Java tutorial
/* * Copyright 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.example.android.swiperefreshlistfragment; import android.graphics.Color; import android.graphics.drawable.ColorDrawable; import android.os.AsyncTask; import android.os.Bundle; import android.support.v4.widget.SwipeRefreshLayout; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.widget.ArrayAdapter; import com.android.volley.Cache; import com.android.volley.Request; import com.android.volley.Response; import com.android.volley.VolleyError; import com.android.volley.VolleyLog; import com.android.volley.toolbox.JsonObjectRequest; import com.example.android.common.dummydata.Cheeses; import com.example.android.common.logger.Log; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import java.io.UnsupportedEncodingException; import java.util.ArrayList; import java.util.List; /** * A sample which shows how to use {@link android.support.v4.widget.SwipeRefreshLayout} within a * {@link android.support.v4.app.ListFragment} to add the 'swipe-to-refresh' gesture to a * {@link android.widget.ListView}. This is provided through the provided re-usable * {@link SwipeRefreshListFragment} class. * * <p>To provide an accessible way to trigger the refresh, this app also provides a refresh * action item. This item should be displayed in the Action Bar's overflow item. * * <p>In this sample app, the refresh updates the ListView with a random set of new items. * * <p>This sample also provides the functionality to change the colors displayed in the * {@link android.support.v4.widget.SwipeRefreshLayout} through the options menu. This is meant to * showcase the use of color rather than being something that should be integrated into apps. */ public class SwipeRefreshListFragmentFragment extends SwipeRefreshListFragment { private static final String LOG_TAG = SwipeRefreshListFragmentFragment.class.getSimpleName(); private static final int LIST_ITEM_COUNT = 20; private FeedListAdapter mFeedListAdapter; private List<FeedItem> mFeedItems; private String URL_FEED = "http://api.androidhive.info/feed/feed.json"; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Notify the system to allow an options menu for this fragment. setHasOptionsMenu(true); } // BEGIN_INCLUDE (setup_views) @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); /** * Create an ArrayAdapter to contain the data for the ListView. Each item in the ListView * uses the system-defined simple_list_item_1 layout that contains one TextView. */ // ListAdapter adapter = new ArrayAdapter<String>( // getActivity(), // android.R.layout.simple_list_item_1, // android.R.id.text1, // Cheeses.randomList(LIST_ITEM_COUNT)); mFeedItems = new ArrayList<FeedItem>(); mFeedListAdapter = new FeedListAdapter(getActivity(), mFeedItems); // Set the adapter between the ListView and its backing data. setListAdapter(mFeedListAdapter); // BEGIN_INCLUDE (setup_refreshlistener) /** * Implement {@link SwipeRefreshLayout.OnRefreshListener}. When users do the "swipe to * refresh" gesture, SwipeRefreshLayout invokes * {@link SwipeRefreshLayout.OnRefreshListener#onRefresh onRefresh()}. In * {@link SwipeRefreshLayout.OnRefreshListener#onRefresh onRefresh()}, call a method that * refreshes the content. Call the same method in response to the Refresh action from the * action bar. */ // These two lines not needed, // just to get the look of facebook (changing background color & hiding the icon) getActivity().getActionBar().setBackgroundDrawable(new ColorDrawable(Color.parseColor("#3b5998"))); getActivity().getActionBar() .setIcon(new ColorDrawable(getResources().getColor(android.R.color.transparent))); setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() { @Override public void onRefresh() { Log.i(LOG_TAG, "onRefresh called from SwipeRefreshLayout"); doRequest(); // initiateRefresh(); } }); // END_INCLUDE (setup_refreshlistener) } // END_INCLUDE (setup_views) @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { inflater.inflate(R.menu.main_menu, menu); } // BEGIN_INCLUDE (setup_refresh_menu_listener) /** * Respond to the user's selection of the Refresh action item. Start the SwipeRefreshLayout * progress bar, then initiate the background task that refreshes the content. * * <p>A color scheme menu item used for demonstrating the use of SwipeRefreshLayout's color * scheme functionality. This kind of menu item should not be incorporated into your app, * it just to demonstrate the use of color. Instead you should choose a color scheme based * off of your application's branding. */ @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.menu_refresh: Log.i(LOG_TAG, "Refresh menu item selected"); // We make sure that the SwipeRefreshLayout is displaying it's refreshing indicator if (!isRefreshing()) { setRefreshing(true); } // Start our refresh background task // initiateRefresh(); return true; case