Java tutorial
/* * Copyright (C) 2013 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 org.sufficientlysecure.keychain.ui.base; import android.content.Context; import android.os.Bundle; import android.os.Handler; import android.support.v4.app.Fragment; import android.support.v7.widget.RecyclerView; import android.view.Gravity; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.animation.AnimationUtils; import android.widget.FrameLayout; import android.widget.LinearLayout; import android.widget.ProgressBar; import android.widget.TextView; import org.sufficientlysecure.keychain.Constants; import org.sufficientlysecure.keychain.ui.util.FormattingUtils; import org.sufficientlysecure.keychain.util.Log; /* * Implementation of taken from the sourcecode of * android.support.v4.app.ListFragment from the * Android Open Source Project and changed to use * RecyclerView instead of ListView. */ public class RecyclerFragment<A extends RecyclerView.Adapter> extends Fragment { protected static final int INTERNAL_LIST_VIEW_ID = android.R.id.list; protected static final int INTERNAL_EMPTY_VIEW_ID = android.R.id.empty; protected static final int INTERNAL_LIST_CONTAINER_ID = android.R.id.widget_frame; protected static final int INTERNAL_PROGRESS_CONTAINER_ID = android.R.id.progress; private final Handler handler = new Handler(); private final Runnable requestFocus = new Runnable() { @Override public void run() { listView.focusableViewAvailable(listView); } }; private boolean observerRegistered = false; private final RecyclerView.AdapterDataObserver dataObserver = new RecyclerView.AdapterDataObserver() { @Override public void onChanged() { super.onChanged(); checkDataSet(); } @Override public void onItemRangeInserted(int positionStart, int itemCount) { super.onItemRangeInserted(positionStart, itemCount); checkDataSet(); } @Override public void onItemRangeRemoved(int positionStart, int itemCount) { super.onItemRangeRemoved(positionStart, itemCount); checkDataSet(); } }; private final RecyclerView.OnScrollListener scrollListener = new RecyclerView.OnScrollListener() { @Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) { RecyclerFragment.this.onScrolled(dx, dy); } @Override public void onScrollStateChanged(RecyclerView recyclerView, int newState) { RecyclerFragment.this.onScrollStateChanged(newState); } }; private A adapter; private RecyclerView.LayoutManager layoutManager; private RecyclerView listView; private View emptyView; private View progressContainer; private View listContainer; private boolean listShown; public RecyclerFragment() { super(); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) { final Context context = getContext(); FrameLayout root = new FrameLayout(context); LinearLayout progressContainer = new LinearLayout(context); progressContainer.setId(INTERNAL_PROGRESS_CONTAINER_ID); progressContainer.setOrientation(LinearLayout.VERTICAL); progressContainer.setGravity(Gravity.CENTER); progressContainer.setVisibility(View.GONE); ProgressBar progressBar = new ProgressBar(context, null, android.R.attr.progressBarStyleLarge); progressContainer.addView(progressBar, new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT)); root.addView(progressContainer, new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); FrameLayout listContainer = new FrameLayout(context); listContainer.setId(INTERNAL_LIST_CONTAINER_ID); TextView textView = new TextView(context); textView.setId(INTERNAL_EMPTY_VIEW_ID); textView.setGravity(Gravity.CENTER); listContainer.addView(textView, new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); RecyclerView listView = new RecyclerView(context); listView.setId(INTERNAL_LIST_VIEW_ID); int padding = FormattingUtils.dpToPx(context, 8); listView.setPadding(padding, 0, padding, 0); listView.setClipToPadding(false); listContainer.addView(listView, new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); root.addView(listContainer, new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); root.setLayoutParams(new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); return root; } @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); ensureList(); } @Override public void onDestroyView() { handler.removeCallbacks(requestFocus); listView.setLayoutManager(null); listView.removeOnScrollListener(scrollListener); listView = null; listShown = false; listContainer = null; layoutManager = null; emptyView = null; progressContainer = null; super.onDestroyView(); } @Override public void onDestroy() { //setAdapter(null); super.onDestroy(); } public Handler getHandler() { return handler; } public void onScrollStateChanged(int state) { // empty body } public void onScrolled(int dx, int dy) { // empty body } public void setAdapter(A adapter) { unregisterObserver(); boolean