存储ArrayList <hashmap <string，string =“”>＆gt;进入SharedPreferences

Question

我想使用jsonarray将arraylist存储到sharedpreferences中。很可能我成功地存储了它，但当我检索JSON数组时，应用程序停止。

代码存储arraylist中的sharedpreferences：

ArrayList<HashMap<String, String>> cart = new ArrayList<HashMap<String, String>>();
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_PID, pid);
map.put(TAG_NAME, name);
map.put(TAG_CATEGORY, category);
map.put(TAG_PRICE, price);
map.put(TAG_IMAGE,String.valueOf(resId));
cart.add(map);

JSONArray result = new JSONArray(cart);

SharedPreferences sharedPreferences = getApplicationContext().getSharedPreferences("CART", 0);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString("item", result.toString());
editor.commit();

Intent a = new Intent("com.example.pb.VIEWCART");
startActivity(a);

检索arraylist的代码：

SharedPreferences sharedPreferences = getApplicationContext().getSharedPreferences("CART", 0);

String storedCollection = sharedPreferences.getString("item", null);
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++) {
        Log.i("CHECKPOINT","into loop" );
        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);
}