如何设置 ListPreference 的默认值

Question

i need to set the defult value for a ListPreference when the Activity starts. I've tried with ListPreference.setDefaultvalue("value"); but it makes the firts Entry of the List as default. I need it because i must check a condition and set as default the value which satisfies that condition, so I think it can't be done from the xml file (with android:defaultValue )

For example, suppose I have this array of values in the arrays.xml:

<string-array name="opts">
    <item>red</item>
    <item>green</item>
    <item>blue</item>
</string-array>

<string-array name="opts_values">
    <item>1</item>
    <item>2</item>
    <item>3</item>
</string-array>

In the PreferenceScreen xml:

<ListPreference
    android:title="Colour select"
    android:summary="Select your favourite"
    android:key="colour"
    android:entries="@array/opts"
    android:entryValues="@array/opts_values" />

In the Activity I'd like to do something like this:

String mycolour;
if (something) {
    mycolour="1";
} else {
    mycolour="2";
}
ListPreference colour = (ListPreference) findPreference ("colour");
colour.setDefaultValue(mycolour);

But it doesn't work, because it makes the first choice as default. Could you explain me how to make another one as default? Thanks.

Answer 1

You don't need to programmatically handle the default value of ListPreferences . You can do this in xml setting file. Below is an example

<string-array name="opts">
    <item>red</item>
    <item>green</item>
    <item>blue</item>
</string-array>

<string-array name="opts_values">
    <item>1</item>
    <item>2</item>
    <item>3</item>
</string-array>

...

<ListPreference
    android:title="Colour select"
    android:summary="Select your favourite"
    android:key="colour"
    android:entries="@array/opts"
    android:entryValues="@array/opts_values"
    android:defaultValue="2" />

here I selected 2 as a default value. Remember defaultvalue will be opts_values element.

Answer 2

你有没有尝试过：

setValueIndex(int index);

Answer 3

Sorry my bad English.

1. List item
2. Retrieve the list Check if the value is null. If it is null set to the default value.

Code:

ListPreference dataPref = (ListPreference) findPreference("keyList");

if(dataPref.getValue() == null){
    dataPref.setValueIndex(0); //set to index of your deafult value
}

Answer 4

You can set your default value by using the key like this

<string-array name="syncFrequency">
    <item name="1">Block All Calls</item>
    <item name="2">Block Black List</item>
    <item name="3">Block Unknown Calls</item>
    <item name="4">Allow White List</item>
    <item name="5">Receive All Calls</item>
</string-array>




<string-array name="syncFrequencyValues">
    <item name="1">Block_All_Calls</item>
    <item name="2">Block_Black_List</item>
    <item name="3">Block_Unknown_Calls</item>
    <item name="4">Allow_White_List</item>
    <item name="5">Receive_All_Calls</item>
</string-array>



     <ListPreference
        android:key="prefSyncFrequency"
        android:entries="@array/syncFrequency"
        android:summary="%s"
        android:defaultValue="Block_Black_List"
        android:entryValues="@array/syncFrequencyValues"
        android:title="@string/call_block_options" />

Answer 5

或者你也可以试试colour.setValue(mycolour);

Answer 6

Just for the record if someone else has this problem:

setValueIndex(int X) is setting the value @ index X to the default value - so it is probably what you are looking for .

Set this value AFTER you added the Values! (stupid mistake but took me half an hour)

Answer 7

((ListPreference) findPreference("pref_language")).setValue(Locale
                .getDefault().getLanguage());

setValue() is ListPreference's method, and setDefaultvalue is Preference's method

Answer 8

Actually it's because the SharedPreferences will persist after you re-build the app. Uninstall it and try again.

Answer 9

这是一篇旧帖子，但这是使用以下代码行设置ListPreference的默认值的另一种方法：

PreferenceManager.setDefaultValues(getActivity(), R.xml.preferences, false);

Answer 10

Use the xml attribute android:defaultValue="<VALUE>" in your list tag to set the default value.

Note: the <VALUE> is the actual value and not the index of string array.

If still its not working, try below steps.

• Clear application data.
• Uninstall and reinstall the app
• Check the list preference, you will see the default value selected

Strange, I know but it worked in my case.

Answer 11

If you are using Android Jetpack Preference, known as androidx.preference:preference-ktx:1.1.1 in Kotlin, you can use:

app:defaultValue="<Value_in_string-array_with_values>" .

Additionally: defaultValue is not an index number, is the actual value from the values array.

I also recommend using a string resource for the default value and clearing the data, uninstalling the app , or removing the file:

• <package_name_in_app_manifest>_preferences.xml in data/data/shared_prefs/<package_name_in_app_manifest> . Replace <package_name_in_app_manifest> with real name like com.example.yourapp .

I was having the same issue and the defaultValue wasn't updating because it already had a wrong default value of "true". Solved it by using the Android Studio File Explorer and deleting the file.

And here is my solution example:

res/xml/root_preferences.xml

<ListPreference
    
    app:key="mic"
    
    app:title="@string/select_mic_title"
 
    app:useSimpleSummaryProvider="true"
   
    app:entries="@array/mic_entries"

    app:entryValues="@array/mic_values"
    app:defaultValue="@string/default_mic"
    />

res/values/arrays

<!-- Mic Preference -->

<string-array name="mic_entries">

    <item>@string/default_mic</item>

    <item>Headband</item>

</string-array>


<string-array name="mic_values">

    <item>@string/default_mic</item>

    <item>Headband</item>

</string-array>

res/strings.xml

<string name="default_mic">Integrated</string>

Result: Setting Fragment with default list value of "Integrated" given by string resource @string/default_mic