sdk/sources/android-25/android/widget/CursorAdapter.java - android_tools - Git at Google

 /*
  * Copyright (C) 2006 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package android.widget;

 import android.annotation.WorkerThread;
 import android.content.Context;
 import android.content.res.Resources;
 import android.database.ContentObserver;
 import android.database.Cursor;
 import android.database.DataSetObserver;
 import android.os.Handler;
 import android.util.Log;
 import android.view.ContextThemeWrapper;
 import android.view.View;
 import android.view.ViewGroup;

 /**
  * Adapter that exposes data from a {@link android.database.Cursor Cursor} to a
  * {@link android.widget.ListView ListView} widget.
  * <p>
  * The Cursor must include a column named "_id" or this class will not work.
  * Additionally, using {@link android.database.MergeCursor} with this class will
  * not work if the merged Cursors have overlapping values in their "_id"
  * columns.
  */
 public abstract class CursorAdapter extends BaseAdapter implements Filterable,
         CursorFilter.CursorFilterClient, ThemedSpinnerAdapter {
     /**
      * This field should be made private, so it is hidden from the SDK.
      * {@hide}
      */
     protected boolean mDataValid;
     /**
      * This field should be made private, so it is hidden from the SDK.
      * {@hide}
      */
     protected boolean mAutoRequery;
     /**
      * This field should be made private, so it is hidden from the SDK.
      * {@hide}
      */
     protected Cursor mCursor;
     /**
      * This field should be made private, so it is hidden from the SDK.
      * {@hide}
      */
     protected Context mContext;
     /**
      * Context used for {@link #getDropDownView(int, View, ViewGroup)}.
      * {@hide}
      */
     protected Context mDropDownContext;
     /**
      * This field should be made private, so it is hidden from the SDK.
      * {@hide}
      */
     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;
     /**
      * This field should be made private, so it is hidden from the SDK.
      * {@hide}
      */
     protected CursorFilter mCursorFilter;
     /**
      * This field should be made private, so it is hidden from the SDK.
      * {@hide}
      */
     protected FilterQueryProvider mFilterQueryProvider;

     /**
      * If set the adapter will call requery() on the cursor whenever a content change
      * notification is delivered. Implies {@link #FLAG_REGISTER_CONTENT_OBSERVER}.
      *
      * @deprecated This option is discouraged, as it results in Cursor queries
      * being performed on the application's UI thread and thus can cause poor
      * responsiveness or even Application Not Responding errors.  As an alternative,
      * use {@link android.app.LoaderManager} with a {@link android.content.CursorLoader}.
      */
     @Deprecated
     public static final int FLAG_AUTO_REQUERY = 0x01;

     /**
      * 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;

     /**
      * Constructor that always enables auto-requery.
      *
      * @deprecated This option is discouraged, as it results in Cursor queries
      * being performed on the application's UI thread and thus can cause poor
      * responsiveness or even Application Not Responding errors.  As an alternative,
      * use {@link android.app.LoaderManager} with a {@link android.content.CursorLoader}.
      *
      * @param c The cursor from which to get the data.
      * @param context The context
      */
     @Deprecated
     public CursorAdapter(Context context, Cursor c) {
         init(context, c, FLAG_AUTO_REQUERY);
     }

     /**
      * Constructor that allows control over auto-requery.  It is recommended
      * you not use this, but instead {@link #CursorAdapter(Context, Cursor, int)}.
      * When using this constructor, {@link #FLAG_REGISTER_CONTENT_OBSERVER}
      * will always be set.
      *
      * @param c The cursor from which to get the data.
      * @param context The context
      * @param autoRequery If true the adapter will call requery() on the
      *                    cursor whenever it changes so the most recent
      *                    data is always displayed.  Using true here is discouraged.
      */
     public CursorAdapter(Context context, Cursor c, boolean autoRequery) {
         init(context, c, autoRequery ? FLAG_AUTO_REQUERY : FLAG_REGISTER_CONTENT_OBSERVER);
     }

     /**
      * 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; may
      * be any combination of {@link #FLAG_AUTO_REQUERY} and
      * {@link #FLAG_REGISTER_CONTENT_OBSERVER}.
      */
     public CursorAdapter(Context context, Cursor c, int flags) {
         init(context, c, flags);
     }

