public abstract class CursorAdapter extends BaseAdapter implements Filterable,
CursorFilter.CursorFilterClient {
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protected ChangeObserver mChangeObserver;
/**
* This field should be made private, so it is hidden from the SDK.
* {@hide}
*/
protected DataSetObserver mDataSetObserver = new MyDataSetObserver();
/**
* This field should be made private, so it is hidden from the SDK.
* {@hide}
*/
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public CursorAdapter(Context context, Cursor c) {
init(context, c, true);
}
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protected void init(Context context, Cursor c, boolean autoRequery) {
boolean cursorPresent = c != null;
mAutoRequery = autoRequery;
mCursor = c;
mDataValid = cursorPresent;
mContext = context;
mRowIDColumn = cursorPresent ? c.getColumnIndexOrThrow("_id") : -1;
mChangeObserver = new ChangeObserver();
if (cursorPresent) {
c.registerContentObserver(mChangeObserver);
c.registerDataSetObserver(mDataSetObserver);
}
}
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/**
* 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) {
if (cursor == mCursor) {
return;
}
if (mCursor != null) {
mCursor.unregisterContentObserver(mChangeObserver);
mCursor.unregisterDataSetObserver(mDataSetObserver);
mCursor.close();
}
mCursor = cursor;
if (cursor != null) {
cursor.registerContentObserver(mChangeObserver);
cursor.registerDataSetObserver(mDataSetObserver);
mRowIDColumn = cursor.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();
}
}
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/**
* 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 void onContentChanged() {
if (mAutoRequery && mCursor != null && !mCursor.isClosed()) {
if (Config.LOGV) Log.v("Cursor", "Auto requerying " + mCursor + " due to update");
mDataValid = mCursor.requery();
}
}
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();
}
}
}
