How to save Arraylist of Objects from Fragment class into SharedPreferencess

Question

I saw similar questions in stackoverflow ( LINK , LINK ) and other websites . They are doing everything from an Activity hence they didn't get problem.

I have an Activity and Fragment class. I am trying to save ArrayList of Object into shared preferences from a Fragment. Below is what i tried

            SharedPreferences prefs = getActivity().getSharedPreferences("SHARED_PREFS_FILE", Context.MODE_PRIVATE);
            SharedPreferences.Editor editor = prefs.edit();
            try {
               editor.putString("taggedFriends",ObjectSerializer.serialize(taggableFriends));

            } catch (IOException e) {
                e.printStackTrace();

Its showing error at ObjectSerializer

**Cannot resolve symbom 'ObjectSerializer'**

I tried

getActivity.ObjectSerializer.serialize(..);

But error didn't go. Help me what can i do now.

Thankyou for spending time for me.

Convert it to json string and save. Than when you need to access read from pref and convert json string to object and use. You can use gson for converting json — savepopulation, Dec 07 '15 at 08:50

Fabio Venturi Pastor · Accepted Answer · 2015-12-11T11:26:04.720

1

Try this:

Last edit:

In this case:

 static class YourObject
{
    private String _name;

    public YourObject(String name)
    {
        this._name = name;  
    } 
}


YourObject yourObject = new YourObject(myName);
ArrayList<YourObject> foo = new ArrayList<YourObject>();
foo.add(yourObject);

convert an ArrayList to JSONArray:

  JSONArray mJSONArray = new JSONArray(foo);

Then save the JSONArray:

 SharedPreferences.Editor editor = prefs.edit();
 editor.putString("yourStringName", mJSONArray.toString());

String to JSONArray:

SharedPreferences prefs = getSharedPreferences("SHARED_PREFS_FILE",   Context.MODE_PRIVATE);
String myJSONArrayString = prefs.getString("yourStringName", "");
JSONArray jsonArray = new JSONArray(myJSONArrayString);

JSONArray to ArrayList:

ArrayList<String> list = new ArrayList<String>();     
   for (int i=0;i<jsonArray.length();i++){ 
    list.add(jsonArray.get(i).toString());
   }

I hope this solve your question.

edited Dec 11 '15 at 11:26

answered Dec 07 '15 at 09:11

Fabio Venturi Pastor

2,519
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You are using ArrayList but i am using ArrayList – Ganesh Dec 07 '15 at 10:38
Thank you, I'll try it and then say you. :) Please wait for a minute – Ganesh Dec 07 '15 at 10:50
It would be useful if you say me how to retrive it in another activity. . – Ganesh Dec 07 '15 at 10:54
: Sorry , it may be my problem in my Class. I don't know how to solve it. I'll write another question and paste link here. Will you please wait for 10 minutes. I really need your help . Thanks.. – Ganesh Dec 07 '15 at 11:03
I think your code is correct, but i am having some other issues in my Class. I hope you can solve it . I'll paste my another questions link here in 5 minutes. Please help me.... – Ganesh Dec 07 '15 at 11:13
Ok no problem ill wait – Fabio Venturi Pastor Dec 07 '15 at 11:18
Sorry to make you wait... here is the link "http://stackoverflow.com/questions/34132418/why-cant-i-use-my-arraylist-variable-outside-facebookcallback" . – Ganesh Dec 07 '15 at 11:25
The Apoorva answer solve your question, put the code inside onSuccess . – Fabio Venturi Pastor Dec 07 '15 at 11:40
I just did, now its having a value. I followed your method but i got a problem . --> JSONArray mJSONArray = new JSONArray(foo); <-- After this, i checked with Log.d(TAG,mJSONArray.toString()); , what i got is null – Ganesh Dec 07 '15 at 11:48
Are you sure if taggableFriends is not null? – Fabio Venturi Pastor Dec 07 '15 at 11:59
Yes i am sure. @Fabio Venturi Pastor – Ganesh Dec 07 '15 at 12:16
You can see on this example how to convert Arraylist in a JsonArray: https://javanotes2all.wordpress.com/2013/03/05/convert-arraylist-to-jsonarray/ Im not sure what is your problem but now im at work, in 2 hrs ill help you. – Fabio Venturi Pastor Dec 07 '15 at 12:26
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/97401/discussion-between-fabio-venturi-pastor-and-ganesh). – Fabio Venturi Pastor Dec 09 '15 at 11:18

score 1 · Answer 2 · answered Dec 07 '15 at 09:55

1

First add Gson to your gradle:

compile 'com.google.code.gson:gson:2.2.4'

Convert your list to Json String like below:

List<String> foo = new ArrayList<String>();
foo.add("Item1");
foo.add("Item2");
foo.add("Item3");

String json = new Gson().toJson(foo );

And save it to shared pref like below:

SharedPreferences.Editor mEditor = mPrefs.edit();
mEditor.putString("yourKey", json);

And when you want to use read your saved json string from pref:

String json = mPrefs.getString("yourKey", "");

Convert your Json String to list of your objects like below. In example i used String.

ArrayList<String> foo = (ArrayList<String>) new Gson().fromJson(json,
                    new TypeToken<ArrayList<String>>() {
                    }.getType());

answered Dec 07 '15 at 09:55

savepopulation

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hey thanks for the answer. will it work for ArrayList – Ganesh Dec 07 '15 at 10:00
It'll work for your custom objects too. If you have problem we can discuss. – savepopulation Dec 07 '15 at 10:03
Also another doubt. I am having object of ArrayList – Ganesh Dec 07 '15 at 10:03
Its saying casting these is redundent while retreving, shall i remove casting in this line 'ArrayList foo = (ArrayList) new Gson().fromJson(json, new TypeToken>() { }.getType());' – Ganesh Dec 07 '15 at 10:20
its just storing "[ ]" value in json string. :-/ its not actually storing any string. – Ganesh Dec 07 '15 at 10:46

How to save Arraylist of Objects from Fragment class into SharedPreferencess

2 Answers2