Java tutorial
/* * Copyright 2013 The GDG Frisbee 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 org.gdg.frisbee.android.fragment; import android.database.DataSetObserver; import android.os.Bundle; import android.os.Handler; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.animation.Animation; import android.view.animation.AnimationUtils; import android.widget.AdapterView; import android.widget.ListAdapter; import android.widget.ListView; import org.gdg.frisbee.android.R; import butterknife.ButterKnife; import butterknife.InjectView; /** * GDG Aachen * org.gdg.frisbee.android.app * <p/> * User: maui * Date: 23.04.13 * Time: 19:03 */ public class GdgListFragment extends Fragment { private static final String LOG_TAG = "GDG-ListFragment"; final private Handler mHandler = new Handler(); final private Runnable mRequestFocus = new Runnable() { public void run() { getListView().focusableViewAvailable(mList); } }; final private AdapterView.OnItemClickListener mOnClickListener = new AdapterView.OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View v, int position, long id) { onListItemClick(null, v, position, id); } }; ListAdapter mAdapter; AdapterView<ListAdapter> mList; @InjectView(R.id.empty) View mEmptyView; @InjectView(R.id.loading) View mProgressContainer; CharSequence mEmptyText; boolean mListShown; boolean mLoading; public GdgListFragment() { } /** * Provide default implementation to return a simple list view. Subclasses * can override to replace with their own layout. If doing so, the * returned view hierarchy <em>must</em> have a ListView whose id * is {@link android.R.id#list android.R.id.list} and can optionally * have a sibling view id {@link android.R.id#empty android.R.id.empty} * that is to be shown when the list is empty. * * <p>If you are overriding this method with your own custom content, * consider including the standard layout {@link android.R.layout#list_content} * in your layout file, so that you continue to retain all of the standard * behavior of ListFragment. In particular, this is currently the only * way to have the built-in indeterminant progress state be shown. */ @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View v = inflater.inflate(R.layout.fragment_list, null); ButterKnife.inject(this, v); return v; } /** * Attach to list view once the view hierarchy has been created. */ @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); ensureList(); } /** * Detach from list view. */ @Override public void onDestroyView() { mHandler.removeCallbacks(mRequestFocus); mList = null; mListShown = false; mEmptyView = mProgressContainer = null; super.onDestroyView(); } /** * This method will be called when an item in the list is selected. * Subclasses should override. Subclasses can call * getListView().getItemAtPosition(position) if they need to access the * data associated with the selected item. * * @param l The ListView where the click happened * @param v The view that was clicked within the ListView * @param position The position of the view in the list * @param id The row id of the item that was clicked */ public void onListItemClick(ListView l, View v, int position, long id) { } /** * Provide the cursor for the list view. */ public void setListAdapter(ListAdapter adapter) { boolean hadAdapter = mAdapter != null; mAdapter = adapter; if (mList != null) { mList.setAdapter(adapter); if (!mListShown && !hadAdapter) { // The list was hidden, and previously didn't have an // adapter. It is now time to show it. setListShown(true, getView().getWindowToken() != null); } } updateEmpty(); mAdapter.registerDataSetObserver(new DataSetObserver() { @Override public void onChanged() { super.onChanged(); updateEmpty(); } @Override public void onInvalidated() { super.onInvalidated(); updateEmpty(); } }); } private void updateEmpty() { if (!mLoading && getActivity() != null) { if (mAdapter == null || mAdapter.getCount() == 0) { setListShown(false, true); mEmptyView.startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_in)); mEmptyView.setVisibility(View.VISIBLE); } else { mEmptyView.startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_out)); mEmptyView.setVisibility(View.GONE); setListShown(true, true); } } } public void setIsLoading(boolean isLoading) { if (isLoading == mLoading || getActivity() == null) return; mLoading = isLoading; if (isLoading) { setListShown(false, true); mProgressContainer.startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_in)); mProgressContainer.setVisibility(View.VISIBLE); } else { Animation fadeOut = AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_out); fadeOut.setAnimationListener(new Animation.AnimationListener() { @Override public void onAnimationStart(Animation animation) { } @Override public void onAnimationEnd(Animation animation) { if (mProgressContainer != null) mProgressContainer.setVisibility(View.GONE); updateEmpty(); } @Override public void onAnimationRepeat(Animation animation) { } }); mProgressContainer.startAnimation(fadeOut); } } /** * Set the currently selected list item to the specified * position with the adapter's data * * @param position */ public void setSelection(int position) { ensureList(); mList.setSelection(position); } /** * Get the position of the currently selected list item. */ public int getSelectedItemPosition() { ensureList(); return mList.getSelectedItemPosition(); } /** * Get the cursor row ID of the currently selected list item. */ public long getSelectedItemId() { ensureList(); return mList.getSelectedItemId(); } /** * Get the activity's list view widget. */ public AdapterView<ListAdapter> getListView() { ensureList(); return mList; } /** * Control whether the list is being displayed. You can make it not * displayed if you are waiting for the initial data to show in it. During * this time an indeterminant progress indicator will be shown instead. * * <p>Applications do not normally need to use this themselves. The default * behavior of ListFragment is to start with the list not being shown, only * showing it once an adapter is given with {@link #setListAdapter(ListAdapter)}. * If the list at that point had not been shown, when it does get shown * it will be do without the user ever seeing the hidden state. * * @param shown If true, the list view is shown; if false, the progress * indicator. The initial value is true. */ public void setListShown(boolean shown) { setListShown(shown, true); } /** * Like {@link #setListShown(boolean)}, but no animation is used when * transitioning from the previous state. */ public void setListShownNoAnimation(boolean shown) { setListShown(shown, false); } /** * Control whether the list is being displayed. You can make it not * displayed if you are waiting for the initial data to show in it. During * this time an indeterminant progress indicator will be shown instead. * * @param shown If true, the list view is shown; if false, the progress * indicator. The initial value is true. * @param animate If true, an animation will be used to transition to the * new state. */ private void setListShown(boolean shown, boolean animate) { ensureList(); if (mProgressContainer == null) { throw new IllegalStateException("Can't be used with a custom content view"); } if (mListShown == shown) { return; } mListShown = shown; if (shown) { if (animate) { mList.startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_in)); } else { mList.clearAnimation(); } mList.setVisibility(View.VISIBLE); } else { if (animate) { mList.startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_out)); } else { mList.clearAnimation(); } mList.setVisibility(View.GONE); } } /** * Get the ListAdapter associated with this activity's ListView. */ public ListAdapter getListAdapter() { return mAdapter; } private void ensureList() { if (mList != null) { return; } View root = getView(); if (root == null) { throw new IllegalStateException("Content view not yet created"); } View rawList = root.findViewById(android.R.id.list); if (mEmptyView == null) { throw new RuntimeException("Your content must have a View whose id attribute is " + "'R.id.empty'"); } if (mProgressContainer == null) { throw new RuntimeException("Your content must have a View whose id attribute is " + "'R.id.loading'"); } mProgressContainer.setVisibility(View.GONE); if (rawList == null) { throw new RuntimeException("Your content must have a ListView whose id attribute is " + "'R.id.list'"); } if (!(rawList instanceof AdapterView)) { throw new RuntimeException( "Content has view with id attribute 'R.id.list' " + "that is not a ListView class"); } mList = (AdapterView<ListAdapter>) rawList; mListShown = true; mList.setOnItemClickListener(mOnClickListener); if (mAdapter != null) { ListAdapter adapter = mAdapter; mAdapter = null; setListAdapter(adapter); } else { // We are starting without an adapter, so assume we won't // have our data right away and start with the progress indicator. if (mProgressContainer != null) { setListShown(false, false); } } mHandler.post(mRequestFocus); } }