package org.michenux.drodrolib.db; /* * Copyright (C) 2014 skyfish.jy@gmail.com * * 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. * */ import android.database.Cursor; import android.database.DataSetObserver; import android.support.v7.widget.RecyclerView; public abstract class CursorRecyclerViewAdapter<VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> { private Cursor mCursor; private boolean mDataValid; private int mRowIdColumn; private DataSetObserver mDataSetObserver; public CursorRecyclerViewAdapter(Cursor cursor) { mCursor = cursor; mDataValid = cursor != null; mRowIdColumn = mDataValid ? mCursor.getColumnIndex("_id") : -1; mDataSetObserver = new NotifyingDataSetObserver(); if (mCursor != null) { mCursor.registerDataSetObserver(mDataSetObserver); } } public Cursor getCursor() { return mCursor; } @Override public int getItemCount() { if (mDataValid && mCursor != null) { return mCursor.getCount(); } return 0; } @Override public long getItemId(int position) { if (mDataValid && mCursor != null && mCursor.moveToPosition(position)) { return mCursor.getLong(mRowIdColumn); } return 0; } @Override public void setHasStableIds(boolean hasStableIds) { super.setHasStableIds(true); } public abstract void onBindViewHolder(VH viewHolder, Cursor cursor); @Override public void onBindViewHolder(VH viewHolder, int position) { if (!mDataValid) { throw new IllegalStateException("this should only be called when the cursor is valid"); } if (!mCursor.moveToPosition(position)) { throw new IllegalStateException("couldn't move cursor to position " + position); } onBindViewHolder(viewHolder, mCursor); } /** * Change the underlying cursor to a new cursor. If there is an existing cursor it will be * closed. */ public void changeCursor(Cursor cursor) { Cursor old = swapCursor(cursor); if (old != null) { old.close(); } } /** * Swap in a new Cursor, returning the old Cursor. Unlike * {@link #changeCursor(Cursor)}, the returned old Cursor is <em>not</em> * closed. */ public Cursor swapCursor(Cursor newCursor) { if (newCursor == mCursor) { return null; } final Cursor oldCursor = mCursor; if (oldCursor != null && mDataSetObserver != null) { oldCursor.unregisterDataSetObserver(mDataSetObserver); } mCursor = newCursor; if (mCursor != null) { if (mDataSetObserver != null) { mCursor.registerDataSetObserver(mDataSetObserver); } mRowIdColumn = newCursor.getColumnIndexOrThrow("_id"); mDataValid = true; notifyDataSetChanged(); } else { mRowIdColumn = -1; mDataValid = false; notifyDataSetChanged(); //There is no notifyDataSetInvalidated() method in RecyclerView.Adapter } return oldCursor; } public void close() { if (mCursor != null) { mCursor.unregisterDataSetObserver(mDataSetObserver); mCursor = null; } } private class NotifyingDataSetObserver extends DataSetObserver { @Override public void onChanged() { super.onChanged(); mDataValid = true; notifyDataSetChanged(); } @Override public void onInvalidated() { super.onInvalidated(); mDataValid = false; notifyDataSetChanged(); //There is no notifyDataSetInvalidated() method in RecyclerView.Adapter } } }