Java tutorial
/* * Copyright 2012 GitHub Inc. * * 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.github.pockethub.ui; import android.app.Activity; import android.os.Bundle; import android.support.v4.app.LoaderManager.LoaderCallbacks; import android.support.v4.content.Loader; import android.support.v4.widget.SwipeRefreshLayout; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.animation.AnimationUtils; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.AdapterView.OnItemLongClickListener; import android.widget.ListAdapter; import android.widget.ListView; import android.widget.ProgressBar; import android.widget.TextView; import android.widget.Toast; import com.github.kevinsawicki.wishlist.SingleTypeAdapter; import com.github.kevinsawicki.wishlist.ViewUtils; import com.github.pockethub.R; import com.github.pockethub.ThrowableLoader; import com.github.pockethub.util.ToastUtils; import java.util.Collections; import java.util.List; /** * Base fragment for displaying a list of items that loads with a progress bar * visible * * @param <E> */ public abstract class ItemListFragment<E> extends DialogFragment implements LoaderCallbacks<List<E>>, SwipeRefreshLayout.OnRefreshListener { private static final String FORCE_REFRESH = "forceRefresh"; private SwipeRefreshLayout swipeLayout; /** * @param args * bundle passed to the loader by the LoaderManager * @return true if the bundle indicates a requested forced refresh of the * items */ protected static boolean isForceRefresh(Bundle args) { return args != null && args.getBoolean(FORCE_REFRESH, false); } /** * List items provided to {@link #onLoadFinished(Loader, List)} */ protected List<E> items = Collections.emptyList(); /** * List view */ protected ListView listView; /** * Empty view */ protected TextView emptyView; /** * Progress bar */ protected ProgressBar progressBar; /** * Is the list currently shown? */ protected boolean listShown; @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); if (!items.isEmpty()) setListShown(true, false); getLoaderManager().initLoader(0, null, this); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { return inflater.inflate(R.layout.item_list, container, false); } @Override public void onRefresh() { forceRefresh(); } /** * Detach from list view. */ @Override public void onDestroyView() { listShown = false; emptyView = null; progressBar = null; listView = null; super.onDestroyView(); } @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); swipeLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipe_item); swipeLayout.setOnRefreshListener(this); swipeLayout.setColorSchemeResources(R.color.pager_title_background_top_start, R.color.pager_title_background_end, R.color.text_link, R.color.pager_title_background_end); listView = (ListView) view.findViewById(android.R.id.list); listView.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { onListItemClick((ListView) parent, view, position, id); } }); listView.setOnItemLongClickListener(new OnItemLongClickListener() { @Override public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) { return onListItemLongClick((ListView) parent, view, position, id); } }); progressBar = (ProgressBar) view.findViewById(R.id.pb_loading); emptyView = (TextView) view.findViewById(android.R.id.empty); configureList(getActivity(), getListView()); } @Override public void onResume() { super.onResume(); refreshWithProgress(); } /** * Configure list after view has been created * * @param activity * @param listView */ protected void configureList(Activity activity, ListView listView) { listView.setAdapter(createAdapter()); } /** * Force a refresh of the items displayed ignoring any cached items */ protected void forceRefresh() { Bundle bundle = new Bundle(); bundle.putBoolean(FORCE_REFRESH, true); refresh(bundle); } /** * Refresh the fragment's list */ public void refresh() { refresh(null); } private void refresh(final Bundle args) { if (!isUsable()) return; getLoaderManager().restartLoader(0, args, this); } /** * Get error message to display for exception * * @param exception * @return string resource id */ protected abstract int getErrorMessage(Exception exception); public void onLoadFinished(Loader<List<E>> loader, List<E> items) { if (!isUsable()) return; swipeLayout.setRefreshing(false); Exception exception = getException(loader); if (exception != null) { showError(exception, getErrorMessage(exception)); showList(); return; } this.items = items; getListAdapter().getWrappedAdapter().setItems(items.toArray()); showList(); } /** * Create