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POSetting default values of multiple SharedPreferences instances/files
 

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  1. POSetting default values of multiple SharedPreferences instances/files
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    <p>Suppose that I have an application which saves preferences onto two files, <em>preferences1.xml</em> and <em>preferences2.xml</em>. Then, I can retrieve references to the corresponding objects with the following code:</p> <pre><code>SharedPreferences sharedPrefs1 = getSharedPreferences("preferences1", MODE_PRIVATE); SharedPreferences sharedPrefs2 = getSharedPreferences("preferences2", MODE_PRIVATE); </code></pre> <p>In this way I can manipulate the preferences for both and register listeners for changes on both.</p> <p>I have some doubts about the initialization of those two files, with <em>setDefaultValues</em>:</p> <p><strong>Question 1 - PreferenceFragment context</strong>: I've created a <em>PreferenceActivity</em> with two <em>PreferenceFragments</em> and within the <em>onCreate</em> method of each one I execute the following code (replace X with 1 and 2 for fragment 1 and 2):</p> <pre><code>PreferenceManager pm = getPreferenceManager(); pm.setSharedPreferencesName("preferencesX"); PreferenceManager.setDefaultValues(getActivity(),R.xml.preference_fragmentX, false); </code></pre> <p>I've seen that both fragments correctly set their preferences with their default values when launched.. but, given the fact that I can see only a single <strong>_has_set_default_values.xml</strong> file in the <strong>shared_prefs</strong> directory of the app, how does it understand when properties of <em>preferences1.xml</em> and <em>preferences2.xml</em> have been already set? This file is created as soon as <em>setDefaultValues</em> is called in the first opened <em>PreferenceFragment</em>, but even after that, if I open the second <em>PreferenceFragment</em> it correctly initializes default values. How does it understand that it has not yet initialized <em>preferences2.xml</em> and what is the purpose of <strong>_has_set_default_values.xml</strong> given the fact that it does not contains information about which prefereces files have been initialized?</p> <p><strong>Question 2 - Standard Activity context</strong>: when I start my app, the <em>PreferenceActivity</em> is not the first activity started and the user may never open it, so I'd like to initialize the two preference files with their default values also in the main <em>Activity</em>, how can I do that? For default shared preferences it is easy:</p> <pre><code>PreferenceManager.setDefaultValues(this, R.xml.default_preferences, false); </code></pre> <p>For two preference files how should I do? I can not do something like the following since I can not retrieve an instance of <em>PreferenceManager</em> like in the <em>PreferenceFragment</em> classes:</p> <pre><code>PreferenceManager pm = getPreferenceManager(); // NOT AVAILABLE AND NOT WANTED pm.setSharedPreferencesName("preferences1"); PreferenceManager.setDefaultValues(getActivity(),R.xml.preference_fragment1, false); PreferenceManager pm = getPreferenceManager(); // NOT AVAILABLE AND NOT WANTED pm.setSharedPreferencesName("preferences2"); PreferenceManager.setDefaultValues(getActivity(),R.xml.preference_fragment2, false); </code></pre> <p>Here in the main Activity I do not have the need to change the preference files on which the <em>PreferenceManager</em> will work, since we're not in a <em>PreferenceActivity</em>, I simply want to initialize those two files... any help? I hope I've posted a clear question, even if too long.</p>
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    1. USGianni Costanzi
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      1. UScrazymaik
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    1. CO@crazymaik I've deleted my answer as I don't think it answers the question satisfactorily. I've spent some hours looking into this by now, and it's still a complete mystery...Hope someone else can shed some light on it.
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      1. USGunnar Karlsson
    2. COcan u plz explain more on SO Chat?
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      1. USKOTIOS
    3. COtry using a .Namespace prefix within a Single physical file to manage 2 logical sets or categories of prefs within single filehandle. Your respective fragments should be able to apply the NS prefix in a manner that is not too disruptive to your CRUD operations on the pref properties.
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      1. USRobert Rowntree
 

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