Java tutorial
/* * Copyright (C) 2010 - 2013 Niall 'Rivernile' Scott * * This software is provided 'as-is', without any express or implied * warranty. In no event will the authors or contributors be held liable for * any damages arising from the use of this software. * * The aforementioned copyright holder(s) hereby grant you a * non-transferrable right to use this software for any purpose (including * commercial applications), and to modify it and redistribute it, subject to * the following conditions: * * 1. This notice may not be removed or altered from any file it appears in. * * 2. Any modifications made to this software, except those defined in * clause 3 of this agreement, must be released under this license, and * the source code of any modifications must be made available on a * publically accessible (and locateable) website, or sent to the * original author of this software. * * 3. Software modifications that do not alter the functionality of the * software but are simply adaptations to a specific environment are * exempt from clause 2. */ package uk.org.rivernile.edinburghbustracker.android.fragments.general; import static uk.org.rivernile.edinburghbustracker.android.twitter.TwitterUpdatesLoader.ERROR_NODATA; import static uk.org.rivernile.edinburghbustracker.android.twitter.TwitterUpdatesLoader.ERROR_PARSEERR; import static uk.org.rivernile.edinburghbustracker.android.twitter.TwitterUpdatesLoader.ERROR_IOERR; import static uk.org.rivernile.edinburghbustracker.android.twitter.TwitterUpdatesLoader.ERROR_URLERR; import static uk.org.rivernile.edinburghbustracker.android.twitter.TwitterUpdatesLoader.ERROR_URLMISMATCH; import android.content.Context; import android.os.Bundle; import android.support.v4.app.ListFragment; import android.support.v4.app.LoaderManager; import android.support.v4.content.Loader; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; import android.widget.SimpleAdapter; import android.widget.TextView; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import uk.org.rivernile.edinburghbustracker.android.R; import uk.org.rivernile.edinburghbustracker.android.twitter.TwitterLoaderResult; import uk.org.rivernile.edinburghbustracker.android.twitter.TwitterNewsItem; import uk.org.rivernile.edinburghbustracker.android.twitter.TwitterUpdatesLoader; /** * This Fragments displays a ListView of Tweets which informs users of things * that may affect their journey. No action can be taken on the ListView items * but URLs can be tapped. * * @author Niall Scott */ public class TwitterUpdatesFragment extends ListFragment implements LoaderManager.LoaderCallbacks<TwitterLoaderResult> { private View progress; private TextView txtError; /** * {@inheritDoc} */ @Override public View onCreateView(final LayoutInflater inflater, final ViewGroup container, final Bundle savedInstanceState) { final View v = inflater.inflate(R.layout.newsupdates, container, false); progress = v.findViewById(R.id.progress); txtError = (TextView) v.findViewById(R.id.txtError); return v; } /** * {@inheritDoc} */ @Override public void onActivityCreated(final Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); // Tell the underlying Activity that it should create an options menu // for this Fragment. setHasOptionsMenu(true); // Initialise the Loader for loading tweets. getLoaderManager().initLoader(0, null, this); } /** * {@inheritDoc} */ @Override public void onCreateOptionsMenu(final Menu menu, final MenuInflater inflater) { // Inflate the options menu. inflater.inflate(R.menu.newsupdates_option_menu, menu); } /** * {@inheritDoc} */ @Override public void onPrepareOptionsMenu(final Menu menu) { super.onPrepareOptionsMenu(menu); final MenuItem refreshItem = menu.findItem(R.id.newsupdates_option_menu_refresh); if (progress.getVisibility() == View.VISIBLE) { // Disable the refresh item if a refresh is in progress. refreshItem.setEnabled(false); } else { // Enable the refresh item otherwise. refreshItem.setEnabled(true); } } /** * {@inheritDoc} */ @Override public boolean onOptionsItemSelected(final MenuItem item) { switch (item.getItemId()) { case R.id.newsupdates_option_menu_refresh: // Fetch the data. getLoaderManager().restartLoader(0, null, this); return true; default: return super.onOptionsItemSelected(item); } } /** * {@inheritDoc} */ @Override public Loader<TwitterLoaderResult> onCreateLoader(final int id, final Bundle args) { showProgress(); return new TwitterUpdatesLoader(getActivity()); } /** * {@inheritDoc} */ @Override public void onLoadFinished(final Loader<TwitterLoaderResult> loader, final TwitterLoaderResult result) { if (isAdded()) { if (result.hasError()) { handleError(result.getError()); } else { populateList(result.getResult()); } } } /** * {@inheritDoc} */ @Override public void onLoaderReset(final Loader<TwitterLoaderResult> loader) { // Nothing to do here. } /** * Show the user progress on loading. */ private void showProgress() { // Empty the ListView. setListAdapter(null); // Show the progress. txtError.setVisibility(View.GONE); progress.setVisibility(View.VISIBLE); // Invalidate so that the refresh item gets disabled. getActivity().supportInvalidateOptionsMenu(); } /** * Handle error codes. * * @param errorCode The error code. */ private void handleError(final int errorCode) { // Set the TextView depending on what the error code is. switch (errorCode) { case ERROR_NODATA: txtError.setText(R.string.newsupdates_err_nodata); break; case ERROR_PARSEERR: txtError.setText(R.string.newsupdates_err_parseerr); break; case ERROR_IOERR: txtError.setText(R.string.newsupdates_err_ioerr); break; case ERROR_URLERR: txtError.setText(R.string.newsupdates_err_urlerr); break; case ERROR_URLMISMATCH: txtError.setText(R.string.newsupdates_err_urlmismatch); break; } // Show the error layout. progress.setVisibility(View.GONE); txtError.setVisibility(View.VISIBLE); // Invalidate the options menu so that the refresh item is shown again. getActivity().supportInvalidateOptionsMenu(); } /** * Populate the ListView with the Twitter news items. * * @param items An ArrayList of {@link TwitterNewsItem}s. */ private void populateList(final ArrayList<TwitterNewsItem> items) { // If there's 0 items, display an error. if (items == null || items.isEmpty()) { handleError(ERROR_NODATA); return; } // Ensure that the progress and error layouts are removed. txtError.setVisibility(View.GONE); progress.setVisibility(View.GONE); // Fun and magic happens here. final ArrayList<HashMap<String, String>> list = new ArrayList<HashMap<String, String>>(); HashMap<String, String> map; for (TwitterNewsItem item : items) { map = new HashMap<String, String>(); map.put("TEXT", item.getBody()); map.put("INFO", item.getPoster() + " - " + item.getDate()); list.add(map); } // Create the ListAdapter. final NewsItemsAdapter adapter = new NewsItemsAdapter(getActivity(), list, R.layout.newsupdateslist, new String[] { "TEXT", "INFO" }, new int[] { R.id.twitText, R.id.twitInfo }); setListAdapter(adapter); // Invalidate the options menu to make sure that the refresh item is // shown. getActivity().supportInvalidateOptionsMenu(); } /** * This is the ListAdapter which is used to display the Twitter items. */ private static class NewsItemsAdapter extends SimpleAdapter { /** * {@inheritDoc} */ public NewsItemsAdapter(final Context context, final List<? extends Map<String, ?>> data, final int resource, final String[] from, final int[] to) { super(context, data, resource, from, to); } /** * {@inheritDoc} */ @Override public boolean isEnabled(final int index) { return false; } } }