Android：无法从 settings.xml 获取偏好值

Question

我的 res 文件夹中有一个 settings.xml 来管理用户设置。我将它加载到一个片段中。为此，我需要将这些设置存储到后端服务中

我已经尝试了许多方法，如下面的代码所示，但我无法读取该值。我尝试使用 Toast 和 log 语句来检查侦听器，但没有出现任何内容，这表明侦听器没有被调用。我是不是做错了什么？

UserSettingFragment.java

public class UserSettingFragment extends PreferenceFragment implements OnSharedPreferenceChangeListener {

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

    addPreferencesFromResource(R.xml.settings);
    //Method 1
    PreferenceScreen shared = getPreferenceScreen();
    shared.setOnPreferenceChangeListener(new OnPreferenceChangeListener() {

        @Override
        public boolean onPreferenceChange(Preference preference, Object newValue) {
            // TODO Auto-generated method stub
            Toast.makeText(getActivity().getApplicationContext(), "Changed", Toast.LENGTH_LONG).show();
            Log.d("preference", "change");
            return true;
        }
    });

    final SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);

    Preference gender = (Preference) findPreference("gender");
    //Method 2
    // Get the custom preference
    Preference mypref = (Preference) findPreference("mypref");
    mypref.setOnPreferenceChangeListener(new OnPreferenceChangeListener() {

        @Override
        public boolean onPreferenceChange(Preference preference, Object newValue) {
            // TODO Auto-generated method stub
            String highScore = sharedPref.getString("gender", "Male");
            Toast.makeText(getActivity().getApplicationContext(), "Changed to " + highScore, Toast.LENGTH_LONG).show();
            Log.d("preference", "change");
            return false;
        }
    });
} //Method 3
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences,
        String key) {
    // TODO Auto-generated method stub
    Toast.makeText(getActivity().getApplicationContext(), "Changed", Toast.LENGTH_LONG).show();
}   

}

settings.xml

<?xml version="1.0" encoding="utf-8"?>

    <SwitchPreference 
        android:key="gender"
        android:title="I am"
        android:switchTextOn="Female"
        android:switchTextOff="Male"
         />

</PreferenceCategory>

Answer 1

由于您使用的是PreferenceFragment，因此您需要在问题中提到的方法#3的onResume 和onPause 方法中注册和取消注册OnSharedPreferenceChangeListener。 p>

public class UserSettingFragment extends PreferenceFragment implements SharedPreferences.OnSharedPreferenceChangeListener {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.settings);
    }

    @Override
    public void onResume() {
        super.onResume();
        getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
    }

    @Override
    public void onPause() {
        super.onPause();
        getPreferenceScreen().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
        Toast.makeText(getActivity().getApplicationContext(), "Changed key: " + key, Toast.LENGTH_LONG).show();
    }
}

Reference