Android3.0以上版本中 SharedPreferences新增了函数

abstract Set<String>    getStringSet(String key, Set<String> defValues)
Retrieve a set of String values from the preferences.

同时SharedPreferences.Editor中也新增了函数

abstract SharedPreferences.Editor   putStringSet(String key, Set<String> values)
Set a set of String values in the preferences editor, to be written back once commit() is called.

这样可以直接存储一个字符串集合，但是android3.0以前的版本中没有，如何在android2.3的系统中寻找一种替代他们的方式，我们可以猜想下上面两个函数的实现，直接看代码：

public class SharedPreferencesHandler {final static String regularEx = "|";public static Set<String> getStringSet(SharedPreferences prefs, String key,Set<String> defValues) {String str = prefs.getString(key, "");if (!str.isEmpty()) {String[] values = str.split(regularEx);if (defValues == null) {defValues = new HashSet<String>();for (String value : values) {if (!value.isEmpty()) {defValues.add(value);}}}}return defValues;}public static SharedPreferences.Editor putStringSet(SharedPreferences.Editor ed, String key, Set<String> values) {String str = "";if (values != null | !values.isEmpty()) {Object[] objects = values.toArray();for (Object obj : objects) {str += obj.toString();str += regularEx;}ed.putString(key, str);}return ed;}
}

然后使用的时候可以这样存储和获取一个字符串的集合：

final Set<String> snoozedIds = SharedPreferencesHandler.getStringSet(prefs, PREF_SNOOZE_IDS, new HashSet<String>());// prefs.getStringSet(PREF_SNOOZE_IDS,// new HashSet<String>());snoozedIds.add(Integer.toString(id));final SharedPreferences.Editor ed = prefs.edit();SharedPreferencesHandler.putStringSet(ed, PREF_SNOOZE_IDS,snoozedIds);// ed.putStringSet(PREF_SNOOZE_IDS, snoozedIds);ed.putLong(getAirPrefSnoozeTimeKey(id), time);ed.apply();

上面代码亲测了