1 /*
2  * Copyright (C) 2012 Google Inc.
3  * Licensed to The Android Open Source Project.
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  *      http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17 
18 package com.android.mail.providers;
19 
20 import android.database.DataSetObserver;
21 
22 import com.android.mail.ui.AccountController;
23 import com.android.mail.utils.LogTag;
24 import com.android.mail.utils.LogUtils;
25 
26 /**
27  * A simple extension of {@link DataSetObserver} to provide the updated account in
28  * {@link #onChanged(Account)} when the account changes. Initializing the object registers with
29  * the observer with the {@link AccountController} provided. The object will then begin to
30  * receive {@link #onChanged(Account)} till {@link #unregisterAndDestroy()} is called.
31  * <p>
32  * To implement an {@link AccountObserver}, you need to implement the {@link #onChanged(Account)}
33  * method.
34  */
35 public abstract class AccountObserver extends DataSetObserver {
36     /**
37      * The AccountController that the observer is registered with.
38      */
39     private AccountController mController;
40 
41     private static final String LOG_TAG = LogTag.getLogTag();
42 
43     /**
44      * The no-argument constructor leaves the object unusable till
45      * {@link #initialize(AccountController)} is called.
46      */
AccountObserver()47     public AccountObserver () {
48     }
49 
50     /**
51      * Initializes an {@link AccountObserver} object that receives a call to
52      * {@link #onChanged(Account)} when the controller changes the account.
53      *
54      * @param controller
55      */
initialize(AccountController controller)56     public Account initialize(AccountController controller) {
57         if (controller == null) {
58             LogUtils.wtf(LOG_TAG, "AccountObserver initialized with null controller!");
59         }
60         mController = controller;
61         mController.registerAccountObserver(this);
62         return mController.getAccount();
63     }
64 
65     @Override
onChanged()66     public final void onChanged() {
67         if (mController == null) {
68             return;
69         }
70         onChanged(mController.getAccount());
71     }
72 
73     /**
74      * Callback invoked when the account object is changed.  Since {@link Account} objects are
75      * immutable, updates can be received on changes to individual settings (sync on/off)
76      * in addition to changes of accounts: alice@example.com -> bob@example.com.
77      * The updated account is passed as the argument.
78      * @param newAccount
79      */
onChanged(Account newAccount)80     public abstract void onChanged(Account newAccount);
81 
82     /**
83      * Return the most current account.
84      * @return
85      */
getAccount()86     public final Account getAccount() {
87         if (mController == null) {
88             return null;
89         }
90         return mController.getAccount();
91     }
92 
93     /**
94      * Unregisters for account changes and makes the object unusable.
95      */
unregisterAndDestroy()96     public void unregisterAndDestroy() {
97         if (mController == null) {
98             return;
99         }
100         mController.unregisterAccountObserver(this);
101     }
102 }