     /**
      * @deprecated Don't use this, use the normal constructor.  This will
      * be removed in the future.
      */
     @Deprecated
     protected void init(Context context, Cursor c, boolean autoRequery) {
         init(context, c, autoRequery ? FLAG_AUTO_REQUERY : FLAG_REGISTER_CONTENT_OBSERVER);
     }

     void init(Context context, Cursor c, int flags) {
         if ((flags & FLAG_AUTO_REQUERY) == FLAG_AUTO_REQUERY) {
             flags |= FLAG_REGISTER_CONTENT_OBSERVER;
             mAutoRequery = true;
         } else {
             mAutoRequery = false;
         }
         boolean cursorPresent = c != null;
         mCursor = c;
         mDataValid = cursorPresent;
         mContext = context;
         mRowIDColumn = cursorPresent ? c.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) c.registerContentObserver(mChangeObserver);
             if (mDataSetObserver != null) c.registerDataSetObserver(mDataSetObserver);
         }
     }

     /**
      * Sets the {@link Resources.Theme} against which drop-down views are
      * inflated.
      * <p>
      * By default, drop-down views are inflated against the theme of the
      * {@link Context} passed to the adapter's constructor.
      *
      * @param theme the theme against which to inflate drop-down views or
      *              {@code null} to use the theme from the adapter's context
      * @see #newDropDownView(Context, Cursor, ViewGroup)
      */
     @Override
     public void setDropDownViewTheme(Resources.Theme theme) {
         if (theme == null) {
             mDropDownContext = null;
         } else if (theme == mContext.getTheme()) {
             mDropDownContext = mContext;
         } else {
             mDropDownContext = new ContextThemeWrapper(mContext, theme);
         }
     }

     @Override
     public Resources.Theme getDropDownViewTheme() {
         return mDropDownContext == null ? null : mDropDownContext.getTheme();
     }

     /**
      * Returns the cursor.
      * @return the cursor.
      */
     public Cursor getCursor() {
         return mCursor;
     }

     /**
      * @see android.widget.ListAdapter#getCount()
      */
     public int getCount() {
         if (mDataValid && mCursor != null) {
             return mCursor.getCount();
         } else {
             return 0;
         }
     }

     /**
      * @see android.widget.ListAdapter#getItem(int)
      */
     public Object getItem(int position) {
         if (mDataValid && mCursor != null) {
             mCursor.moveToPosition(position);
             return mCursor;
         } else {
             return null;
         }
     }

     /**
      * @see android.widget.ListAdapter#getItemId(int)
      */
     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 boolean hasStableIds() {
         return true;
     }

     /**
      * @see android.widget.ListAdapter#getView(int, View, ViewGroup)
      */
     public View getView(int position, View convertView, ViewGroup parent) {
         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);
         }
         View v;
         if (convertView == null) {
             v = newView(mContext, mCursor, parent);
         } else {
             v = convertView;
         }
         bindView(v, mContext, mCursor);
         return v;
     }

     @Override
     public View getDropDownView(int position, View convertView, ViewGroup parent) {
         if (mDataValid) {
             final Context context = mDropDownContext == null ? mContext : mDropDownContext;
             mCursor.moveToPosition(position);
             final View v;
             if (convertView == null) {
                 v = newDropDownView(context, mCursor, parent);
             } else {
                 v = convertView;
             }
             bindView(v, context, mCursor);
             return v;
         } else {
             return null;
         }
     }

     /**
      * Makes a new view to hold the data pointed to by cursor.
      * @param context Interface to application's global information
      * @param cursor The cursor from which to get the data. The cursor is already
      * moved to the correct position.
      * @param parent The parent to which the new view is attached to
      * @return the newly created view.
      */
     public abstract View newView(Context context, Cursor cursor, ViewGroup parent);

     /**
      * Makes a new drop down view to hold the data pointed to by cursor.
      * @param context Interface to application's global information
      * @param cursor The cursor from which to get the data. The cursor is already
      * moved to the correct position.
      * @param parent The parent to which the new view is attached to
      * @return the newly created view.
      */
     public View newDropDownView(Context context, Cursor cursor, ViewGroup parent) {
         return newView(context, cursor, parent);
     }

     /**
      * Bind an existing view to the data pointed to by cursor
      * @param view Existing view, returned earlier by newView
      * @param context Interface to application's global information
      * @param cursor The cursor from which to get the data. The cursor is already
      * moved to the correct position.
      */
     public abstract void bindView(View view, Context context, Cursor cursor);

     /**
      * 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();
         }
         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)
      */
     @WorkerThread
     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.
      * 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 (false) 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();
         }
     }

