Java tutorial
/*- * Copyright (C) 2009 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.google.android.demos.rss.app; import com.google.android.demos.rss.R; import com.google.android.demos.rss.provider.RssContract.Channels; import com.google.android.demos.rss.provider.RssContract.Items; import com.google.android.demos.rss.widget.ChannelAdapter; import com.google.android.demos.rss.widget.ItemDialog; import android.app.Dialog; import android.content.ComponentName; import android.content.Context; import android.content.Intent; import android.database.Cursor; import android.database.DataSetObserver; import android.net.Uri; import android.os.Bundle; import android.support.v4.app.FragmentActivity; import android.support.v4.app.LoaderManager; import android.support.v4.content.Loader; import android.text.Html; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.Window; import android.widget.AdapterView; import android.widget.ListView; import android.widget.SimpleCursorAdapter; import android.widget.TextView; public class ChannelActivity extends FragmentActivity implements LoaderManager.LoaderCallbacks<Cursor>, SimpleCursorAdapter.ViewBinder, AdapterView.OnItemClickListener, View.OnClickListener { private static final String DEFAULT_CHANNEL = "http://feeds.digg.com/digg/popular.rss"; private static final int MENU_GROUP_INTENT_OPTIONS = 1; private static final int DIALOG_ITEM = 1; private static final int LOADER_CHANNEL = 1; private ChannelAdapter mAdapter; private ItemDialog mItemDialog; private View mEmpty; private View mLoading; private View mError; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS); setContentView(R.layout.list_activity); ListView listView = (ListView) findViewById(android.R.id.list); mEmpty = findViewById(R.id.empty); mLoading = findViewById(R.id.loading); mError = findViewById(R.id.error); mError.findViewById(R.id.retry).setOnClickListener(this); // Loader from last Activity instance may still be loading mLoading.setVisibility(View.VISIBLE); mEmpty.setVisibility(View.GONE); mError.setVisibility(View.GONE); Context context = this; int layout = android.R.layout.simple_list_item_1; String[] from = { Items.TITLE }; int[] to = { android.R.id.text1 }; SimpleCursorAdapter innerAdapter = new SimpleCursorAdapter(context, layout, null, from, to); innerAdapter.setViewBinder(this); mAdapter = new ChannelAdapter(this); mAdapter.registerDataSetObserver(new TitleObserver()); listView.setAdapter(mAdapter); listView.setOnItemClickListener(this); getSupportLoaderManager().initLoader(LOADER_CHANNEL, Bundle.EMPTY, this); } /** * {@inheritDoc} */ public Loader<Cursor> onCreateLoader(int id, Bundle args) { mLoading.setVisibility(mAdapter.isEmpty() ? View.VISIBLE : View.GONE); mEmpty.setVisibility(View.GONE); mError.setVisibility(View.GONE); setWindowIndeterminateProgressVisible(!mAdapter.isEmpty()); Context context = this; Uri data = getIntent().getData(); Uri uri = data != null ? data : Items.contentUri(DEFAULT_CHANNEL); return ChannelAdapter.createLoader(context, uri); } /** * {@inheritDoc} */ public void onLoadFinished(Loader<Cursor> loader, Cursor data) { mAdapter.swapCursor(data); mLoading.setVisibility(View.GONE); mEmpty.setVisibility(mAdapter.isEmpty() && !mAdapter.hasError() ? View.VISIBLE : View.GONE); mError.setVisibility(mAdapter.isEmpty() && mAdapter.hasError() ? View.VISIBLE : View.GONE); setWindowIndeterminateProgressVisible(false); } /** * {@inheritDoc} */ public void onLoaderReset(Loader<Cursor> loader) { mAdapter.swapCursor(null); mLoading.setVisibility(View.GONE); mEmpty.setVisibility(View.GONE); mError.setVisibility(View.GONE); setWindowIndeterminateProgressVisible(false); } private void setWindowIndeterminateProgressVisible(boolean value) { getWindow().setFeatureInt(Window.FEATURE_INDETERMINATE_PROGRESS, value ? Window.PROGRESS_VISIBILITY_ON : Window.PROGRESS_VISIBILITY_OFF); } @Override protected Dialog onCreateDialog(int id) { if (id == DIALOG_ITEM) { mItemDialog = new ItemDialog(this); return mItemDialog; } else { return super.onCreateDialog(id); } } public void onItemClick(AdapterView<?> l, View v, int position, long id) { Object item = l.getItemAtPosition(position); Cursor cursor = mAdapter.getCursor(); if (item != null && item == cursor) { showDialog(DIALOG_ITEM); // Assign item data to dialog from cursor ChannelAdapter.setItemData(mItemDialog, cursor); // Scroll to top of item content mItemDialog.scrollToTop(); } } private void addStandardOptionsMenuItems(Menu menu) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.channel_menu, menu); } private void addAlternativeOptionsMenuItems(Menu menu) { int groupId = MENU_GROUP_INTENT_OPTIONS; int itemId = Menu.NONE; int order = Menu.NONE; ComponentName caller = getComponentName(); Intent[] specifics = null; Intent intent = new Intent(); intent.setData(getIntent().getData()); intent.addCategory(Intent.CATEGORY_ALTERNATIVE); int flags = 0; MenuItem[] outSpecificItems = null; menu.addIntentOptions(groupId, itemId, order, caller, specifics, intent, flags, outSpecificItems); } @Override public boolean onCreateOptionsMenu(Menu menu) { super.onCreateOptionsMenu(menu); addStandardOptionsMenuItems(menu); addAlternativeOptionsMenuItems(menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.menu_refresh: reload(); return true; } return false; } /** * {@inheritDoc} */ public boolean setViewValue(View view, Cursor cursor, int columnIndex) { if (android.R.id.text1 == view.getId()) { TextView textView = (TextView) view; String value = cursor.getString(columnIndex); CharSequence text = Html.fromHtml(value); textView.setText(text); return true; } else { return false; } } /** * {@inheritDoc} */ public void onClick(View v) { switch (v.getId()) { case R.id.retry: reload(); break; } } private void reload() { getSupportLoaderManager().restartLoader(LOADER_CHANNEL, Bundle.EMPTY, this); } private final class TitleObserver extends DataSetObserver { @Override public void onChanged() { Cursor cursor = mAdapter.getCursor(); Bundle extras = cursor.getExtras(); String title = extras.getString(Channels.TITLE_PLAINTEXT); if (title != null) { setTitle(title); } } } }