How can I store a HashMap in android using shared preferences?

Question

I have created a HashMap in the following way:

HashMap<Integer, String> buttons = new HashMap<Integer, String>();

I need this to remain in this format, however every answer to this solution I have seen only works for HashMap<String, String>

Thanks

Possible duplicate of [Saving a hash map into Shared Preferences](http://stackoverflow.com/questions/7944601/saving-a-hash-map-into-shared-preferences) — e4c5, Oct 01 '15 at 22:37

score 14 · Accepted Answer · edited Mar 02 '14 at 02:56

14

Hey I found a way in the end :)

I just changed the HashMap I had to format and then did the following to save the contents:

SharedPreferences.Editor editor = getSharedPreferences(PREFS_NAME, 0).edit();
for( Entry entry : backUpCurency_values.entrySet() ) 
editor.putString( entry.getKey(), entry.getValue() );
editor.commit();

and the following to retrieve the HashpMap:

SharedPreferences prefs = getSharedPreferences(PREFS_NAME, 0);
for( Entry entry : prefs.getAll().entrySet() )
   backUpCurency_values.put( entry.getKey(), entry.getValue().toString() );

edited Mar 02 '14 at 02:56

Zied R.

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answered Feb 13 '13 at 15:34

Zyzz

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Very elegant! You could also use `editor.putStringSet(...)` and `prefs.getStringSet(...)`. – Gödel77 Aug 20 '14 at 08:34

score 5 · Answer 2 · answered Feb 13 '13 at 00:48

There is no support for any HashMap in SharedPreferences. You can treat a whole SharedPreferences as being a bit like a HashMap, but it is not a HashMap, and you cannot store a HashMap in an individual preference.

You are welcome to convert your HashMap into a String that could be stored in a SharedPreferences value, such as by converting it into JSON.

score 0 · Answer 3 · answered Feb 13 '13 at 01:50

Converting it to JSON (as CommonsWare pointed out) is an option. Alternatively, the way I did it (since I'm not familiar with JSON) is to serialize it with Apache's ObjectSerializer class (found here: ObjectSerializer.java).

Simply call the serialize method when you want to store it and deserialize when you want to turn it back into a Map.

How can I store a HashMap in android using shared preferences?

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