 }
	/*
	* Copyright (C) 2006 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package android.widget;

	import android.annotation.WorkerThread;
	import android.content.Context;
	import android.content.res.Resources;
	import android.database.ContentObserver;
	import android.database.Cursor;
	import android.database.DataSetObserver;
	import android.os.Handler;
	import android.util.Log;
	import android.view.ContextThemeWrapper;
	import android.view.View;
	import android.view.ViewGroup;

	/**
	* Adapter that exposes data from a {@link android.database.Cursor Cursor} to a
	* {@link android.widget.ListView ListView} widget.
	* <p>
	* The Cursor must include a column named "_id" or this class will not work.
	* Additionally, using {@link android.database.MergeCursor} with this class will
	* not work if the merged Cursors have overlapping values in their "_id"
	* columns.
	*/
	public abstract class CursorAdapter extends BaseAdapter implements Filterable,
	CursorFilter.CursorFilterClient, ThemedSpinnerAdapter {
	/**
	* This field should be made private, so it is hidden from the SDK.
	* {@hide}
	*/
	protected boolean mDataValid;
	/**
	* This field should be made private, so it is hidden from the SDK.
	* {@hide}
	*/
	protected boolean mAutoRequery;
	/**
	* This field should be made private, so it is hidden from the SDK.
	* {@hide}
	*/
	protected Cursor mCursor;
	/**
	* This field should be made private, so it is hidden from the SDK.
	* {@hide}
	*/
	protected Context mContext;
	/**
	* Context used for {@link #getDropDownView(int, View, ViewGroup)}.
	* {@hide}
	*/
	protected Context mDropDownContext;
	/**
	* This field should be made private, so it is hidden from the SDK.
	* {@hide}
	*/
	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;
	/**
	* This field should be made private, so it is hidden from the SDK.
	* {@hide}
	*/
	protected CursorFilter mCursorFilter;
	/**
	* This field should be made private, so it is hidden from the SDK.
	* {@hide}
	*/
	protected FilterQueryProvider mFilterQueryProvider;

	/**
	* If set the adapter will call requery() on the cursor whenever a content change
	* notification is delivered. Implies {@link #FLAG_REGISTER_CONTENT_OBSERVER}.
	*
	* @deprecated This option is discouraged, as it results in Cursor queries
	* being performed on the application's UI thread and thus can cause poor
	* responsiveness or even Application Not Responding errors. As an alternative,
	* use {@link android.app.LoaderManager} with a {@link android.content.CursorLoader}.
	*/
	@Deprecated
	public static final int FLAG_AUTO_REQUERY = 0x01;

	/**
	* 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;

	/**
	* Constructor that always enables auto-requery.
	*
	* @deprecated This option is discouraged, as it results in Cursor queries
	* being performed on the application's UI thread and thus can cause poor
	* responsiveness or even Application Not Responding errors. As an alternative,
	* use {@link android.app.LoaderManager} with a {@link android.content.CursorLoader}.
	*
	* @param c The cursor from which to get the data.
	* @param context The context
	*/
	@Deprecated
	public CursorAdapter(Context context, Cursor c) {
	init(context, c, FLAG_AUTO_REQUERY);
	}

	/**
	* Constructor that allows control over auto-requery. It is recommended
	* you not use this, but instead {@link #CursorAdapter(Context, Cursor, int)}.
	* When using this constructor, {@link #FLAG_REGISTER_CONTENT_OBSERVER}
	* will always be set.
	*
	* @param c The cursor from which to get the data.
	* @param context The context
	* @param autoRequery If true the adapter will call requery() on the
	* cursor whenever it changes so the most recent
	* data is always displayed. Using true here is discouraged.
	*/
	public CursorAdapter(Context context, Cursor c, boolean autoRequery) {
	init(context, c, autoRequery ? FLAG_AUTO_REQUERY : FLAG_REGISTER_CONTENT_OBSERVER);
	}

	/**
	* 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; may
	* be any combination of {@link #FLAG_AUTO_REQUERY} and
	* {@link #FLAG_REGISTER_CONTENT_OBSERVER}.
	*/
	public CursorAdapter(Context context, Cursor c, int flags) {
	init(context, c, flags);
	}

