如何存储 ArrayList<HashMap<String, String>>在共享首选项中? [英] How can I store an ArrayList&lt;HashMap&lt;String, String&gt;&gt; in SharedPreferences?

问题描述

我希望在 SharedPreferences 中存储一个包含 Hashmap 的 ArrayList.我该怎么做?

解决方案

您可以将您的集合转换为 json 并将其存储在共享首选项中.每当您需要获取数据时，只需获取字符串并将 JSON 转换回您的集合即可.

//将集合转换成JSONJSONArray 结果= new JSONArray(collection);SharedPreferences pref = getApplicationContext().getSharedPreferences(PREF_NAME, 0);//将字符串存储在pref文件中SharedPreferences.Editor prefEditor = pref.edit();prefEditor.putString(KEY, result.toString());prefEditor.commit();//从pref获取JSONString storedCollection = pref.getString(KEY, null);//解析字符串以填充您的集合.ArrayList>collection = new ArrayList>();尝试 {JSONArray 数组 = 新的 JSONArray(storedCollection);HashMap<字符串，字符串>项目 = 空；for(int i =0; i它 = ary.keys();item = new HashMap();而(it.hasNext()){String key = it.next();item.put(key, (String)ary.get(key));}集合.添加(项目)；}} catch (JSONException e) {Log.e(TAG, "同时解析", e);}

JSON 应该如下所示:

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

I wish to store an ArrayList which contains Hashmap inside SharedPreferences. How can I do this?

解决方案

You can convert your collection into a json and store it in shared preference. Whenever you need to get the data, just get the string and convert the JSON back into your collection.

//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);
}

The JSON should look something like this:

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

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