hadAdapter = this.adapter != null; this.adapter = adapter; registerObserver(); if (listView != null) { listView.setAdapter(adapter); if (!listShown && !hadAdapter) { if (getView() != null) setListShown(true, getView().getWindowToken() != null); } } } public void setLayoutManager(RecyclerView.LayoutManager manager) { if (!manager.isAttachedToWindow()) { layoutManager = manager; if (listView != null) { listView.setLayoutManager(manager); } } } public int getItemCount() { if (adapter != null) return adapter.getItemCount(); else return 0; } public long getItemId(int position) { if (adapter != null) return adapter.getItemId(position); else return View.NO_ID; } public RecyclerView getRecyclerView() { ensureList(); return listView; } public RecyclerView.LayoutManager getLayoutManager() { ensureList(); return layoutManager; } private void registerObserver() { if (!observerRegistered && adapter != null) { adapter.registerAdapterDataObserver(dataObserver); observerRegistered = true; } } private void unregisterObserver() { if (observerRegistered && adapter != null) { adapter.unregisterAdapterDataObserver(dataObserver); observerRegistered = false; } } private void checkDataSet() { boolean empty = treatAsEmpty(getItemCount()); Log.d("RecyclerFragment", "Dataset change detected! Count: " + getItemCount() + ", Empty: " + empty); if (emptyView != null) { emptyView.setVisibility(empty ? View.VISIBLE : View.GONE); } } /** * Set whether the data set of the recycler view should be treated as empty. * This is useful e.g. if you have an empty padding row and therefore the item * count is always greater than 0. * * @param itemCount the number of items in the data set. * @return Whether to treat this as an empty set of data */ protected boolean treatAsEmpty(int itemCount) { return itemCount < 1; } /** * Set whether the recycler view should have a fixed size or not */ protected boolean isFixedSize() { return true; } public void hideList(boolean animated) { setListShown(false, animated); } public void showList(boolean animated) { setListShown(true, animated); } public void setEmptyText(String text) { ensureList(); if (emptyView instanceof TextView) { ((TextView) emptyView).setText(text); } else { Log.e(Constants.TAG, "Cannot set empty text on a view that is null" + "or not an instance of android.view.View!"); } } private void setListShown(boolean shown, boolean animated) { ensureList(); if (progressContainer == null) throw new IllegalStateException("Can't be used with a custom content view"); if (listShown == shown) return; listShown = shown; if (shown) { if (animated) { progressContainer .startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_out)); listContainer.startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_in)); } else { progressContainer.clearAnimation(); listContainer.clearAnimation(); } progressContainer.setVisibility(View.GONE); listContainer.setVisibility(View.VISIBLE); } else { if (animated) { progressContainer .startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_in)); listContainer.startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_out)); } else { progressContainer.clearAnimation(); listContainer.clearAnimation(); } progressContainer.setVisibility(View.VISIBLE); listContainer.setVisibility(View.GONE); } } public A getAdapter() { return adapter; } @SuppressWarnings("unchecked") private void ensureList() { if (listView != null) { return; } View root = getView(); if (root == null) { throw new IllegalStateException("Content view not yet created"); } if (root instanceof RecyclerView) { listView = (RecyclerView) root; } else { emptyView = root.findViewById(INTERNAL_EMPTY_VIEW_ID); if (emptyView != null) { emptyView.setVisibility(View.GONE); } progressContainer = root.findViewById(INTERNAL_PROGRESS_CONTAINER_ID); listContainer = root.findViewById(INTERNAL_LIST_CONTAINER_ID); View rawListView = root.findViewById(INTERNAL_LIST_VIEW_ID); if (!(rawListView instanceof RecyclerView)) { if (rawListView == null) { throw new RuntimeException( "Your content must have a RecyclerView whose id attribute is " + "'android.R.id.list'"); } throw new RuntimeException( "Content has view with id attribute 'android.R.id.list' " + "that is not a ListView class"); } listView = (RecyclerView) rawListView; } if (layoutManager != null) { RecyclerView.LayoutManager manager = layoutManager; this.layoutManager = null; setLayoutManager(manager); } listShown = true; listView.setHasFixedSize(isFixedSize()); listView.addOnScrollListener(scrollListener); if (this.adapter != null) { A adapter = this.adapter; this.adapter = null; setAdapter(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 (progressContainer != null) { setListShown(false, false); } } handler.post(requestFocus); } }