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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)
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/* | |
* 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(); | |
} | |
} |
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()'
I'm getting the same error as @newtsrock
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Can you please elaborate how to use your adapter with simple DB?