Java tutorial
/* * Copyright (C) 2014 The Android Open Source Project * * 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.aafr.alfonso.sunshine.app; import android.app.AlarmManager; import android.app.PendingIntent; 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.Fragment; import android.support.v4.app.LoaderManager.LoaderCallbacks; import android.support.v4.content.CursorLoader; 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.AdapterView; import android.widget.ListView; import com.aafr.alfonso.sunshine.app.data.WeatherContract; import com.aafr.alfonso.sunshine.app.data.WeatherContract.LocationEntry; import com.aafr.alfonso.sunshine.app.data.WeatherContract.WeatherEntry; import com.aafr.alfonso.sunshine.app.service.SunshineService; import java.util.Date; /** * Encapsulates fetching the forecast and displaying it as a {@link android.widget.ListView} layout. */ public class ForecastFragment extends Fragment implements LoaderCallbacks<Cursor> { private ForecastAdapter mForecastAdapter; private String mLocation; private ListView mListView; private int mPosition = ListView.INVALID_POSITION; private boolean mUseTodayLayout; private static final String SELECTED_KEY = "selected_position"; private static final int FORECAST_LOADER = 0; // For the forecast view we're showing only a small subset of the stored data. // Specify the columns we need. private static final String[] FORECAST_COLUMNS = { // In this case the id needs to be fully qualified with a table name, since // the content provider joins the location & weather tables in the background // (both have an _id column) // On the one hand, that's annoying. On the other, you can search the weather table // using the location set by the user, which is only in the Location table. // So the convenience is worth it. WeatherEntry.TABLE_NAME + "." + WeatherEntry._ID, WeatherEntry.COLUMN_DATETEXT, WeatherEntry.COLUMN_SHORT_DESC, WeatherEntry.COLUMN_MAX_TEMP, WeatherEntry.COLUMN_MIN_TEMP, LocationEntry.COLUMN_LOCATION_SETTING, WeatherEntry.COLUMN_WEATHER_ID }; // These indices are tied to FORECAST_COLUMNS. If FORECAST_COLUMNS changes, these // must change. public static final int COL_WEATHER_ID = 0; public static final int COL_WEATHER_DATE = 1; public static final int COL_WEATHER_DESC = 2; public static final int COL_WEATHER_MAX_TEMP = 3; public static final int COL_WEATHER_MIN_TEMP = 4; public static final int COL_LOCATION_SETTING = 5; public static final int COL_WEATHER_CONDITION_ID = 6; /** * A callback interface that all activities containing this fragment must * implement. This mechanism allows activities to be notified of item * selections. */ public interface Callback { /** * DetailFragmentCallback for when an item has been selected. */ public void onItemSelected(String date); } public ForecastFragment() { } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Add this line in order for this fragment to handle menu events. setHasOptionsMenu(true); } @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { inflater.inflate(R.menu.forecastfragment, menu); } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); if (id == R.id.action_refresh) { updateWeather(); return true; } return super.onOptionsItemSelected(item); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // The ArrayAdapter will take data from a source and // use it to populate the ListView it's attached to. mForecastAdapter = new ForecastAdapter(getActivity(), null, 0); View rootView = inflater.inflate(R.layout.fragment_main, container, false); // Get a reference to the ListView, and attach this adapter to it. mListView = (ListView) rootView.findViewById(R.id.listview_forecast); mListView.setAdapter(mForecastAdapter); mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) { Cursor cursor = mForecastAdapter.getCursor(); if (cursor != null && cursor.moveToPosition(position)) { ((Callback) getActivity()).onItemSelected(cursor.getString(COL_WEATHER_DATE)); } mPosition = position; } }); // If there's instance state, mine it for useful information. // The end-goal here is that the user never knows that turning their device sideways // does crazy lifecycle related things. It should feel like some stuff stretched out, // or magically appeared to take advantage of room, but data or place in the app was never // actually *lost*. if (savedInstanceState != null && savedInstanceState.containsKey(SELECTED_KEY)) { // The listview probably hasn't even been populated yet. Actually perform the // swapout in onLoadFinished. mPosition = savedInstanceState.getInt(SELECTED_KEY); } mForecastAdapter.setUseTodayLayout(mUseTodayLayout); return rootView; } @Override public void onActivityCreated(Bundle savedInstanceState) { getLoaderManager().initLoader(FORECAST_LOADER, null, this); super.onActivityCreated(savedInstanceState); } private void updateWeather() { Intent alarmIntent = new Intent(getActivity(), SunshineService.AlarmReceiver.class); alarmIntent.putExtra(SunshineService.LOCATION_QUERY_EXTRA, Utility.getPreferredLocation(getActivity())); //Wrap in a pending intent which only fires once. PendingIntent pi = PendingIntent.getBroadcast(getActivity(), 0, alarmIntent, PendingIntent.FLAG_ONE_SHOT);//getBroadcast(context, 0, i, 0); AlarmManager am = (AlarmManager) getActivity().getSystemService(Context.ALARM_SERVICE); //Set the AlarmManager to wake up the system. am.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + 5000, pi); } @Override public void onResume() { super.onResume(); if (mLocation != null && !mLocation.equals(Utility.getPreferredLocation(getActivity()))) { getLoaderManager().restartLoader(FORECAST_LOADER, null, this); } } @Override public void onSaveInstanceState(Bundle outState) { // When tablets rotate, the currently selected list item needs to be saved. // When no item is selected, mPosition will be set to Listview.INVALID_POSITION, // so check for that before storing. if (mPosition != ListView.INVALID_POSITION) { outState.putInt(SELECTED_KEY, mPosition); } super.onSaveInstanceState(outState); } @Override public Loader<Cursor> onCreateLoader(int id, Bundle args) { // This is called when a new Loader needs to be created. This // fragment only uses one loader, so we don't care about checking the id. // To only show current and future dates, get the String representation for today, // and filter the query to return weather only for dates after or including today. // Only return data after today. String startDate = WeatherContract.getDbDateString(new Date()); // Sort order: Ascending, by date. String sortOrder = WeatherEntry.COLUMN_DATETEXT + " ASC"; mLocation = Utility.getPreferredLocation(getActivity()); Uri weatherForLocationUri = WeatherEntry.buildWeatherLocationWithStartDate(mLocation, startDate); // Now create and return a CursorLoader that will take care of // creating a Cursor for the data being displayed. return new CursorLoader(getActivity(), weatherForLocationUri, FORECAST_COLUMNS, null, null, sortOrder); } @Override public void onLoadFinished(Loader<Cursor> loader, Cursor data) { mForecastAdapter.swapCursor(data); if (mPosition != ListView.INVALID_POSITION) { // If we don't need to restart the loader, and there's a desired position to restore // to, do so now. mListView.smoothScrollToPosition(mPosition); } } @Override public void onLoaderReset(Loader<Cursor> loader) { mForecastAdapter.swapCursor(null); } public void setUseTodayLayout(boolean useTodayLayout) { mUseTodayLayout = useTodayLayout; if (mForecastAdapter != null) { mForecastAdapter.setUseTodayLayout(mUseTodayLayout); } } }