MultiSelectList preference不存储价值？ [英] MultiSelectListPreference not storing values?

问题描述

我是相当新的Andr​​oid应用程序开发，所以也许我只是做一个简单的新手的错误，但这里是我的问题： 我有2个简单的活动，MainActivity和SettingsActivity。在MainActivity我有一个按钮，显示SettingsActivity。在SettingsActivity我包括preferenceFragment SettingsFragment，并在活动的底部显示一个按钮栏。内SettingsFragment我有一个MultiSelectList preference定义如下：

I'm rather new to Android App developing so maybe I'm just making a simple newbie mistake, but here's my problem: I have 2 simple Activities, MainActivity and SettingsActivity. In MainActivity I have a button which displays SettingsActivity. Within SettingsActivity I include a PreferenceFragment SettingsFragment and display a ButtonBar at the bottom of the Activity. Within the SettingsFragment I have a MultiSelectListPreference defined as follows:

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >
    <PreferenceCategory 
        android:title="@string/title_schedule_settings">

        <MultiSelectListPreference
            android:key="@string/key_list_schedule"
            android:title="@string/title_schedule_list"
            android:dialogTitle="@string/title_schedule_list"
            android:entries="@array/list_weekdays"
            android:entryValues="@array/list_weekdays"
            android:defaultValue="@array/empty_list"
            android:persistent="true"/>
    </PreferenceCategory>

</PreferenceScreen>

现在，当我选择了preference它让我看到列表中的所有条目的数组中定义的，我可以选择多个条目，当我确认对话框中的值实际上存储在共享$ P $定义项下pferences。但是，如果我现在再次显示preference它会告诉我，选择pviously选定项目$ P $，但值不再存储在共享preferences内，经过一番摆弄周围，我不得不意识到，在共享preferences价值观显然得到尽快所示的对话框中抹去。

Now when I select that Preference it shows me the list with all the entries as defined in the array, I can select multiple entries and when I confirm the dialog the values are in fact stored in the SharedPreferences under the defined key. But if I now show the Preference again it will show me previously selected items as selected, but the values are no longer stored within the SharedPreferences, and after some fiddling around I had to realize that the values in the SharedPreferences apparently get wiped as soon as the dialog is shown.

所以，现在我的问题是：这是正常/预期的行为或者这是一个错误？我怎样才能解决此问题？ 我已经尝试过让我自己执行MultiSelectList preference并覆盖像这样的prepareDialogBu​​ilder方法

So now my questions are: is this normal/intended behavior or is this a bug? And how can I work around this? I already tried making my own implementation of MultiSelectListPreference and override the onPrepareDialogBuilder method like this

@Override
protected void onPrepareDialogBuilder(AlertDialog.Builder builder)
{
    super.onPrepareDialogBuilder(builder);

    Log.i("mmslp", Arrays.deepToString(PreferenceManager.getDefaultSharedPreferences(getContext()).getStringSet(getKey(), new HashSet<String>()).toArray()));
    setValues(PreferenceManager.getDefaultSharedPreferences(getContext()).getStringSet(getKey(), new HashSet<String>()));
}

但值显然已经消灭了这一点。

but the values are apparently wiped already at this point.

推荐答案

我花了一些时间昨天就这个问题和我现在相信，它的目的不是这样的，但实际上打破 - 有人迷惑参考指针类型和价值。 ; - ）

I spent some time yesterday on this and am now convinced that it is not intended like that, but actually broken - someone confused reference by pointer and by value. ;-)

好像（自4.1）虽然被定格在了Android的更新的版本： <一href="https://$c$c.google.com/p/android/issues/detail?id=22807">https://$c$c.google.com/p/android/issues/detail?id=22807

Seems to be fixed in the more current versions of Android (since 4.1) though: https://code.google.com/p/android/issues/detail?id=22807

我解决了，现在为Android的previous版本的方式是覆盖在我的执行MultiSelectList preference setValues​​方法将和公正的值复制到一个新的对象：

The way I solved it now for the previous versions of Android is to override the setValues method in my implementation of MultiSelectListPreference and just copy the values into a new object:

@Override
public void setValues( Set<String> values ) {

    //Workaround for https://code.google.com/p/android/issues/detail?id=22807
    final Set<String> newValues = new HashSet<String>();
    newValues.addAll( values );
    super.setValues( newValues );
}

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