Initialize preferences from XML in the main Activity

Question

My problem is that when I start application and user didn't open my PreferenceActivity so when I retrieve them don't get any default values defined in my preference.xml file.

preference.xml file:

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
    android:key="applicationPreference" android:title="@string/config"
    >
    <ListPreference
            android:key="pref1"
            android:defaultValue="default"
            android:title="Title"
            android:summary="Summary"
            android:entries="@array/entry_names"
            android:entryValues="@array/entry_values"
            android:dialogTitle="@string/dialog_title"
    />                  
</PreferenceScreen>

Snippet from my main Activity (onCreate method):

    SharedPreferences appPreferences = PreferenceManager.getDefaultSharedPreferences(this);        
    String pref1 = appPreferences.getString("pref1", null);

In result I end up with a null value.

score 112 · Accepted Answer · answered May 20 '10 at 15:39

112

In onCreate() of your main Activity just call the PreferenceManager.setDefaultValues() method.

PreferenceManager.setDefaultValues(this, R.xml.preference, false);

This will read your preference.xml file and set the default values defined there. Setting the readAgain argument to false means this will only set the default values if this method has never been called in the past so you don't need to worry about overriding the user's settings each time your Activity is created.

answered May 20 '10 at 15:39

David Webb

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but anyone have the sample or template for this perference.xml for reference? – Joe Ho Apr 06 '11 at 06:26
8

You saved my day! Been looking for 3 hours at the null value, at 3 'o clock at night in an airport wit tethering wifi. Thanks! – Cimm May 27 '11 at 02:56
1

@Dave Webb This does not work for string preferences. – Anderson Nov 29 '12 at 15:19
2

Setting `readAgain` to true has nothing to do with overriding the user's settings. From the Javadoc: _Note: this will NOT reset preferences back to their default values._ – devconsole Jan 02 '14 at 18:53
1

How does this work when new settings are added in updates? They won't be initialized, will they? – Nathan Osman May 10 '15 at 22:37
How to reset the specific key to its default value. – Ganesh Jogam Aug 14 '17 at 08:29

score 14 · Answer 2 · answered May 20 '10 at 15:10

14

I'll be brief. :)

strings.xml (actually I have prefs.xml exclusively for preferences):

<string name="pref_mypref_key">mypref</string>
<string name="pref_mypref_default">blah</string>

preferences.xml:

android:key="@string/pref_mypref_key"
android:defaultValue="@string/pref_mypref_default"

MyActivity.java:

String myprefVal = prefs.getString(getString(R.string.pref_mypref_key), getString(R.string.pref_mypref_default));

answered May 20 '10 at 15:10

yanchenko

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Thanks, this actually is answer to my another question about where to store preference keys :) If I'll be able to combine it with best answer to this question it will be great! – pixel May 20 '10 at 19:04
2

Apparently, in this example, this line would appear in `MyActivity.java` before the assignment of `myprefVal`: `SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);` – hotshot309 Dec 30 '11 at 17:01
4

This works, but should this really be necessary? – JohnyTex Oct 16 '14 at 18:51

score 8 · Answer 3 · answered May 20 '10 at 14:09

8

Your call to getString() has null as the second parameter. Change that to be the default value you want.

answered May 20 '10 at 14:09

CommonsWare

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This is a very elegant solution. +1. However, to achieve what the OP wanted, the PreferenceManager.setDefaultValues() is the solution. – ef2011 May 09 '11 at 01:58

Initialize preferences from XML in the main Activity

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