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A custom Adapter for the new RecyclerView, behaving like the CursorAdapter class from previous ListView and alike. Now with Filters and updated doc.
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/* | |
* The MIT License (MIT) | |
* | |
* Copyright (c) 2014 Matthieu Harlé | |
* | |
* 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.ContentObserver; | |
import android.database.Cursor; | |
import android.database.DataSetObserver; | |
import android.os.Handler; | |
import android.support.v7.widget.RecyclerView; | |
import android.widget.Filter; | |
import android.widget.FilterQueryProvider; | |
import android.widget.Filterable; | |
/** | |
* Provide a {@link android.support.v7.widget.RecyclerView.Adapter} implementation with cursor | |
* support. | |
* | |
* Child classes only need to implement {@link #onCreateViewHolder(android.view.ViewGroup, int)} and | |
* {@link #onBindViewHolderCursor(android.support.v7.widget.RecyclerView.ViewHolder, android.database.Cursor)}. | |
* | |
* This class does not implement deprecated fields and methods from CursorAdapter! Incidentally, | |
* only {@link android.widget.CursorAdapter#FLAG_REGISTER_CONTENT_OBSERVER} is available, so the | |
* flag is implied, and only the Adapter behavior using this flag has been ported. | |
* | |
* @param <VH> {@inheritDoc} | |
* | |
* @see android.support.v7.widget.RecyclerView.Adapter | |
* @see android.widget.CursorAdapter | |
* @see android.widget.Filterable | |
* @see fr.shywim.tools.adapter.CursorFilter.CursorFilterClient | |
*/ | |
public abstract class CursorRecyclerAdapter<VH | |
extends android.support.v7.widget.RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> | |
implements Filterable, CursorFilter.CursorFilterClient { | |
private boolean mDataValid; | |
private int mRowIDColumn; | |
private Cursor mCursor; | |
private ChangeObserver mChangeObserver; | |
private DataSetObserver mDataSetObserver; | |
private CursorFilter mCursorFilter; | |
private FilterQueryProvider mFilterQueryProvider; | |
public CursorRecyclerAdapter( Cursor cursor) { | |
init(cursor); | |
} | |
void init(Cursor c) { | |
boolean cursorPresent = c != null; | |
mCursor = c; | |
mDataValid = cursorPresent; | |
mRowIDColumn = cursorPresent ? c.getColumnIndexOrThrow("_id") : -1; | |
mChangeObserver = new ChangeObserver(); | |
mDataSetObserver = new MyDataSetObserver(); | |
if (cursorPresent) { | |
if (mChangeObserver != null) c.registerContentObserver(mChangeObserver); | |
if (mDataSetObserver != null) c.registerDataSetObserver(mDataSetObserver); | |
} | |
} | |
/** | |
* This method will move the Cursor to the correct position and call | |
* {@link #onBindViewHolderCursor(android.support.v7.widget.RecyclerView.ViewHolder, | |
* android.database.Cursor)}. | |
* | |
* @param holder {@inheritDoc} | |
* @param i {@inheritDoc} | |
*/ | |
@Override | |
public void onBindViewHolder(VH holder, int i){ | |
if (!mDataValid) { | |
throw new IllegalStateException("this should only be called when the cursor is valid"); | |
} | |
if (!mCursor.moveToPosition(i)) { | |
throw new IllegalStateException("couldn't move cursor to position " + i); | |
} | |
onBindViewHolderCursor(holder, mCursor); | |
} | |
/** | |
* See {@link android.widget.CursorAdapter#bindView(android.view.View, android.content.Context, | |
* android.database.Cursor)}, | |
* {@link #onBindViewHolder(android.support.v7.widget.RecyclerView.ViewHolder, int)} | |
* | |
* @param holder View holder. | |
* @param cursor The cursor from which to get the data. The cursor is already | |
* moved to the correct position. | |
*/ | |
public abstract void onBindViewHolderCursor(VH holder, Cursor cursor); | |
@Override | |
public int getItemCount() { | |
if (mDataValid && mCursor != null) { | |
return mCursor.getCount(); | |
} else { | |
return 0; | |
} | |
} | |
/** | |
* @see android.widget.ListAdapter#getItemId(int) | |
*/ | |
@Override | |
public long getItemId(int position) { | |
if (mDataValid && mCursor != null) { | |
if (mCursor.moveToPosition(position)) { | |
return mCursor.getLong(mRowIDColumn); | |
} else { | |
return 0; | |
} | |
} else { | |
return 0; | |
} | |
} | |
public Cursor getCursor(){ | |
return mCursor; | |
} | |
/** | |
* 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; | |
if (oldCursor != null) { | |
if (mChangeObserver != null) oldCursor.unregisterContentObserver(mChangeObserver); | |
if (mDataSetObserver != null) oldCursor.unregisterDataSetObserver(mDataSetObserver); | |
} | |
mCursor = newCursor; | |
if (newCursor != null) { | |
if (mChangeObserver != null) newCursor.registerContentObserver(mChangeObserver); | |
if (mDataSetObserver != null) newCursor.registerDataSetObserver(mDataSetObserver); | |
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 | |
// notifyDataSetInvalidated(); | |
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(); | |
} | |
/** | |
* Runs a query with the specified constraint. This query is requested | |
* by the filter attached to this adapter. | |
* | |
* The query is provided by a | |
* {@link android.widget.FilterQueryProvider}. | |
* If no provider is specified, the current cursor is not filtered and returned. | |
* | |
* After this method returns the resulting cursor is passed to {@link #changeCursor(Cursor)} | |
* and the previous cursor is closed. | |
* | |
