SharedPreferences不适用于所有活动

Question

我试图在一个活动中保存一些过滤器/状态，然后在下一个活动中使用该数据。

我使用SharedPreferences，但它不像我预期的那样工作。

public class FilterActivity extends Activity { 

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

    EditText distanceEditor; 

    @Override 
    public void onPause() { 
    super.onPause(); 
    SharedPreferences preferences = getSharedPreferences(PreferenceKey.FILTER_PREFERENCES_NAME, MODE_WORLD_READABLE); 
    String distance = distanceEditor.getText().toString(); 
    preferences.edit().putString(PreferenceKey.DISTANCE, distance); 
    preferences.edit().commit(); 
    Log.i(TAG, "Wrote max-distance=" + distance); 

    Log.i(TAG, "Preferences contains distance=" + preferences.getString(PreferenceKey.DISTANCE, "FAIL")); 
    } 


    public static class PreferenceKey { 
    public static final String FILTER_PREFERENCES_NAME = "FilterActivity:" + "Filter_Preference_File"; 
    public static final String DISTANCE = "FilterActivity:" + "DISTANCE"; 
    } 
} 

然后，应该使用这种偏好的活动：

public class MapActivity extends MapActivity { 
    @Override 
    public void onResume() { 
    super.onResume(); 

    SharedPreferences preferences = getSharedPreferences(FilterActivity.PreferenceKey.FILTER_PREFERENCES_NAME, MODE_WORLD_READABLE); 
    String maxDistance = preferences.getString(FilterActivity.PreferenceKey.DISTANCE, "FAIL"); 

    Log.i(TAG, "Read max-distance=" + maxDistance); 
    } 
} 

但输出我得到的是：

.FilterActivity(4847): Wrote max-distance=99.9 
.FilterActivity(4847): Preferences contains distance=FAIL 
.MapActivity(4847): Read max-distance=FAIL 

谁能告诉我，我做错了什么吗？

我正在针对API Level-8进行开发。

Answer 1

在下面的两行，被返回

preferences.edit().putString(PreferenceKey.DISTANCE, distance); 
preferences.edit().commit(); 

两个不同SharedPreferences.Editor秒。因此，价值没有被承诺。相反，你必须使用：

SharedPreferences.Editor spe = preferences.edit(); 
spe.putString(PreferenceKey.DISTANCE, distance); 
spe.commit();