1 /* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License 15 */ 16 17 package com.android.contacts.common.database; 18 19 import android.content.AsyncQueryHandler; 20 import android.content.ContentResolver; 21 import android.database.Cursor; 22 import android.net.Uri; 23 24 /** 25 * An {@AsyncQueryHandler} that will never return a null cursor. 26 * <p> 27 * Instead, will return a {@link Cursor} with 0 records. 28 */ 29 public abstract class NoNullCursorAsyncQueryHandler extends AsyncQueryHandler { 30 31 public NoNullCursorAsyncQueryHandler(ContentResolver cr) { 32 super(cr); 33 } 34 35 @Override 36 public void startQuery(int token, Object cookie, Uri uri, String[] projection, String selection, 37 String[] selectionArgs, String orderBy) { 38 final CookieWithProjection projectionCookie = new CookieWithProjection(cookie, projection); 39 super.startQuery(token, projectionCookie, uri, projection, selection, selectionArgs, 40 orderBy); 41 } 42 43 @Override 44 protected final void onQueryComplete(int token, Object cookie, Cursor cursor) { 45 CookieWithProjection projectionCookie = (CookieWithProjection) cookie; 46 47 super.onQueryComplete(token, projectionCookie.originalCookie, cursor); 48 49 if (cursor == null) { 50 cursor = new EmptyCursor(projectionCookie.projection); 51 } 52 onNotNullableQueryComplete(token, projectionCookie.originalCookie, cursor); 53 } 54 55 protected abstract void onNotNullableQueryComplete(int token, Object cookie, Cursor cursor); 56 57 /** 58 * Class to add projection to an existing cookie. 59 */ 60 private static class CookieWithProjection { 61 public final Object originalCookie; 62 public final String[] projection; 63 64 public CookieWithProjection(Object cookie, String[] projection) { 65 this.originalCookie = cookie; 66 this.projection = projection; 67 } 68 } 69 } 70
