag; /** * A fragment that shows announcements. */ public class AnnouncementsFragment extends ListFragment implements AbsListView.OnScrollListener, LoaderManager.LoaderCallbacks<Cursor> { private static final String TAG = makeLogTag(AnnouncementsFragment.class); public static final String EXTRA_ADD_VERTICAL_MARGINS = "ua.org.gdg.devfest.iosched.extra.ADD_VERTICAL_MARGINS"; private static final String STATE_POSITION = "position"; private static final String STATE_TOP = "top"; private Cursor mCursor; private StreamAdapter mStreamAdapter; private int mListViewStatePosition; private int mListViewStateTop; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mCursor = null; mStreamAdapter = new StreamAdapter(getActivity()); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { if (savedInstanceState != null) { mListViewStatePosition = savedInstanceState.getInt(STATE_POSITION, -1); mListViewStateTop = savedInstanceState.getInt(STATE_TOP, 0); } else { mListViewStatePosition = -1; mListViewStateTop = 0; } return super.onCreateView(inflater, container, savedInstanceState); } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); setEmptyText(getString(R.string.empty_announcements)); getLoaderManager().initLoader(0, null, this); } @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); final ListView listView = getListView(); if (!UIUtils.isTablet(getActivity())) { view.setBackgroundColor(getResources().getColor(R.color.stream_spacer_color)); } if (getArguments() != null && getArguments().getBoolean(EXTRA_ADD_VERTICAL_MARGINS, false)) { int verticalMargin = getResources().getDimensionPixelSize(R.dimen.social_stream_padding_vertical); if (verticalMargin > 0) { listView.setClipToPadding(false); listView.setPadding(0, verticalMargin, 0, verticalMargin); } } listView.setOnScrollListener(this); listView.setDrawSelectorOnTop(true); listView.setDivider(getResources().getDrawable(android.R.color.transparent)); listView.setDividerHeight(getResources().getDimensionPixelSize(R.dimen.page_margin_width)); TypedValue v = new TypedValue(); getActivity().getTheme().resolveAttribute(R.attr.activatableItemBackground, v, true); listView.setSelector(v.resourceId); setListAdapter(mStreamAdapter); } @Override public void onSaveInstanceState(Bundle outState) { if (isAdded()) { View v = getListView().getChildAt(0); int top = (v == null) ? 0 : v.getTop(); outState.putInt(STATE_POSITION, getListView().getFirstVisiblePosition()); outState.putInt(STATE_TOP, top); } super.onSaveInstanceState(outState); } @Override public void onListItemClick(ListView l, View v, int position, long id) { if (mCursor == null) { return; } mCursor.moveToPosition(position); String url = mCursor.getString(AnnouncementsQuery.ANNOUNCEMENT_URL); Intent postDetailIntent = new Intent(Intent.ACTION_VIEW, Uri.parse(url)); postDetailIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET); UIUtils.preferPackageForIntent(getActivity(), postDetailIntent, UIUtils.TWITTER_PACKAGE_NAME); startActivity(postDetailIntent); } @Override public void onScrollStateChanged(AbsListView listView, int scrollState) { // Pause disk cache access to ensure smoother scrolling if (scrollState == AbsListView.OnScrollListener.SCROLL_STATE_FLING) { // mImageLoader.stopProcessingQueue(); } else { // TODO : Look at image loading mImageLoader.startProcessingQueue(); } } @Override public void onScroll(AbsListView absListView, int i, int i2, int i3) { } @Override public Loader<Cursor> onCreateLoader(int id, Bundle args) { return new CursorLoader(getActivity(), ScheduleContract.Announcements.CONTENT_URI, AnnouncementsQuery.PROJECTION, null, null, ScheduleContract.Announcements.DEFAULT_SORT); } @Override public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) { mCursor = cursor; mStreamAdapter.changeCursor(mCursor); mStreamAdapter.notifyDataSetChanged(); if (mListViewStatePosition != -1 && isAdded()) { getListView().setSelectionFromTop(mListViewStatePosition, mListViewStateTop); mListViewStatePosition = -1; } } @Override public void onLoaderReset(Loader<Cursor> loader) { } private class StreamAdapter extends CursorAdapter { // private JsonFactory mFactory = new AndroidJsonFactory(); private Map<Long, Tweet> mActivityCache = new HashMap<Long, Tweet>(); public StreamAdapter(Context context) { super(context, null, 0); } @Override public View newView(Context context, Cursor cursor, ViewGroup container) { return LayoutInflater.from(getActivity()).inflate(R.layout.list_item_stream_activity, container, false); } @Override public void bindView(View view, Context context, Cursor cursor) { /* Replace with handling tweets long id = cursor.getLong(AnnouncementsQuery._ID); String activityJson = cursor.getString(AnnouncementsQuery.ANNOUNCEMENT_ACTIVITY_JSON); Activity activity = mActivityCache.get(id); // TODO: this should be async if (activity == null) { try { activity = mFactory.fromString(activityJson, Activity.class); } catch (IOException e) { LOGE(TAG, "Couldn't parse activity JSON: " + activityJson, e); } mActivityCache.put(id, activity); } */ } } private interface AnnouncementsQuery { String[] PROJECTION = { ScheduleContract.Announcements._ID, ScheduleContract.Announcements.ANNOUNCEMENT_ACTIVITY_JSON, ScheduleContract.Announcements.ANNOUNCEMENT_URL, }; int _ID = 0; int ANNOUNCEMENT_ACTIVITY_JSON = 1; int ANNOUNCEMENT_URL = 2; } }