How to Store Hashmap to android so that it will be reuse when application restart using shared preferences?

Question

I want to store hashmap to my android application that when restart ,it shows last saved values of hashmap.

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

is my hashmap and 44 values are stored in it dynamically. That works fine!!! now,I want to store it for future use(Application restart or reuse).

Answer 1

You could serialize it to json and store the resulting string in the preferences. Then when application restarts get the string from preferences and deserialize it.

EDIT :

To do so you can use Google Gson for example.

You will need to wrap your map in a class:

public class MapWrapper {
  private HashMap<Integer, String> myMap;
  // getter and setter for 'myMap'
}

To store the map:

Gson gson = new Gson();
MapWrapper wrapper = new MapWrapper();
wrapper.setMyMap(HtKpi);
String serializedMap = gson.toJson(wrapper);
// add 'serializedMap' to preferences

To retrieve the map:

String wrapperStr = preferences.getString(yourKey);
MapWrapper wrapper = gson.fromJson(wrapperStr, MapWrapper.class);
HashMap<Integer, String> HtKpi = wrapper.getMyMap();