* This method is always executed on a background thread, not on the | |
* application's main thread (or UI thread.) | |
* | |
* Contract: when constraint is null or empty, the original results, | |
* prior to any filtering, must be returned. | |
* | |
* @param constraint the constraint with which the query must be filtered | |
* | |
* @return a Cursor representing the results of the new query | |
* | |
* @see #getFilter() | |
* @see #getFilterQueryProvider() | |
* @see #setFilterQueryProvider(android.widget.FilterQueryProvider) | |
*/ | |
public Cursor runQueryOnBackgroundThread(CharSequence constraint) { | |
if (mFilterQueryProvider != null) { | |
return mFilterQueryProvider.runQuery(constraint); | |
} | |
return mCursor; | |
} | |
public Filter getFilter() { | |
if (mCursorFilter == null) { | |
mCursorFilter = new CursorFilter(this); | |
} | |
return mCursorFilter; | |
} | |
/** | |
* Returns the query filter provider used for filtering. When the | |
* provider is null, no filtering occurs. | |
* | |
* @return the current filter query provider or null if it does not exist | |
* | |
* @see #setFilterQueryProvider(android.widget.FilterQueryProvider) | |
* @see #runQueryOnBackgroundThread(CharSequence) | |
*/ | |
public FilterQueryProvider getFilterQueryProvider() { | |
return mFilterQueryProvider; | |
} | |
/** | |
* Sets the query filter provider used to filter the current Cursor. | |
* The provider's | |
* {@link android.widget.FilterQueryProvider#runQuery(CharSequence)} | |
* method is invoked when filtering is requested by a client of | |
* this adapter. | |
* | |
* @param filterQueryProvider the filter query provider or null to remove it | |
* | |
* @see #getFilterQueryProvider() | |
* @see #runQueryOnBackgroundThread(CharSequence) | |
*/ | |
public void setFilterQueryProvider(FilterQueryProvider filterQueryProvider) { | |
mFilterQueryProvider = filterQueryProvider; | |
} | |
/** | |
* Called when the {@link ContentObserver} on the cursor receives a change notification. | |
* Can be implemented by sub-class. | |
* | |
* @see ContentObserver#onChange(boolean) | |
*/ | |
protected void onContentChanged() { | |
} | |
private class ChangeObserver extends ContentObserver { | |
public ChangeObserver() { | |
super(new Handler()); | |
} | |
@Override | |
public boolean deliverSelfNotifications() { | |
return true; | |
} | |
@Override | |
public void onChange(boolean selfChange) { | |
onContentChanged(); | |
} | |
} | |
private class MyDataSetObserver extends DataSetObserver { | |
@Override | |
public void onChanged() { | |
mDataValid = true; | |
notifyDataSetChanged(); | |
} | |
@Override | |
public void onInvalidated() { | |
mDataValid = false; | |
// notifyDataSetInvalidated(); | |
notifyItemRangeRemoved(0, getItemCount()); | |
} | |
} | |
/** | |
* <p>The CursorFilter delegates most of the work to the CursorAdapter. | |
* Subclasses should override these delegate methods to run the queries | |
* and convert the results into String that can be used by auto-completion | |
* widgets.</p> | |
*/ | |
} | |
class CursorFilter extends Filter { | |
CursorFilterClient mClient; | |
interface CursorFilterClient { | |
CharSequence convertToString(Cursor cursor); | |
Cursor runQueryOnBackgroundThread(CharSequence constraint); | |
Cursor getCursor(); | |
void changeCursor(Cursor cursor); | |
} | |
CursorFilter(CursorFilterClient client) { | |
mClient = client; | |
} | |
@Override | |
public CharSequence convertResultToString(Object resultValue) { | |
return mClient.convertToString((Cursor) resultValue); | |
} | |
@Override | |
protected FilterResults performFiltering(CharSequence constraint) { | |
Cursor cursor = mClient.runQueryOnBackgroundThread(constraint); | |
FilterResults results = new FilterResults(); | |
if (cursor != null) { | |
results.count = cursor.getCount(); | |
results.values = cursor; | |
} else { | |
results.count = 0; | |
results.values = null; | |
} | |
return results; | |
} | |
@Override | |
protected void publishResults(CharSequence constraint, FilterResults results) { | |
Cursor oldCursor = mClient.getCursor(); | |
if (results.values != null && results.values != oldCursor) { | |
mClient.changeCursor((Cursor) results.values); | |
} | |
} | |
} |
can u please provide me an example to work with filter and Loader manager with above shared gist.
Any example on how to use it with SQLite db file in assets
folder. I just want to retrieve it and display with RecyclerView
using above CursorLoader
.
Good class
how to call this addapter in main activity plz help me. i m beginner
Good afternoon. Tell me how to make a footer in your implementation of the adapter?
Hi, Everything works fine but when I enter text to filter RecyclerView each item in the view is gone. Any ideas why this is happening?
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Could you provide at least one usage example? Trying to convert a plain RecyclerView.Adapter to your implementation here, but I am having problems understanding how to use your onCreateViewHolder method to return something similar to - ViewHolder((LinearLayout)v). Not sure what I can reuse with your solution.
Updated: (Answering my own question)
Assuming you are using a subclass of this one:
In your override of onCreateViewHolder(), return an instance of a class that extends RecyclerView.ViewHolder.
In my case:
Just make sure your custom class extends RecyclerView.ViewHolder as such: