Initialize preferences from XML in the main Activity [duplicate]

问题

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.

回答1:

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.

回答2:

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));

回答3:

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

来源：https://stackoverflow.com/questions/2874276/initialize-preferences-from-xml-in-the-main-activity

标签

android

xml

android-preferences