谢谢Reto的详细解释!

为了对大家有所帮助，我不得不修改Reto Meier提出的代码，使其与Android 1.5的SDK兼容

@Override
protected void onResume() {
    super.onResume();

    // Setup the initial values
    mListPreference.setSummary("Current value is " + mListPreference.getEntry().toString()); 

    // Set up a listener whenever a key changes            
    ...
}

同样的变化适用于回调函数onSharedPreferenceChanged(SharedPreferences SharedPreferences, String key)

欢呼,

克里斯

要将ListPreference的摘要设置为对话框中选择的值，您可以使用以下代码:

package yourpackage;

import android.content.Context;
import android.util.AttributeSet;

public class ListPreference extends android.preference.ListPreference {

    public ListPreference(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    protected void onDialogClosed(boolean positiveResult) {
        super.onDialogClosed(positiveResult);
        if (positiveResult) setSummary(getEntry());
    }

    protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {
        super.onSetInitialValue(restoreValue, defaultValue);
        setSummary(getEntry());
    }
}

参考你的包。记住在你的preferences.xml中指定你的android:defaultValue作为触发onSetInitialValue()的调用。

如果您愿意，可以在调用setSummary()之前修改文本，以适合您的应用程序。

我的选择是扩展ListPreference，它是干净的:

public class ListPreferenceShowSummary extends ListPreference {

    private final static String TAG = ListPreferenceShowSummary.class.getName();

    public ListPreferenceShowSummary(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public ListPreferenceShowSummary(Context context) {
        super(context);
        init();
    }

    private void init() {

        setOnPreferenceChangeListener(new OnPreferenceChangeListener() {

            @Override
            public boolean onPreferenceChange(Preference arg0, Object arg1) {
                arg0.setSummary(getEntry());
                return true;
            }
        });
    }

    @Override
    public CharSequence getSummary() {
        return super.getEntry();
    }
}

然后你添加你的settings.xml:

<yourpackage.ListPreferenceShowSummary
    android:key="key" android:title="title"
    android:entries="@array/entries" android:entryValues="@array/values"
    android:defaultValue="first value"/>

Here,all these are cut from Eclipse sample SettingsActivity. I have to copy all these too much codes to show how these android developers choose perfectly for more generalized and stable coding style. I left the codes for adapting the PreferenceActivity to tablet and greater API. public class SettingsActivity extends PreferenceActivity { @Override protected void onPostCreate(Bundle savedInstanceState) { super.onPostCreate(savedInstanceState); setupSummaryUpdatablePreferencesScreen(); } private void setupSummaryUpdatablePreferencesScreen() { // In the simplified UI, fragments are not used at all and we instead // use the older PreferenceActivity APIs. // Add 'general' preferences. addPreferencesFromResource(R.xml.pref_general); // Bind the summaries of EditText/List/Dialog preferences to // their values. When their values change, their summaries are updated // to reflect the new value, per the Android Design guidelines. bindPreferenceSummaryToValue(findPreference("example_text")); bindPreferenceSummaryToValue(findPreference("example_list")); } /** * A preference value change listener that updates the preference's summary * to reflect its new value. */ private static Preference.OnPreferenceChangeListener sBindPreferenceSummaryToValueListener = new Preference.OnPreferenceChangeListener() { private String TAG = SettingsActivity.class.getSimpleName(); @Override public boolean onPreferenceChange(Preference preference, Object value) { String stringValue = value.toString(); if (preference instanceof ListPreference) { // For list preferences, look up the correct display value in // the preference's 'entries' list. ListPreference listPreference = (ListPreference) preference; int index = listPreference.findIndexOfValue(stringValue); // Set the summary to reflect the new value. preference.setSummary( index >= 0 ? listPreference.getEntries()[index] : null); } else { // For all other preferences, set the summary to the value's // simple string representation. preference.setSummary(stringValue); } Log.i(TAG, "pref changed : " + preference.getKey() + " " + value); return true; } }; /** * Binds a preference's summary to its value. More specifically, when the * preference's value is changed, its summary (line of text below the * preference title) is updated to reflect the value. The summary is also * immediately updated upon calling this method. The exact display format is * dependent on the type of preference. * * @see #sBindPreferenceSummaryToValueListener */ private static void bindPreferenceSummaryToValue(Preference preference) { // Set the listener to watch for value changes. preference.setOnPreferenceChangeListener(sBindPreferenceSummaryToValueListener); // Trigger the listener immediately with the preference's // current value. sBindPreferenceSummaryToValueListener.onPreferenceChange(preference, PreferenceManager .getDefaultSharedPreferences(preference.getContext()) .getString(preference.getKey(), "")); } } xml/pref_general.xml <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" > <!-- NOTE: EditTextPreference accepts EditText attributes. --> <!-- NOTE: EditTextPreference's summary should be set to its value by the activity code. --> <EditTextPreference android:capitalize="words" android:defaultValue="@string/pref_default_display_name" android:inputType="textCapWords" android:key="example_text" android:maxLines="1" android:selectAllOnFocus="true" android:singleLine="true" android:title="@string/pref_title_display_name" /> <!-- NOTE: Hide buttons to simplify the UI. Users can touch outside the dialog todismiss it.--> <!-- NOTE: ListPreference's summary should be set to its value by the activity code. --> <ListPreference android:defaultValue="-1" android:entries="@array/pref_example_list_titles" android:entryValues="@array/pref_example_list_values" android:key="example_list" android:negativeButtonText="@null" android:positiveButtonText="@null" android:title="@string/pref_title_add_friends_to_messages" /> </PreferenceScreen> values/strings_activity_settings.xml <resources> <!-- Strings related to Settings --> <!-- Example General settings --> <string name="pref_title_display_name">Display name</string> <string name="pref_default_display_name">John Smith</string> <string name="pref_title_add_friends_to_messages">Add friends to messages</string> <string-array name="pref_example_list_titles"> <item>Always</item> <item>When possible</item> <item>Never</item> </string-array> <string-array name="pref_example_list_values"> <item>1</item> <item>0</item> <item>-1</item> </string-array> </resources> NOTE: Actually I just want to comment like "Google's sample for PreferenceActivity is also interesting". But I haven't enough reputation points.So please don't blame me. (Sorry for bad English)

你必须在onCreate方法上使用bindPreferenceSummaryToValue函数。

例子:

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Add 'general' preferences, defined in the XML file
        addPreferencesFromResource(R.xml.pref_general);

        // For all preferences, attach an OnPreferenceChangeListener so the UI summary can be
        // updated when the preference changes.
        bindPreferenceSummaryToValue(findPreference(getString(R.string.pref_location_key)));
        bindPreferenceSummaryToValue(findPreference(getString(R.string.pref_units_key)));
    }

参见Udacity Android课程的第3课:https://www.udacity.com/course/viewer#!/ c-ud853 / l - 1474559101 / e - 1643578599 / m - 1474559101

我的解决方案是创建一个自定义的EditTextPreference，像这样在XML中使用:EditTextPreference android:title="示例title " />

EditTextPreference.java: -

package com.example;

import android.content.Context;
import android.util.AttributeSet;

public class EditTextPreference extends android.preference.EditTextPreference
{
    public EditTextPreference(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);
    }

    public EditTextPreference(Context context, AttributeSet attrs)
    {
        super(context, attrs);
    }

    public EditTextPreference(Context context)
    {
        super(context, null);
    }

    @Override
    protected void onDialogClosed(boolean positiveResult)
    {
        super.onDialogClosed(positiveResult);

        setSummary(getSummary());
    }

    @Override
    public CharSequence getSummary()
    {
        return getText();
    }
}