如果您只想显示每个字段的纯文本值作为摘要，那么下面的代码应该是最容易维护的。它只需要两处更改(第13行和第21行，标记为“此处更改”):

package com.my.package;

import android.content.SharedPreferences;
import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
import android.os.Bundle;
import android.preference.EditTextPreference;
import android.preference.ListPreference;
import android.preference.Preference;
import android.preference.PreferenceActivity;

public class PreferencesActivity extends PreferenceActivity implements OnSharedPreferenceChangeListener {

    private final String[] mAutoSummaryFields = { "pref_key1", "pref_key2", "pref_key3" }; // change here
    private final int mEntryCount = mAutoSummaryFields.length;
    private Preference[] mPreferenceEntries;

    @SuppressWarnings("deprecation")
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.preferences_file); // change here
        mPreferenceEntries = new Preference[mEntryCount];
        for (int i = 0; i < mEntryCount; i++) {
            mPreferenceEntries[i] = getPreferenceScreen().findPreference(mAutoSummaryFields[i]);
        }
    }

    @SuppressWarnings("deprecation")
    @Override
    protected void onResume() {
        super.onResume();
        for (int i = 0; i < mEntryCount; i++) {
            updateSummary(mAutoSummaryFields[i]); // initialization
        }
        getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(this); // register change listener
    }

    @SuppressWarnings("deprecation")
    @Override
    protected void onPause() {
        super.onPause();
        getPreferenceScreen().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this); // unregister change listener
    }

    private void updateSummary(String key) {
        for (int i = 0; i < mEntryCount; i++) {
            if (key.equals(mAutoSummaryFields[i])) {
                if (mPreferenceEntries[i] instanceof EditTextPreference) {
                    final EditTextPreference currentPreference = (EditTextPreference) mPreferenceEntries[i];
                    mPreferenceEntries[i].setSummary(currentPreference.getText());
                }
                else if (mPreferenceEntries[i] instanceof ListPreference) {
                    final ListPreference currentPreference = (ListPreference) mPreferenceEntries[i];
                    mPreferenceEntries[i].setSummary(currentPreference.getEntry());
                }
                break;
            }
        }
    }

    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
        updateSummary(key);
    }

}

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"/>

如果适合您的需求，有一些方法可以使其成为更通用的解决方案。

例如，如果你想让所有的列表首选项显示为摘要，你可以为你的onSharedPreferenceChanged实现:

public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
    Preference pref = findPreference(key);

    if (pref instanceof ListPreference) {
        ListPreference listPref = (ListPreference) pref;
        pref.setSummary(listPref.getEntry());
    }
}

这很容易扩展到其他首选项类。

通过使用PreferenceScreen和PreferenceCategory中的getPreferenceCount和getPreference功能，您可以轻松地编写一个泛型函数来遍历首选项树，设置所需类型的所有首选项的摘要到它们的toString表示

如果你使用PreferenceFragment，这就是我解决它的方法。这是不言而喻的。

public static class SettingsFragment extends PreferenceFragment implements OnSharedPreferenceChangeListener {
    @Override
    public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      addPreferencesFromResource(R.xml.settings);
      getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
    }

    @Override
    public void onResume() {
      super.onResume();
      for (int i = 0; i < getPreferenceScreen().getPreferenceCount(); ++i) {
        Preference preference = getPreferenceScreen().getPreference(i);
        if (preference instanceof PreferenceGroup) {
          PreferenceGroup preferenceGroup = (PreferenceGroup) preference;
          for (int j = 0; j < preferenceGroup.getPreferenceCount(); ++j) {
            Preference singlePref = preferenceGroup.getPreference(j);
            updatePreference(singlePref, singlePref.getKey());
          }
        } else {
          updatePreference(preference, preference.getKey());
        }
      }
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
      updatePreference(findPreference(key), key);
    }

    private void updatePreference(Preference preference, String key) {
      if (preference == null) return;
      if (preference instanceof ListPreference) {
        ListPreference listPreference = (ListPreference) preference;
        listPreference.setSummary(listPreference.getEntry());
        return;
      }
      SharedPreferences sharedPrefs = getPreferenceManager().getSharedPreferences();
      preference.setSummary(sharedPrefs.getString(key, "Default"));
    }
  }

简单:

listPreference.setSummary("%s");