adapter to display items * * @return adapter */ protected HeaderFooterListAdapter<SingleTypeAdapter<E>> createAdapter() { SingleTypeAdapter<E> wrapped = createAdapter(items); return new HeaderFooterListAdapter<>(getListView(), wrapped); } /** * Create adapter to display items * * @param items * @return adapter */ protected abstract SingleTypeAdapter<E> createAdapter(final List<E> items); /** * Set the list to be shown */ protected void showList() { setListShown(true, isResumed()); } @Override public void onLoaderReset(Loader<List<E>> loader) { // Intentionally left blank } /** * Show exception in a {@link Toast} * * @param e * @param defaultMessage */ protected void showError(final Exception e, final int defaultMessage) { ToastUtils.show(getActivity(), e, defaultMessage); } /** * Get exception from loader if it provides one by being a * {@link ThrowableLoader} * * @param loader * @return exception or null if none provided */ protected Exception getException(final Loader<List<E>> loader) { if (loader instanceof ThrowableLoader) return ((ThrowableLoader<List<E>>) loader).clearException(); else return null; } /** * Refresh the list with the progress bar showing */ protected void refreshWithProgress() { items.clear(); setListShown(false); refresh(); } /** * Get {@link ListView} * * @return listView */ public ListView getListView() { return listView; } /** * Get list adapter * * @return list adapter */ @SuppressWarnings("unchecked") protected HeaderFooterListAdapter<SingleTypeAdapter<E>> getListAdapter() { if (listView != null) return (HeaderFooterListAdapter<SingleTypeAdapter<E>>) listView.getAdapter(); else return null; } /** * Notify the underlying adapter that the data set has changed * * @return this fragment */ protected ItemListFragment<E> notifyDataSetChanged() { HeaderFooterListAdapter<SingleTypeAdapter<E>> root = getListAdapter(); if (root != null) { SingleTypeAdapter<E> typeAdapter = root.getWrappedAdapter(); if (typeAdapter != null) typeAdapter.notifyDataSetChanged(); } return this; } /** * Set list adapter to use on list view * * @param adapter * @return this fragment */ protected ItemListFragment<E> setListAdapter(final ListAdapter adapter) { if (listView != null) listView.setAdapter(adapter); return this; } private ItemListFragment<E> fadeIn(final View view, final boolean animate) { if (view != null) if (animate) view.startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_in)); else view.clearAnimation(); return this; } private ItemListFragment<E> show(final View view) { ViewUtils.setGone(view, false); return this; } private ItemListFragment<E> hide(final View view) { ViewUtils.setGone(view, true); return this; } /** * Set list shown or progress bar show * * @param shown * @return this fragment */ public ItemListFragment<E> setListShown(final boolean shown) { return setListShown(shown, true); } /** * Set list shown or progress bar show * * @param shown * @param animate * @return this fragment */ public ItemListFragment<E> setListShown(final boolean shown, final boolean animate) { if (!isUsable()) return this; if (shown == listShown) { if (shown) // List has already been shown so hide/show the empty view with // no fade effect if (items.isEmpty()) hide(listView).show(emptyView); else hide(emptyView).show(listView); return this; } listShown = shown; if (shown) if (!items.isEmpty()) hide(progressBar).hide(emptyView).fadeIn(listView, animate).show(listView); else hide(progressBar).hide(listView).fadeIn(emptyView, animate).show(emptyView); else hide(listView).hide(emptyView).fadeIn(progressBar, animate).show(progressBar); return this; } /** * Set empty text on list fragment * * @param message * @return this fragment */ protected ItemListFragment<E> setEmptyText(final String message) { if (emptyView != null) emptyView.setText(message); return this; } /** * Set empty text on list fragment * * @param resId * @return this fragment */ protected ItemListFragment<E> setEmptyText(final int resId) { if (emptyView != null) emptyView.setText(resId); return this; } /** * Callback when a list view item is clicked * * @param l * @param v * @param position * @param id */ public void onListItemClick(ListView l, View v, int position, long id) { } /** * Callback when a list view item is clicked and held * * @param l * @param v * @param position * @param id * @return true if the callback consumed the long click, false otherwise */ public boolean onListItemLongClick(ListView l, View v, int position, long id) { return false; } }