Android PreferenceScreen - Can I use it without saving preferences to SharedPreferences?

问题

I'm trying to use the Android PreferenceScreen as a convenient way to layout my user settings, but I don't want to save the preferences to the device shared preferences. Is this possible, or should I be using a different mechanism such as ListView?

It seems really convenient to use the PreferenceScreen type because I require different widgets (ie. switches, edit text). But I'm already running into problems with persistence, ie. anything I enter is persisted even across sessions when I don't want it to be.

settings.xml:

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <Preference
        android:key="settings_type"
        android:title="@string/label_type" />

    <EditTextPreference
        android:key="settings_edit_name"
        android:title="@string/label_name"
        android:dialogTitle="Enter a name"
        android:singleLine="true" />

    <SwitchPreference
        android:key="settings_edit_state"
        android:title="@string/label_state"
        android:summary="Enable or disable the state" />

</PreferenceScreen>

回答1:

You can just use a linear layout and place the non-preference versions of the components you want in it.

回答2:

I know that's an old question but I find it quite interesting. Just set this attribute to your preference and it won't be saved:

android:persistent="false"

回答3:

I re-read the appropriate docs and determined how to prevent saving preferences by implementing the Preference.OnPreferenceChangeListener interface.

public static interface Preference.OnPreferenceChangeListener

Interface definition for a callback to be invoked when the value of this Preference has been changed by the user and is about to be set and/or persisted. This gives the client a chance to prevent setting and/or persisting the value.

Example:

public class SettingsFragment extends PreferenceFragment {

    public static SettingsFragment newInstance(int index) {
        SettingsFragment f = new SettingsFragment();

        Bundle args = new Bundle();
        args.putInt("index", index);
        f.setArguments(args);

        return f;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        addPreferencesFromResource(R.layout.settings);

        // getArguments().getInt("index");

        EditTextPreference namePreference = (EditTextPreference) findPreference("settings_edit_name");
        namePreference.setOnPreferenceChangeListener(new NamePreferenceChangeListener());

    }

    private class NamePreferenceChangeListener implements Preference.OnPreferenceChangeListener {

    @Override
    public boolean onPreferenceChange(Preference preference, Object newValue) {
        // Do something else presumably and then return false to avoid saving the pref.
        return false;
    }

}

回答4:

Since the preferences are bound to be stored, you can always clear them in onCreate

Try this in onCreate of PreferenceFragment

super.onCreate();
getPreferenceManager().setSharedPreferencesName("custom");
SharedPreferences sp = getPreferenceManager().getSharedPreferences();
SharedPreferences.Editor editor = sp.edit();
editor.clear();
editor.apply();

回答5:

I recommend creating a subclass of PreferenceDataStore and assigning it to your PreferenceManager.

Preference Data Store

A data store interface to be implemented and provided to the Preference framework. This can be used to replace the default android.content.SharedPreferences, if needed.

• https://developer.android.com/reference/kotlin/androidx/preference/PreferenceDataStore

PreferenceManager

public void setPreferenceDataStore (PreferenceDataStore dataStore)

Sets a PreferenceDataStore to be used by all preferences associated with this manager that don't have a custom PreferenceDataStore assigned via Preference.setPreferenceDataStore(PreferenceDataStore). Also if the data store is set, the child preferences won't use SharedPreferences as long as they are assigned to this manager.

• https://developer.android.com/reference/androidx/preference/PreferenceManager#setPreferenceDataStore(androidx.preference.PreferenceDataStore)

Example

CustomDataStore

    class CustomDataStore: PreferenceDataStore() {
    override fun putBoolean(key: String?, value: Boolean) {
        when (key) {
            knownKey -> // Do something
            anotherKnownKey -> // Do somthing else
        }
    }

    override fun putString(key: String?, value: String?) {
        when (key) {
            knownKey -> // Do something
            anotherKnownKey -> // Do something else
        }
    }

    // You can ignore unused types but make sure to still override to avoid UnsupportedOperationException
    override fun putFloat(key: String?, value: Float) {}
    override fun putInt(key: String?, value: Int) {}
    override fun putLong(key: String?, value: Long) {}
    override fun putStringSet(key: String?, values: MutableSet<String>?) {}

    override fun getBoolean(key: String?, defValue: Boolean): Boolean {
        return when (key) {
            knownKey -> // Do something
            anotherKnownKey -> // Do something else
            else -> defValue
        }
    }

    override fun getString(key: String?, defValue: String?): String? {
        return when (key) {
            knownKey -> // Do something
            anotherKnownKey -> // Do something else
            else -> defValue
        }
    }
}

NOTE: Be careful while subclassing, because all the abstract put() methods will throw an UnsupportedOperationException.

PreferenceFragment or PreferenceFragmentCompat

override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
    // Prevent saving to SharedPreferences, use a custom data store
    preferenceManager.preferenceDataStore = CustomDataStore()
}

来源：https://stackoverflow.com/questions/14633351/android-preferencescreen-can-i-use-it-without-saving-preferences-to-sharedpref