android学习十三 首选项

1，首选项可用用来持久保存用户设置，游戏最高分等

2，首选项有，列表首选项，复选框首选项，对话框首选项..

3，通过xml文件和代码创建首选项

     addPreferencesFromResource(R.xml.main)

4.从首选项中获取值

   Resources resources = this.getResources();

              SharedPreferences spf= PreferenceManager.getDefaultSharedPreferences( this);

              String option = spf.getString(resources.getString(R.string.FLIGHT_SORT_KEY),

                            resources.getString(R.string.FLIGHT_SORT_DEFAULT_VALUE ));

              

              String[] optionArray = resources.getStringArray(R.array.filght_sort_option );

5.判断是否存在某个首选项的值

 

boolean hasPreferences = myPrefs.getBoolean(INITIALIZED, false);
if(hasPreferences) {
Log.v("Preferences", "We've been called before");
// Read other values as desired from preferences file...
someString = myPrefs.getString("someString", "");
}
else {
Log.v("Preferences", "First time ever being called");
// Set up initial values for what will end up
// in the preferences file
someString = "some default value";
}
// Later when ready to write out values

 

6.在代码中设置首选项的值

Editor editor = myPrefs.edit();
CHAPTER 13: Working with Preferences and Saving State  359
editor.putBoolean(INITIALIZED, true);
editor.putString("someString", someString);
// Write other values as desired
editor.commit();

 

 

7.首选项可用嵌套，可以存在父子关系。

 

 

 

 

8一般步骤

 

  a.在xml文件中布局首选项

  b.创建活动继承自PreferenceActivity,然后通过

   addPreferencesFromResource() 创建视图

  c.通过相应的方法获取和设置值