Java tutorial
/* * Copyright 2015 Gian Ulli * * 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 ch.gianulli.flashcards; import android.app.Activity; import android.content.Intent; import android.os.AsyncTask; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.widget.SwipeRefreshLayout; import android.support.v7.widget.DefaultItemAnimator; import android.support.v7.widget.GridLayoutManager; import android.support.v7.widget.RecyclerView; 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 java.util.ArrayList; import ch.gianulli.flashcards.lists.ListListAdapter; import ch.gianulli.flashcards.lists.ListViewHolder; import ch.gianulli.flashcards.ui.MarginItemDecoration; import ch.gianulli.trelloapi.Board; import ch.gianulli.trelloapi.TrelloAPI; import ch.gianulli.trelloapi.TrelloList; import ch.gianulli.trelloapi.TrelloNotAccessibleException; import ch.gianulli.trelloapi.TrelloNotAuthorizedException; public class ListsFragment extends Fragment implements SwipeRefreshLayout.OnRefreshListener, ListViewHolder.OnListSelectedListener, MarginItemDecoration.GridMetricsProvider { private static final String KEY_ACTIVE_PAGE = "active_page"; private static final String KEY_BOARD = "board"; private TrelloAPI mTrelloApi; private ListsFragmentListener mListener; private ListListAdapter mAdapter; private GridLayoutManager mLayoutManager; private RecyclerView mRecyclerView; private SwipeRefreshLayout mRefreshLayout; private View mProgressIndicator; private View mNoListsIndicator; private View mTrelloNotAccessibleIndicator; private AsyncTask mListLoader = null; private Page mActivePage; private Board mBoard; public ListsFragment() { } public static ListsFragment newInstance(Board board) { ListsFragment result = new ListsFragment(); Bundle args = new Bundle(); args.putParcelable(KEY_BOARD, board); result.setArguments(args); return result; } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mTrelloApi = new TrelloAPI(getActivity()); mAdapter = new ListListAdapter(this); mBoard = getArguments().getParcelable(KEY_BOARD); setRetainInstance(true); setHasOptionsMenu(true); } @Override public void onAttach(Activity activity) { super.onAttach(activity); if (!(activity instanceof ListsFragmentListener)) { throw new IllegalArgumentException("Activity has to implement BoardsFragmentListener"); } else { mListener = (ListsFragmentListener) activity; } } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View v = inflater.inflate(R.layout.fragment_lists, container, false); mProgressIndicator = v.findViewById(R.id.progress_indicator); mNoListsIndicator = v.findViewById(R.id.no_lists); mTrelloNotAccessibleIndicator = v.findViewById(R.id.trello_not_accessible); mRefreshLayout = (SwipeRefreshLayout) v.findViewById(R.id.refresh_layout); mRefreshLayout.setColorSchemeResources(R.color.color1, R.color.color2, R.color.color3); mRefreshLayout.setOnRefreshListener(this); mRecyclerView = (RecyclerView) v.findViewById(R.id.recycler_view); mRecyclerView.setItemAnimator(new DefaultItemAnimator()); mLayoutManager = new GridLayoutManager(getActivity(), getNumberOfGridColumns()); mRecyclerView.addItemDecoration(new MarginItemDecoration(getActivity(), 16, this)); mRecyclerView.setLayoutManager(mLayoutManager); mRecyclerView.setAdapter(mAdapter); mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() { @Override public void onScrollStateChanged(RecyclerView recyclerView, int newState) { super.onScrollStateChanged(recyclerView, newState); } @Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) { mRefreshLayout.setEnabled( mAdapter.isEmpty() || mLayoutManager.findFirstCompletelyVisibleItemPosition() == 0); } }); // Restore state if (savedInstanceState != null) { setActivePage(Page.values()[savedInstanceState.getInt(KEY_ACTIVE_PAGE)]); } // Set title getActivity().setTitle(mBoard.getName()); return v; } @Override public void onResume() { super.onResume(); onRefresh(); } @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { super.onCreateOptionsMenu(menu, inflater); inflater.inflate(R.menu.menu_lists, menu); } @Override public void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); outState.putInt(KEY_ACTIVE_PAGE, mActivePage.ordinal()); } @Override public void onPause() { if (mListLoader != null) { mListLoader.cancel(true); mListLoader = null; } // This hack solves a nasty bug that happens when switching fragments during refresh if (mRefreshLayout != null) { mRefreshLayout.setRefreshing(false); mRefreshLayout.destroyDrawingCache(); mRefreshLayout.clearAnimation(); } super.onPause(); } @Override public boolean onOptionsItemSelected(MenuItem item) { int id = item.getItemId(); switch (id) { case R.id.action_refresh: onRefresh(); break; case R.id.action_settings: Intent intent = new Intent(getActivity(), SettingsActivity.class); startActivity(intent); break; } return super.onOptionsItemSelected(item); } @Override public void onRefresh() { if (mListLoader != null) { mListLoader.cancel(true); mListLoader = null; } mListLoader = new AsyncTask<Void, Void, ArrayList<TrelloList>>() { @Override protected void onPreExecute() { super.onPreExecute(); if (mAdapter.isEmpty()) { setActivePage(Page.PROGRESS); mRefreshLayout.setRefreshing(false); } else { setActivePage(Page.LIST_LIST); mRefreshLayout.setRefreshing(true); } } @Override protected ArrayList<TrelloList> doInBackground(Void... params) { try { return mBoard.getAllLists(mTrelloApi); } catch (TrelloNotAuthorizedException e) { getActivity().runOnUiThread(new Runnable() { @Override public void run() { mTrelloApi.requestAuthorization(getActivity().getSupportFragmentManager()); } }); } catch (TrelloNotAccessibleException e) { getActivity().runOnUiThread(new Runnable() { @Override public void run() { setActivePage(Page.NO_CONNECTION); } }); } return null; } @Override protected void onPostExecute(ArrayList<TrelloList> lists) { mRefreshLayout.setRefreshing(false); mAdapter.setLists(lists); if (lists != null) { if (mAdapter.isEmpty()) { setActivePage(Page.NO_BOARDS); } else { setActivePage(Page.LIST_LIST); } } } }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR); } @Override public void onListSelected(TrelloList list) { mListener.onListSelected(list); } private void setActivePage(Page page) { mActivePage = page; mProgressIndicator.setVisibility((page == Page.PROGRESS) ? View.VISIBLE : View.GONE); mNoListsIndicator.setVisibility((page == Page.NO_BOARDS) ? View.VISIBLE : View.GONE); mTrelloNotAccessibleIndicator.setVisibility((page == Page.NO_CONNECTION) ? View.VISIBLE : View.GONE); mRecyclerView.setVisibility((page == Page.LIST_LIST) ? View.VISIBLE : View.GONE); } @Override public int getNumberOfGridColumns() { return 1; } public void setListener(ListsFragmentListener listener) { mListener = listener; } private enum Page { LIST_LIST, NO_CONNECTION, NO_BOARDS, PROGRESS } public interface ListsFragmentListener { void onListSelected(TrelloList list); } }