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.app4am.app4am; import android.app.Activity; import android.os.AsyncTask; import android.os.Bundle; import android.support.v4.widget.SwipeRefreshLayout; import android.util.Log; 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.ArrayAdapter; import android.widget.ListAdapter; import android.widget.ListView; import android.widget.Toast; import com.app4am.app4am.test.Cheeses; 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 com.app4am.app4am.SwipeRefreshListFragment} class. * <p/> * <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/> * <p>In this sample app, the refresh updates the ListView with a random set of new items. * <p/> * <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 LatestNewsListFragment extends SwipeRefreshListFragment { private static final String LOG_TAG = LatestNewsListFragment.class.getSimpleName(); private static final int LIST_ITEM_COUNT = 20; /** * 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/> * <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. */ boolean checkedState = false; private SwipeRefreshFragmentInterface mListener = null; private int mPosition; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Bundle args = getArguments(); if (args != null) { mPosition = args.getInt(SwipeRefreshFragmentInterface.FRAGMENT_POSITION); } // Notify the system to allow an options menu for this fragment. setHasOptionsMenu(true); } // BEGIN_INCLUDE (setup_refresh_menu_listener) // BEGIN_INCLUDE (setup_views) @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); if (savedInstanceState != null) { mPosition = savedInstanceState.getInt(SwipeRefreshFragmentInterface.FRAGMENT_POSITION); } // Change the colors displayed by the SwipeRefreshLayout by providing it with 4 // color resource ids setColorSchemeResources(R.color.color_scheme_1_1, R.color.color_scheme_1_2, R.color.color_scheme_1_3, R.color.color_scheme_1_4); // Set list view background color. view.setBackgroundResource(R.color.color_common_list_background); // List item divider and background color ListView listView = getListView(); listView.setDivider(getResources().getDrawable(R.drawable.common_list_divider)); listView.setDividerHeight((int) getResources().getDimension(R.dimen.common_list_divider_height)); listView.setBackgroundResource(R.color.color_common_list_background); listView.setCacheColorHint(0); // List selector listView.setSelector(R.drawable.list_view_selector); listView.setDrawSelectorOnTop(true); // Event handler listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { // TODO: Open topic information page (B01) ?! Log.d(LOG_TAG, "on click"); } }); listView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() { @Override public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) { // TODO: Open topic introduction page (B02) ?! Log.d(LOG_TAG, "on long click"); return false; } }); /** * 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(), R.layout.latest_news_list_item, R.id.textView, Cheeses.randomList(LIST_ITEM_COUNT)); // Set the adapter between the ListView and its backing data. setListAdapter(adapter); // BEGIN_INCLUDE (setup_refreshlistener) /** * Implement {@link android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener}. When users do the "swipe to * refresh" gesture, SwipeRefreshLayout invokes * {@link android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener#onRefresh onRefresh()}. In * {@link android.support.v4.widget.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. */ setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() { @Override public void onRefresh() { Log.i(LOG_TAG, "onRefresh called from SwipeRefreshLayout"); initiateRefresh(); } }); // END_INCLUDE (setup_refreshlistener) } // END_INCLUDE (setup_views) @Override public void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); outState.putInt(SwipeRefreshFragmentInterface.FRAGMENT_POSITION, mPosition); } @Override public void onAttach(Activity activity) { super.onAttach(activity); try { mListener = (SwipeRefreshFragmentInterface) getActivity(); } catch (ClassCastException e) { throw new ClassCastException("Activity must implement SwipeRefreshFragmentInterface."); } } @Override public void onDetach() { super.onDetach(); mListener = null; } @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { super.onCreateOptionsMenu(menu, inflater); // inflater.inflate(R.menu.main_menu, menu); } // END_INCLUDE (setup_refresh_menu_listener) // BEGIN_INCLUDE (initiate_refresh) @Override public boolean onOptionsItemSelected(MenuItem item) { int id = item.getItemId(); switch (id) { case R.id.action_search: Toast.makeText(getActivity(), "frag action_search", Toast.LENGTH_SHORT).show(); return true; case R.id.action_catalog: item.setChecked(true); checkedState = !checkedState; getActivity().supportInvalidateOptionsMenu(); // calls onPrepareOptionsMenu() Toast.makeText(getActivity(), "frag action_catalog", Toast.LENGTH_SHORT).show(); return true; } return super.onOptionsItemSelected(item); } // END_INCLUDE (initiate_refresh) // BEGIN_INCLUDE (refresh_complete) /** * 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 initiateRefresh() { Log.i(LOG_TAG, "initiateRefresh"); /** * Execute the background task, which uses {@link android.os.AsyncTask} to load the data. */ // new DummyBackgroundTask().execute(); mListener.onRefreshRequest(this); } /** * 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 try { ArrayAdapter<String> adapter = (ArrayAdapter<String>) getListAdapter(); adapter.clear(); for (String cheese : result) { adapter.add(cheese); } } catch (ClassCastException e) { Log.e(LOG_TAG, e.toString()); } // Stop the refreshing indicator setRefreshing(false); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { return super.onCreateView(inflater, container, savedInstanceState); } // END_INCLUDE (refresh_complete) @Override public void onPrepareOptionsMenu(Menu menu) { super.onPrepareOptionsMenu(menu); MenuItem item = menu.findItem(R.id.action_catalog); if (item != null) { boolean checked = item.isChecked(); Log.d("checked", "state: " + checked + ", internal checked: " + checkedState); item.setChecked(checkedState); } } /** * Dummy {@link android.os.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); } } }