How to save an ArrayList

Question

I I have ab ArrayList which is containing ArrayLists, they are again containing lists. One of Strings and one of Views. How could i save This root list to Shared Preferences or in any other was? Here is an overview:

           MotherList
                | 
                .
          DaughterLists
            /       \
           /         \
    ListOfViews  ListOfStrings
                .
                .

Why do you want to save an `android.view.View` in a `SharedPreferences`? I don't understand what it means. — Paul Boddington, Apr 07 '16 at 23:58
Why are you even holding on to a list of views? This sounds like a recyclerview scenario... — Shmuel, Apr 08 '16 at 00:42
Perhaps a duplicate of [this](http://stackoverflow.com/q/7057845/642706) and [this](http://stackoverflow.com/q/21794419/642706)? — Basil Bourque, Apr 08 '16 at 01:12
@RedDragon, you can use to "LinkedHashMap" for implementing your idea — Bhunnu Baba, Apr 08 '16 at 05:13

xinxin yao · Answer 1 · 2016-04-08T05:23:23.187

Here are all of methods about put data in SharedPreferences: putBoolean(String key,boolean v) putInt(String k,int v) putFloat(String k,float v) putLong(String k,long v) putString(String k,String v) putStringSet(String k,Set v)

But there is a open-source frame called ASimpleCache can solve it:

save: ACache acache = ACache.get(Context); acache.put("key",your-root-list); get: acache.getAsObject("key");

score 0 · Answer 2 · answered Apr 08 '16 at 04:51

0

Store Arraylist Using Shared Preferences

SharedPreferences prefs=this.getSharedPreferences("yourPrefsKey",Context.MODE_PRIVATE);
Editor edit=prefs.edit();

Set<String> set = new HashSet<String>();
set.addAll(your Arraylist Name);
edit.putStringSet("yourKey", set);
edit.commit();

Retrieve Arraylist from Shared Preferences

Set<String> set = prefs.getStringSet("yourKey", null);
List<String> sample=new ArrayList<String>(set);

answered Apr 08 '16 at 04:51

Tushar Narang

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You can convert it to JSON String and store the string in the shared preferences. – Tushar Narang Apr 08 '16 at 04:52

score 0 · Answer 3 · answered Apr 08 '16 at 05:15

Hello I suggest you to use GSON , for serializing and deserializing your list. By this way you can save it on your SharedPreferences easily.

First convert your ArrayList<List> object to JSON with help of GSON Converter

String myArrayListAsJSON = new Gson().toJson(myArrayList); // you will pass your arraylist variable to toJson() method

Save your JSON Object as String on your SharedPreference

SharedPreferences prefs=this.getSharedPreferences("PREF_KEY_FOR_YOUR_APP",Context.MODE_PRIVATE);
Editor edit=prefs.edit();

edit.putString("myListKey", myArrayListAsJSON); // we will put our list hat serialized with GSON here
edit.commit();

Re-use your list at any place/time of your application. You will just need to deserialize your JSON that you saved on your Shared Preferences

SharedPreferences prefs=this.getSharedPreferences("PREF_KEY_FOR_YOUR_APP",Context.MODE_PRIVATE);
String myListAsString = prefs.getString("myListKey","default_value");
ArrayList<List> yourObject = new Gson().fromJson(myListAsString, YOUR_MODEL.class);

Gson is a Java library that can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object. Gson can work with arbitrary Java objects including pre-existing objects that you do not have source-code of.

You can use GSON in your app by adding this line to your dependencies.

compile 'com.google.code.gson:gson:2.6.2'

You can find more detail and example on GSON Github Page

How to save an ArrayList

3 Answers3