Save hashmap in SharedPreferences

Issue

I need to save this hashmap in SharedPreferences i tried to convert it into Json but it didn't work

 Map<String, String> userMap = new HashMap<String , String>() {{
                for(int i = 0; i < userList.size(); i++ ) {
                    String id= userList.get(i).getId();
                    String name = userList.get(i).getName();
                    put(id, name);

                }
            }};
            Gson gson = new Gson();
            String jsonString = gson.toJson(userMap);
            SessionManager sessionManager=new SessionManager(LoginActivity.this);
            sessionManager.saveMap(jsonString); 

jsonString is returing null even usermap has data I really need this to advance in my work appreciate anyhelp.

Solution

Gson is not recognizing the anonymous class that results from doing it that way.

Try initializing the map without using the {{}} construct. e.g.

Map<String, String> userMap = new HashMap<String , String>();

for(int i = 0; i < userList.size(); i++ ) {
    String id= userList.get(i).getId();
    String name = userList.get(i).getName();
    put(id, name);
}

Gson gson = new Gson();
String jsonString = gson.toJson(userMap);
SessionManager sessionManager=new SessionManager(LoginActivity.this);
sessionManager.saveMap(jsonString); 

To convert this json back to a Map<String, String> you can use TypeToken as suggested here.

Gson gson = new Gson();
Type type = new TypeToken<Map<String, String>>() {}.getType();
Map<String, String> nameEmployeeMap = gson.fromJson(jsonString, type);

Answered By - avd