	/**
	* @deprecated Don't use this, use the normal constructor. This will
	* be removed in the future.
	*/
	@Deprecated
	protected void init(Context context, Cursor c, boolean autoRequery) {
	init(context, c, autoRequery ? FLAG_AUTO_REQUERY : FLAG_REGISTER_CONTENT_OBSERVER);
	}

	void init(Context context, Cursor c, int flags) {
	if ((flags & FLAG_AUTO_REQUERY) == FLAG_AUTO_REQUERY) {
	flags \|= FLAG_REGISTER_CONTENT_OBSERVER;
	mAutoRequery = true;
	} else {
	mAutoRequery = false;
	}
	boolean cursorPresent = c != null;
	mCursor = c;
	mDataValid = cursorPresent;
	mContext = context;
	mRowIDColumn = cursorPresent ? c.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) c.registerContentObserver(mChangeObserver);
	if (mDataSetObserver != null) c.registerDataSetObserver(mDataSetObserver);
	}
	}

	/**
	* Sets the {@link Resources.Theme} against which drop-down views are
	* inflated.
	* <p>
	* By default, drop-down views are inflated against the theme of the
	* {@link Context} passed to the adapter's constructor.
	*
	* @param theme the theme against which to inflate drop-down views or
	* {@code null} to use the theme from the adapter's context
	* @see #newDropDownView(Context, Cursor, ViewGroup)
	*/
	@Override
	public void setDropDownViewTheme(Resources.Theme theme) {
	if (theme == null) {
	mDropDownContext = null;
	} else if (theme == mContext.getTheme()) {
	mDropDownContext = mContext;
	} else {
	mDropDownContext = new ContextThemeWrapper(mContext, theme);
	}
	}

	@Override
	public Resources.Theme getDropDownViewTheme() {
	return mDropDownContext == null ? null : mDropDownContext.getTheme();
	}

	/**
	* Returns the cursor.
	* @return the cursor.
	*/
	public Cursor getCursor() {
	return mCursor;
	}

	/**
	* @see android.widget.ListAdapter#getCount()
	*/
	public int getCount() {
	if (mDataValid && mCursor != null) {
	return mCursor.getCount();
	} else {
	return 0;
	}
	}

	/**
	* @see android.widget.ListAdapter#getItem(int)
	*/
	public Object getItem(int position) {
	if (mDataValid && mCursor != null) {
	mCursor.moveToPosition(position);
	return mCursor;
	} else {
	return null;
	}
	}

	/**
	* @see android.widget.ListAdapter#getItemId(int)
	*/
	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 boolean hasStableIds() {
	return true;
	}

	/**
	* @see android.widget.ListAdapter#getView(int, View, ViewGroup)
	*/
	public View getView(int position, View convertView, ViewGroup parent) {
	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);
	}
	View v;
	if (convertView == null) {
	v = newView(mContext, mCursor, parent);
	} else {
	v = convertView;
	}
	bindView(v, mContext, mCursor);
	return v;
	}

	@Override
	public View getDropDownView(int position, View convertView, ViewGroup parent) {
	if (mDataValid) {
	final Context context = mDropDownContext == null ? mContext : mDropDownContext;
	mCursor.moveToPosition(position);
	final View v;
	if (convertView == null) {
	v = newDropDownView(context, mCursor, parent);
	} else {
	v = convertView;
	}
	bindView(v, context, mCursor);
	return v;
	} else {
	return null;
	}
	}

	/**
	* Makes a new view to hold the data pointed to by cursor.
	* @param context Interface to application's global information
	* @param cursor The cursor from which to get the data. The cursor is already
	* moved to the correct position.
	* @param parent The parent to which the new view is attached to
	* @return the newly created view.
	*/
	public abstract View newView(Context context, Cursor cursor, ViewGroup parent);

	/**
	* Makes a new drop down view to hold the data pointed to by cursor.
	* @param context Interface to application's global information
	* @param cursor The cursor from which to get the data. The cursor is already
	* moved to the correct position.
	* @param parent The parent to which the new view is attached to
	* @return the newly created view.
	*/
	public View newDropDownView(Context context, Cursor cursor, ViewGroup parent) {
	return newView(context, cursor, parent);
	}

	/**
	* Bind an existing view to the data pointed to by cursor
	* @param view Existing view, returned earlier by newView
	* @param context Interface to application's global information
	* @param cursor The cursor from which to get the data. The cursor is already
	* moved to the correct position.
	*/
	public abstract void bindView(View view, Context context, Cursor cursor);

	/**
	* 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();
	}
	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)
	*/
	@WorkerThread
	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.
	* 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 (false) 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();
	}
	}

	}