src/com.example.android.swiperefreshmultipleviews/SwipeRefreshMultipleViewsFragment.java

/*
 * Copyright 2016 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.swiperefreshmultipleviews;

import com.example.android.common.dummydata.Cheeses;
import com.example.android.common.logger.Log;

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.widget.SwipeRefreshLayout;
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.ArrayAdapter;
import android.widget.GridView;

import java.util.List;

/**
 * A sample which shows how to use {@link android.support.v4.widget.SwipeRefreshLayout} to add
 * the 'swipe-to-refresh' gesture to a layout with multiple children. In this sample,
 * SwipeRefreshLayout contains a scrollable {@link android.widget.GridView}, along with a
 * {@link android.widget.TextView} empty view.
 *
 * <p>To provide an accessible way to trigger the refresh, this app also provides a refresh
 * action item.
 *
 * <p>In this sample app, the refresh updates the GridView with a random set of new items.
 */
public class SwipeRefreshMultipleViewsFragment extends Fragment {

    private static final String LOG_TAG = SwipeRefreshMultipleViewsFragment.class.getSimpleName();

    private static final int LIST_ITEM_COUNT = 40;

    /**
     * The {@link MultiSwipeRefreshLayout} that detects swipe gestures and triggers callbacks in
     * the app.
     */
    private MultiSwipeRefreshLayout mSwipeRefreshLayout;

    /**
     * The {@link android.widget.GridView} that displays the content that should be refreshed.
     */
    private GridView mGridView;

    /**
     * The {@link android.widget.ListAdapter} used to populate the {@link android.widget.GridView}
     * defined in the previous statement.
     */
    private ArrayAdapter<String> mListAdapter;

    /**
     * The {@link View} which is displayed when the GridView is empty.
     */
    private View mEmptyView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Notify the system to allow an options menu for this fragment.
        setHasOptionsMenu(true);
    }

    // BEGIN_INCLUDE (inflate_view)
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_sample, container, false);

        mSwipeRefreshLayout = (MultiSwipeRefreshLayout) view.findViewById(R.id.swiperefresh);

        // BEGIN_INCLUDE (change_colors)
        // Set the color scheme of the SwipeRefreshLayout by providing 4 color resource ids
        mSwipeRefreshLayout.setColorSchemeResources(
                R.color.swipe_color_1, R.color.swipe_color_2,
                R.color.swipe_color_3, R.color.swipe_color_4);
        // END_INCLUDE (change_colors)

        mGridView = (GridView) view.findViewById(android.R.id.list);
        mEmptyView = view.findViewById(android.R.id.empty);
        return view;
    }
    // END_INCLUDE (inflate_view)

    // 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 GridView. Each item in the GridView
         * uses the system-defined simple_list_item_1 layout that contains one TextView. Initially
         */
        mListAdapter = new ArrayAdapter<>(
                getActivity(),
                android.R.layout.simple_list_item_1,
                android.R.id.text1);

        // Set the adapter between the GridView and its backing data.
        mGridView.setAdapter(mListAdapter);

        // Set the empty view so that it is displayed as needed
        mGridView.setEmptyView(mEmptyView);

        // BEGIN_INCLUDE (setup_swipeable_children)
        // Tell the MultiSwipeRefreshLayout which views are swipeable. In this case, the GridView
        // and empty view.
        mSwipeRefreshLayout.setSwipeableChildren(android.R.id.list, android.R.id.empty);
        // END_INCLUDE (setup_swipeable_children)

        // 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.
         */
        mSwipeRefreshLayout.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 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.
     */
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.menu_clear:
                Log.i(LOG_TAG, "Clear menu item selected");
                mListAdapter.clear();
                return true;

            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 (!mSwipeRefreshLayout.isRefreshing()) {
                    mSwipeRefreshLayout.setRefreshing(true);
                }

                // Start our refresh background task
                initiateRefresh();

                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 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
        mListAdapter.clear();
        for (String cheese : result) {
            mListAdapter.add(cheese);
        }

        // Stop the refreshing indicator
        mSwipeRefreshLayout.setRefreshing(false);
    }
    // END_INCLUDE (refresh_complete)

    /**
     * Placeholder {@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);
        }

    }
}