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A simple implementation of CursorAdapter for the new RecyclerView. It is designed to work with CursorLoaders and do not register any content observer (which can cause leaks if not handled properly)
/*
* The MIT License (MIT)
*
* Copyright (c) 2015 ARNAUD FRUGIER
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
import android.database.Cursor;
import android.support.v7.widget.RecyclerView;
public abstract class CursorRecyclerAdapter<VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> {
protected boolean mDataValid;
protected Cursor mCursor;
protected int mRowIDColumn;
public CursorRecyclerAdapter(Cursor c) {
init(c);
}
void init(Cursor c) {
boolean cursorPresent = c != null;
mCursor = c;
mDataValid = cursorPresent;
mRowIDColumn = cursorPresent ? c.getColumnIndexOrThrow("_id") : -1;
setHasStableIds(true);
}
@Override
public final void onBindViewHolder (VH holder, 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(holder, mCursor);
}
public abstract void onBindViewHolder(VH holder, Cursor cursor);
public Cursor getCursor() {
return mCursor;
}
@Override
public int getItemCount () {
if (mDataValid && mCursor != null) {
return mCursor.getCount();
} else {
return 0;
}
}
@Override
public long getItemId (int position) {
if(hasStableIds() && mDataValid && mCursor != null){
if (mCursor.moveToPosition(position)) {
return mCursor.getLong(mRowIDColumn);
} else {
return RecyclerView.NO_ID;
}
} else {
return RecyclerView.NO_ID;
}
}
/**
* Change the underlying cursor to a new cursor. If there is an existing cursor it will be
* closed.
*
* @param cursor The new cursor to be used
*/
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.
*
* @param newCursor The new cursor to be used.
* @return Returns the previously set Cursor, or null if there wasa not one.
* If the given new Cursor is the same instance is the previously set
* Cursor, null is also returned.
*/
public Cursor swapCursor(Cursor newCursor) {
if (newCursor == mCursor) {
return null;
}
Cursor oldCursor = mCursor;
mCursor = newCursor;
if (newCursor != null) {
mRowIDColumn = newCursor.getColumnIndexOrThrow("_id");
mDataValid = true;
// notify the observers about the new cursor
notifyDataSetChanged();
} else {
mRowIDColumn = -1;
mDataValid = false;
// notify the observers about the lack of a data set
notifyItemRangeRemoved(0, getItemCount());
}
return oldCursor;
}
/**
* <p>Converts the cursor into a CharSequence. Subclasses should override this
* method to convert their results. The default implementation returns an
* empty String for null values or the default String representation of
* the value.</p>
*
* @param cursor the cursor to convert to a CharSequence
* @return a CharSequence representing the value
*/
public CharSequence convertToString(Cursor cursor) {
return cursor == null ? "" : cursor.toString();
}
}
@Sprintzin

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Sprintzin commented Oct 23, 2015

Can you please elaborate how to use your adapter with simple DB?

@andrewfluck

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andrewfluck commented Jul 14, 2016

How do you use it??? I get this error: java.lang.NullPointerException: Attempt to invoke virtual method 'android.database.Cursor io.github.newtsrock.record.adapters.AlbumAdapter.getCursor()'

@brunopugliese

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brunopugliese commented Jan 13, 2017

I'm getting the same error as @Newtsrock

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