R.id.menu_color_scheme_1: Log.i(LOG_TAG, "setColorScheme #1"); item.setChecked(true); // Change the colors displayed by the SwipeRefreshLayout by providing it with 4 // color resource ids setColorScheme(R.color.color_scheme_1_1, R.color.color_scheme_1_2, R.color.color_scheme_1_3, R.color.color_scheme_1_4); return true; case R.id.menu_color_scheme_2: Log.i(LOG_TAG, "setColorScheme #2"); item.setChecked(true); // Change the colors displayed by the SwipeRefreshLayout by providing it with 4 // color resource ids setColorScheme(R.color.color_scheme_2_1, R.color.color_scheme_2_2, R.color.color_scheme_2_3, R.color.color_scheme_2_4); return true; case R.id.menu_color_scheme_3: Log.i(LOG_TAG, "setColorScheme #3"); item.setChecked(true); // Change the colors displayed by the SwipeRefreshLayout by providing it with 4 // color resource ids setColorScheme(R.color.color_scheme_3_1, R.color.color_scheme_3_2, R.color.color_scheme_3_3, R.color.color_scheme_3_4); return true; } return super.onOptionsItemSelected(item); } // END_INCLUDE (setup_refresh_menu_listener) // BEGIN_INCLUDE (initiate_refresh) /** * By abstracting the refresh process to a single method, the app allows both the * SwipeGestureLayout onRefresh() method and the Refresh action item to refresh the content. */ private void doRequest() { Log.i(LOG_TAG, "doRequest"); // We first check for cached request Cache cache = AppController.getInstance().getRequestQueue().getCache(); Cache.Entry entry = cache.get(URL_FEED); if (entry != null) { // fetch the data from cache try { String data = new String(entry.data, "UTF-8"); try { setRefreshing(false); parseJsonFeed(new JSONObject(data)); } catch (JSONException e) { e.printStackTrace(); } } catch (UnsupportedEncodingException e) { e.printStackTrace(); } } else { // making fresh volley request and getting json JsonObjectRequest jsonReq = new JsonObjectRequest(Request.Method.GET, URL_FEED, null, new Response.Listener<JSONObject>() { @Override public void onResponse(JSONObject response) { VolleyLog.d(LOG_TAG, "Response: " + response.toString()); setRefreshing(false); if (response != null) { parseJsonFeed(response); } } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { VolleyLog.d(LOG_TAG, "Error: " + error.getMessage()); setRefreshing(false); } }); // Adding request to volley request queue AppController.getInstance().addToRequestQueue(jsonReq); } } /** * Parsing json reponse and passing the data to feed view list adapter * */ private void parseJsonFeed(JSONObject response) { try { JSONArray feedArray = response.getJSONArray("feed"); for (int i = 0; i < feedArray.length(); i++) { JSONObject feedObj = (JSONObject) feedArray.get(i); FeedItem item = new FeedItem(); item.setId(feedObj.getInt("id")); item.setName(feedObj.getString("name")); // Image might be null sometimes String image = feedObj.isNull("image") ? null : feedObj.getString("image"); item.setImge(image); item.setStatus(feedObj.getString("status")); item.setProfilePic(feedObj.getString("profilePic")); item.setTimeStamp(feedObj.getString("timeStamp")); // url might be null sometimes String feedUrl = feedObj.isNull("url") ? null : feedObj.getString("url"); item.setUrl(feedUrl); mFeedItems.add(item); } // notify data changes to list adapater mFeedListAdapter.notifyDataSetChanged(); } catch (JSONException e) { e.printStackTrace(); } } private void initiateRefresh() { Log.i(LOG_TAG, "initiateRefresh"); /** * Execute the background task, which uses {@link android.os.AsyncTask} to load the data. */ new DummyBackgroundTask().execute(); } // END_INCLUDE (initiate_refresh) // BEGIN_INCLUDE (refresh_complete) /** * When the AsyncTask finishes, it calls onRefreshComplete(), which updates the data in the * ListAdapter and turns off the progress bar. */ private void onRefreshComplete(List<String> result) { Log.i(LOG_TAG, "onRefreshComplete"); // Remove all items from the ListAdapter, and then replace them with the new items ArrayAdapter<String> adapter = (ArrayAdapter<String>) getListAdapter(); adapter.clear(); for (String cheese : result) { adapter.add(cheese); } // Stop the refreshing indicator setRefreshing(false); } // END_INCLUDE (refresh_complete) /** * Dummy {@link AsyncTask} which simulates a long running task to fetch new cheeses. */ private class DummyBackgroundTask extends AsyncTask<Void, Void, List<String>> { static final int TASK_DURATION = 3 * 1000; // 3 seconds @Override protected List<String> doInBackground(Void... params) { // Sleep for a small amount of time to simulate a background-task try { Thread.sleep(TASK_DURATION); } catch (InterruptedException e) { e.printStackTrace(); } // Return a new random list of cheeses return Cheeses.randomList(LIST_ITEM_COUNT); } @Override protected void onPostExecute(List<String> result) { super.onPostExecute(result); // Tell the Fragment that the refresh has completed onRefreshComplete(result); } } }