Created
January 8, 2016 17:05
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RecyclerView that wraps a Cursor.
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package com.cotap.android.adapters; | |
import android.content.Context; | |
import android.database.ContentObserver; | |
import android.database.Cursor; | |
import android.database.DataSetObserver; | |
import android.os.Handler; | |
import android.support.v7.widget.RecyclerView; | |
/** | |
* A milange of https://gist.github.com/skyfishjy/443b7448f59be978bc59 | |
* and https://github.com/flzyup/ExRecyclerViewLibrary/blob/master/recyclerview/src/main/java/android/support/v7/widget/CursorAdapter.java | |
* Created by ralphpina on 4/28/15. | |
*/ | |
public abstract class RecyclerViewCursorAdapter<VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> { | |
/** | |
* Call when bind view with the cursor | |
* | |
* @param holder | |
* @param cursor | |
*/ | |
public abstract void onBindViewHolder(VH holder, Cursor cursor); | |
/** | |
* This field should be made private, so it is hidden from the SDK. | |
* {@hide} | |
*/ | |
protected boolean mDataValid; | |
/** | |
* The current cursor | |
*/ | |
protected Cursor mCursor; | |
/** | |
* This field should be made private, so it is hidden from the SDK. | |
* {@hide} | |
*/ | |
protected Context mContext; | |
/** | |
* The row id column | |
*/ | |
protected int mRowIDColumn; | |
/** | |
* This field should be made private, so it is hidden from the SDK. | |
* {@hide} | |
*/ | |
protected ChangeObserver mChangeObserver; | |
/** | |
* This field should be made private, so it is hidden from the SDK. | |
* {@hide} | |
*/ | |
protected DataSetObserver mDataSetObserver; | |
/** | |
* If set the adapter will register a content observer on the cursor and will call | |
* {@link #onContentChanged()} when a notification comes in. Be careful when | |
* using this flag: you will need to unset the current Cursor from the adapter | |
* to avoid leaks due to its registered observers. This flag is not needed | |
* when using a CursorAdapter with a | |
* {@link android.content.CursorLoader}. | |
*/ | |
public static final int FLAG_REGISTER_CONTENT_OBSERVER = 0x02; | |
/** | |
* Recommended constructor. | |
* | |
* @param c The cursor from which to get the data. | |
* @param context The context | |
* @param flags Flags used to determine the behavior of the adapter; | |
* Currently it accept {@link #FLAG_REGISTER_CONTENT_OBSERVER}. | |
*/ | |
public RecyclerViewCursorAdapter(Context context, Cursor c, int flags) { | |
init(context, c, flags); | |
} | |
void init(Context context, Cursor c, int flags) { | |
boolean cursorPresent = false; | |
if (c != null) { | |
cursorPresent = true; | |
} | |
mCursor = c; | |
mDataValid = cursorPresent; | |
mContext = context; | |
mRowIDColumn = mDataValid ? mCursor.getColumnIndexOrThrow("_id") : -1; | |
if ((flags & FLAG_REGISTER_CONTENT_OBSERVER) == FLAG_REGISTER_CONTENT_OBSERVER) { | |
mChangeObserver = new ChangeObserver(); | |
mDataSetObserver = new MyDataSetObserver(); | |
} else { | |
mChangeObserver = null; | |
mDataSetObserver = null; | |
} | |
if (cursorPresent) { | |
if (mChangeObserver != null) mCursor.registerContentObserver(mChangeObserver); | |
if (mDataSetObserver != null) mCursor.registerDataSetObserver(mDataSetObserver); | |
} | |
setHasStableIds(true); | |
} | |
/** | |
* Returns the cursor. | |
* | |
* @return the cursor. | |
*/ | |
public Cursor getCursor() { | |
return mCursor; | |
} | |
/** | |
* @see android.support.v7.widget.RecyclerView.Adapter#getItemCount() | |
*/ | |
@Override | |
public int getItemCount() { | |
if (mDataValid && mCursor != null) { | |
return mCursor.getCount(); | |
} else { | |
return 0; | |
} | |
} | |
/** | |
* @param position Adapter position to query | |
* @return | |
* @see android.support.v7.widget.RecyclerView.Adapter#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; | |
} | |
} | |
@Override | |
public 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); | |
} | |
/** | |
* 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 | |
notifyDataSetChanged(); | |
} | |
return oldCursor; | |
} | |
/** | |
* Called when the {@link ContentObserver} on the cursor receives a change notification. | |
* The default implementation provides the auto-requery logic, but may be overridden by | |
* sub classes. | |
* | |
* @see ContentObserver#onChange(boolean) | |
*/ | |
protected abstract 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() { | |
super.onChanged(); | |
mDataValid = true; | |
notifyDataSetChanged(); | |
} | |
@Override | |
public void onInvalidated() { | |
super.onInvalidated(); | |
mDataValid = false; | |
notifyDataSetChanged(); | |
} | |
} | |
} |
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