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.kobi.metalsexchange.app; import android.content.Context; import android.content.SharedPreferences; import android.database.Cursor; import android.graphics.Color; import android.net.Uri; import android.os.Bundle; import android.preference.PreferenceManager; import android.support.v4.app.Fragment; import android.support.v4.app.LoaderManager; import android.support.v4.content.CursorLoader; import android.support.v4.content.Loader; import android.support.v4.widget.SwipeRefreshLayout; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; 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.view.animation.Animation; import android.view.animation.AnimationUtils; import android.widget.ImageView; import android.widget.TextView; import com.kobi.metalsexchange.app.component.DividerItemDecoration; import com.kobi.metalsexchange.app.data.MetalsContract; import com.kobi.metalsexchange.app.sync.MetalsExchangeSyncAdapter; /**T * Encapsulates fetching the rates and displaying it as a {@link RecyclerView} layout. */ public class ExchangeRatesFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor>, SharedPreferences.OnSharedPreferenceChangeListener { private ExchangeRatesAdapter mExchangeRatesAdapter; private RecyclerView mRecyclerView; private SwipeRefreshLayout mSwipeRefreshLayout; private int mPosition = RecyclerView.NO_POSITION; private static final String SELECTED_KEY = "selected_position"; private MenuItem refreshItem; private LayoutInflater inflater; private ImageView refreshImageView; private Animation rotation; private static final int RATES_LOADER = 0; private static final String[] RATES_COLUMNS = { MetalsContract.MetalsRateEntry.TABLE_NAME + "." + MetalsContract.MetalsRateEntry._ID, MetalsContract.MetalsRateEntry.COLUMN_DATE, MetalsContract.MetalsRateEntry.COLUMN_METAL_ID, MetalsContract.MetalsRateEntry.COLUMN_ILS_RATE, MetalsContract.MetalsRateEntry.COLUMN_USD_RATE, MetalsContract.MetalsRateEntry.COLUMN_GBP_RATE, MetalsContract.MetalsRateEntry.COLUMN_EUR_RATE, MetalsContract.MetalsRateEntry.COLUMN_CAD_RATE, MetalsContract.MetalsRateEntry.COLUMN_DKK_RATE, MetalsContract.MetalsRateEntry.COLUMN_NOK_RATE, MetalsContract.MetalsRateEntry.COLUMN_SEK_RATE, MetalsContract.MetalsRateEntry.COLUMN_CHF_RATE, MetalsContract.MetalsRateEntry.COLUMN_JOD_RATE, MetalsContract.MetalsRateEntry.COLUMN_EGP_RATE }; // These indices are tied to RATES_COLUMNS. If RATES_COLUMNS changes, these // must change. public static final int COL_RATE_ID = 0; public static final int COL_RATE_DATE = 1; public static final int COL_RATE_METAL_ID = 2; public static final int COL_RATE_ILS = 3; public static final int COL_RATE_USD = 4; public static final int COL_RATE_GBP = 5; public static final int COL_RATE_EUR = 6; public static final int COL_RATE_CAD = 7; public static final int COL_RATE_DKK = 8; public static final int COL_RATE_NOK = 9; public static final int COL_RATE_SEK = 10; public static final int COL_RATE_CHF = 11; public static final int COL_RATE_JOD = 12; public static final int COL_RATE_EGP = 13; /** * 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. */ void onItemSelected(Uri dateUri); } public static final String METAL_ID = "METAL_ID"; private String mMetalId; public static ExchangeRatesFragment newInstance(String metalId) { Bundle args = new Bundle(); args.putString(METAL_ID, metalId); ExchangeRatesFragment fragment = new ExchangeRatesFragment(); fragment.setArguments(args); return fragment; } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mMetalId = getArguments().getString(METAL_ID); // Add this line in order for this fragment to handle menu events. setHasOptionsMenu(true); /* Attach a rotating ImageView to the refresh item as an ActionView */ inflater = (LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE); refreshImageView = (ImageView) inflater.inflate(R.layout.refresh_action_view, null); rotation = AnimationUtils.loadAnimation(getActivity(), R.anim.clockwise_refresh); rotation.setRepeatCount(Animation.INFINITE); } @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { inflater.inflate(R.menu.ratesfragment, menu); } @Override public boolean onOptionsItemSelected(MenuItem item) { int id = item.getItemId(); if (id == R.id.action_refresh) { refreshItem = item; if (Utility.isNetworkAvailable(getActivity())) { mPosition = RecyclerView.NO_POSITION; //mSwipeRefreshLayout.setRefreshing(true); refreshImageView.startAnimation(rotation); refreshItem.setActionView(refreshImageView); MetalsExchangeSyncAdapter.syncImmediately(getActivity(), true); } return true; } return super.onOptionsItemSelected(item); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_main, container, false); mSwipeRefreshLayout = (SwipeRefreshLayout) rootView.findViewById(R.id.activity_main_swipe_refresh_layout); // mSwipeRefreshLayout.setColorSchemeColors(R.color.primary_dark, R.color.primary_light, R.color.primary); mSwipeRefreshLayout.setColorSchemeColors(Color.RED, Color.GREEN, Color.BLUE, Color.CYAN); mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() { @Override public void onRefresh() { mPosition = RecyclerView.NO_POSITION; updateRates(); //mSwipeRefreshLayout.setRefreshing(false); } }); // Get a reference to the ListView, and attach this adapter to it. mRecyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerview_rates); // Set the layout manager mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity())); View emptyView = rootView.findViewById(R.id.recyclerview_rates_empty); mRecyclerView.setAdapter(mExchangeRatesAdapter); mRecyclerView.addItemDecoration(new DividerItemDecoration(getActivity(), LinearLayoutManager.VERTICAL)); // use this setting to improve performance if you know that changes // in content do not change the layout size of the RecyclerView mRecyclerView.setHasFixedSize(true); mExchangeRatesAdapter = new ExchangeRatesAdapter(getActivity(), mMetalId, new ExchangeRatesAdapter.ExchangeRatesAdapterOnClickHandler() { @Override public void onClick(Long date, ExchangeRatesAdapter.RatesAdapterViewHolder vh) { ((Callback) getActivity()).onItemSelected( MetalsContract.MetalsRateEntry.buildMetalRatesWithDate(mMetalId, date)); mPosition = vh.getAdapterPosition(); } @Override public void onRefreshCurrent() { if (Utility.isNetworkAvailable(getActivity())) { mPosition = RecyclerView.NO_POSITION; mSwipeRefreshLayout.setRefreshing(true); MetalsExchangeSyncAdapter.syncImmediately(getActivity(), true); } } }, emptyView); mRecyclerView.setAdapter(mExchangeRatesAdapter); // We'll call our MainActivity // mRecyclerView.setOnItemClickListener(new AdapterView.OnItemClickListener() { // // @Override // public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) { // // CursorAdapter returns a cursor at the correct position for getItem(), or null // // if it cannot seek to that position. // Cursor cursor = (Cursor) adapterView.getItemAtPosition(position); // if (cursor != null) { // ((Callback) getActivity()) // .onItemSelected(MetalsContract.MetalsRateEntry.buildMetalRatesWithDate( // mMetalId, cursor.getLong(COL_RATE_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 RecyclerView probably hasn't even been populated yet. Actually perform the // swapout in onLoadFinished. mPosition = savedInstanceState.getInt(SELECTED_KEY); } mExchangeRatesAdapter.setUseTodayLayout(!Utility.isTwoPanesView()); return rootView; } @Override public void onResume() { SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity()); sp.registerOnSharedPreferenceChangeListener(this); super.onResume(); getLoaderManager().restartLoader(RATES_LOADER, null, this); } @Override public void onPause() { SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity()); sp.unregisterOnSharedPreferenceChangeListener(this); super.onPause(); } @Override public void onActivityCreated(Bundle savedInstanceState) { getLoaderManager().initLoader(RATES_LOADER, null, this); super.onActivityCreated(savedInstanceState); } private void updateRates() { if (Utility.isNetworkAvailable(getActivity())) { MetalsExchangeSyncAdapter.syncImmediately(getActivity(), false); } else { mSwipeRefreshLayout.setRefreshing(false); } } @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 RecyclerView.NO_POSITION, // so check for that before storing. if (mPosition != RecyclerView.NO_POSITION) { outState.putInt(SELECTED_KEY, mPosition); } super.onSaveInstanceState(outState); } @Override public Loader<Cursor> onCreateLoader(int i, Bundle bundle) { // Sort order: Descending, by date. String sortOrder = MetalsContract.MetalsRateEntry.COLUMN_DATE + " DESC"; Uri ratesByMetalUri = MetalsContract.MetalsRateEntry.buildMetalsRateWithStartDate(mMetalId, System.currentTimeMillis()); return new CursorLoader(getActivity(), ratesByMetalUri, RATES_COLUMNS, null, null, sortOrder); } @Override public void onLoadFinished(Loader<Cursor> loader, Cursor data) { mExchangeRatesAdapter.swapCursor(data); if (mPosition != RecyclerView.NO_POSITION) { // If we don't need to restart the loader, and there's a desired position to restore // to, do so now. mRecyclerView.smoothScrollToPosition(mPosition); } updateEmptyView(); mSwipeRefreshLayout.setRefreshing(false); completeRefresh(); } public void completeRefresh() { if (refreshItem != null && refreshItem.getActionView() != null) { refreshItem.getActionView().clearAnimation(); refreshItem.setActionView(null); } } private void onCurrencyOrWeightChanged() { getLoaderManager().restartLoader(RATES_LOADER, null, this); } @Override public void onLoaderReset(Loader<Cursor> loader) { mExchangeRatesAdapter.swapCursor(null); } /* Updates the empty list view with contextually relevant information that the user can use to determine why they aren't seeing weather. */ private void updateEmptyView() { if (mExchangeRatesAdapter.getItemCount() == 0) { TextView tv = (TextView) getView().findViewById(R.id.recyclerview_rates_empty); if (null != tv) { // if cursor is empty, why? do we have an invalid location //String message = getActivity().getResources().getString(R.string.empty_rates_list); String message = ""; if (Utility.syncAllAvailableDataOfThisYear(getActivity())) {//on first launch --> no data message = getActivity().getResources().getString(R.string.empty_rates_list_startup); } @MetalsExchangeSyncAdapter.RatesStatus int location = Utility.getRatesStatus(getActivity()); switch (location) { case MetalsExchangeSyncAdapter.RATES_STATUS_SERVER_DOWN: message = getActivity().getResources().getString(R.string.empty_rates_list_server_down); break; case MetalsExchangeSyncAdapter.RATES_STATUS_SERVER_INVALID: message = getActivity().getResources().getString(R.string.empty_rates_list_server_error); break; default: if (!Utility.isNetworkAvailable(getActivity())) { message = getActivity().getResources().getString(R.string.empty_rates_list_no_network); } } tv.setText(message); } } } @Override public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) { if (key.equals(getString(R.string.pref_rates_status_key))) { updateEmptyView(); } else { onCurrencyOrWeightChanged(); } } }