Save hashmap in SharedPreferences

Question

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.

Answer 1

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);