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.app.AppCompatActivity; import android.support.v7.view.ActionMode; import android.support.v7.widget.DefaultItemAnimator; import android.support.v7.widget.GridLayoutManager; import android.support.v7.widget.RecyclerView; import android.util.DisplayMetrics; 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 java.util.ArrayList; import java.util.Set; import ch.gianulli.flashcards.data.PreferenceModel; import ch.gianulli.flashcards.lists.BoardListAdapter; import ch.gianulli.flashcards.lists.BoardViewHolder; import ch.gianulli.flashcards.ui.MarginItemDecoration; import ch.gianulli.trelloapi.Board; import ch.gianulli.trelloapi.TrelloAPI; import ch.gianulli.trelloapi.TrelloNotAccessibleException; import ch.gianulli.trelloapi.TrelloNotAuthorizedException; public class BoardsFragment extends Fragment implements SwipeRefreshLayout.OnRefreshListener, BoardViewHolder.OnBoardSelectedListener, MarginItemDecoration.GridMetricsProvider { private static final String KEY_ACTIVE_PAGE = "active_page"; private TrelloAPI mTrelloApi; private PreferenceModel mPrefModel; private BoardsFragmentListener mListener; private BoardListAdapter mAdapter; private GridLayoutManager mLayoutManager; private RecyclerView mRecyclerView; private SwipeRefreshLayout mRefreshLayout; private View mProgressIndicator; private View mNoBoardsIndicator; private View mTrelloNotAccessibleIndicator; private AsyncTask mBoardLoader = null; private Page mActivePage; /** * Enables item selection */ private ActionMode.Callback mSelectItemsCallback = new ActionMode.Callback() { @Override public boolean onCreateActionMode(ActionMode mode, Menu menu) { if (mAdapter.areItemsSelectable()) { MenuInflater inflater = mode.getMenuInflater(); inflater.inflate(R.menu.context_boards, menu); return true; } return false; } @Override public boolean onPrepareActionMode(ActionMode mode, Menu menu) { return true; // Return false if nothing is done } @Override public boolean onActionItemClicked(final ActionMode mode, MenuItem item) { final ArrayList<Board> selectedBoards = mAdapter.getSelectedItems(); switch (item.getItemId()) { case R.id.action_hide: // Hide selected boards if (selectedBoards != null && selectedBoards.size() > 0) { String[] ids = new String[selectedBoards.size()]; for (int i = 0; i < selectedBoards.size(); ++i) { ids[i] = selectedBoards.get(i).getId(); } mPrefModel.addHiddenBoards(ids); mAdapter.removeBoards(selectedBoards); mode.finish(); // Action picked, so close the CAB return true; } break; } return false; } // Called when the user exits the action mode @Override public void onDestroyActionMode(ActionMode mode) { mAdapter.onFinishedActionMode(); } }; public BoardsFragment() { } public static BoardsFragment newInstance() { return new BoardsFragment(); } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mTrelloApi = new TrelloAPI(getActivity()); mPrefModel = new PreferenceModel(getActivity()); mAdapter = new BoardListAdapter((AppCompatActivity) getActivity(), this, mSelectItemsCallback); setRetainInstance(true); setHasOptionsMenu(true); } @Override public void onAttach(Activity activity) { super.onAttach(activity); if (!(activity instanceof BoardsFragmentListener)) { throw new IllegalArgumentException("Activity has to implement BoardsFragmentListener"); } else { mListener = (BoardsFragmentListener) activity; } } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View v = inflater.inflate(R.layout.fragment_boards, container, false); mProgressIndicator = v.findViewById(R.id.progress_indicator); mNoBoardsIndicator = v.findViewById(R.id.no_boards); 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 && savedInstanceState.containsKey(KEY_ACTIVE_PAGE)) { setActivePage(Page.values()[savedInstanceState.getInt(KEY_ACTIVE_PAGE)]); } // Set title getActivity().setTitle(R.string.title_activity_main); 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_boards, menu); } @Override public void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); if (mActivePage != null) { outState.putInt(KEY_ACTIVE_PAGE, mActivePage.ordinal()); } } @Override public void onPause() { if (mBoardLoader != null) { mBoardLoader.cancel(true); mBoardLoader = 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 (mBoardLoader != null) { mBoardLoader.cancel(true); mBoardLoader = null; } mBoardLoader = new AsyncTask<Void, Void, ArrayList<Board>>() { @Override protected void onPreExecute() { super.onPreExecute(); if (mAdapter.isEmpty()) { setActivePage(Page.PROGRESS); mRefreshLayout.setRefreshing(false); } else { setActivePage(Page.BOARD_LIST); mRefreshLayout.setRefreshing(true); } } @Override protected ArrayList<Board> doInBackground(Void... params) { try { // Get boards from Trello ArrayList<Board> result = Board.listAllBoards(mTrelloApi); // Remove hidden boards Set<String> hiddenBoards = mPrefModel.getHiddenBoards(); for (int i = result.size() - 1; i >= 0; --i) { String id = result.get(i).getId(); if (hiddenBoards.contains(id)) { result.remove(i); } } return result; } 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); } }); Log.d("test", "Trello not accessible: " + e.getMessage()); } return null; } @Override protected void onPostExecute(ArrayList<Board> boards) { mRefreshLayout.setRefreshing(false); mAdapter.setBoards(boards); if (boards != null) { if (mAdapter.isEmpty()) { setActivePage(Page.NO_BOARDS); } else { setActivePage(Page.BOARD_LIST); } } } }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR); } @Override public void onBoardSelected(Board board) { mListener.onBoardSelected(board); } private void setActivePage(Page page) { mActivePage = page; mProgressIndicator.setVisibility((page == Page.PROGRESS) ? View.VISIBLE : View.GONE); mNoBoardsIndicator.setVisibility((page == Page.NO_BOARDS) ? View.VISIBLE : View.GONE); mTrelloNotAccessibleIndicator.setVisibility((page == Page.NO_CONNECTION) ? View.VISIBLE : View.GONE); mRecyclerView.setVisibility((page == Page.BOARD_LIST) ? View.VISIBLE : View.GONE); } @Override public int getNumberOfGridColumns() { DisplayMetrics metrics = new DisplayMetrics(); getActivity().getWindowManager().getDefaultDisplay().getMetrics(metrics); int widthDp = (int) Math.ceil(metrics.widthPixels / metrics.density); return widthDp / 280; } public void setListener(BoardsFragmentListener listener) { mListener = listener; } private enum Page { BOARD_LIST, NO_CONNECTION, NO_BOARDS, PROGRESS } public interface BoardsFragmentListener { void onBoardSelected(Board board); } }