如何在SharedPreferences中存儲ArrayList <HashMap <String，String >>？

Question

我希望存儲一個ArrayList，其中包含SharedPreferences中的Hashmap。我怎樣才能做到這一點？

Answer 1

您可以將您的收藏集轉換爲json並將其存儲爲共享首選項。無論何時您需要獲取數據，只需獲取字符串並將JSON轉換回您的集合。

//converting the collection into a JSON 
JSONArray result= new JSONArray(collection); 
SharedPreferences pref = getApplicationContext().getSharedPreferences(PREF_NAME, 0); 

//Storing the string in pref file 
SharedPreferences.Editor prefEditor = pref.edit(); 
prefEditor.putString(KEY, result.toString()); 
prefEditor.commit(); 

//Getting the JSON from pref 
String storedCollection = pref.getString(KEY, null); 
//Parse the string to populate your collection. 
ArrayList<HashMap<String, String>> collection = new ArrayList<HashMap<String, String>>(); 
try { 
    JSONArray array = new JSONArray(storedCollection); 
    HashMap<String, String> item = null; 
    for(int i =0; i<array.length(); i++){ 
     String obj = (String) array.get(i); 
     JSONObject ary = new JSONObject(obj); 
     Iterator<String> it = ary.keys(); 
     item = new HashMap<String, String>(); 
     while(it.hasNext()){ 
      String key = it.next(); 
      item.put(key, (String)ary.get(key)); 
     } 
     collection.add(item); 
    } 
} catch (JSONException e) { 
    Log.e(TAG, "while parsing", e); 
} 

的JSON應該是這個樣子：

[ 
    "{test13=yeah3, test12=yeah2, test11=yeah1}", 
    "{test23=yeah3, test22=yeah2, test21=yeah1}", 
    "{test32=yeah2, test31=yeah1, test33=yeah3}" 
]