How Android SharedPreferences save/store object

Question

We need to get user objects in many places, which contain many fields. After login, I want to save/store these user objects. How can we implement this kind of scenario?

I can't store it like this:

SharedPreferences.Editor prefsEditor = myPrefs.edit();
prefsEditor.putString("BusinessUnit", strBusinessUnit);

Answer 1

Better is to Make a global Constants class to save key or variables to fetch or save data.

To save data call this method to save data from every where.

public static void saveData(Context con, String variable, String data)
{
    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(con);
    prefs.edit().putString(variable, data).commit();
}

Use it to get data.

public static String getData(Context con, String variable, String defaultValue)
{
    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(con);
    String data = prefs.getString(variable, defaultValue);
    return data;
}

and a method something like this will do the trick

public static User getUserInfo(Context con)
{
    String id =  getData(con, Constants.USER_ID, null);
    String name =  getData(con, Constants.USER_NAME, null);
    if(id != null && name != null)
    {
            User user = new User(); //Hope you will have a user Object.
            user.setId(id);
            user.setName(name);
            //Here set other credentials.
            return user;
    }
    else
    return null;
}

Answer 2

You haven't stated what you do with the prefsEditor object after this, but in order to persist the preference data, you also need to use:

prefsEditor.commit();

Answer 3

My utils class for save list to SharedPreferences

public class SharedPrefApi {
    private SharedPreferences sharedPreferences;
    private Gson gson;

    public SharedPrefApi(Context context, Gson gson) {
        this.sharedPreferences = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
        this.gson = gson;
    } 

    ...

    public <T> void putObject(String key, T value) {
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putString(key, gson.toJson(value));
        editor.apply();
    }

    public <T> T getObject(String key, Class<T> clazz) {
        return gson.fromJson(getString(key, null), clazz);
    }
}

Using

// for save
sharedPrefApi.putList(SharedPrefApi.Key.USER_LIST, userList);

// for retrieve
List<User> userList = sharedPrefApi.getList(SharedPrefApi.Key.USER_LIST, User.class);

.
Full code of my utils // check using example in Activity code

Answer 4

An other way to save and restore an object from android sharedpreferences without using the Json format

private static ExampleObject getObject(Context c,String db_name){
            SharedPreferences sharedPreferences = c.getSharedPreferences(db_name, Context.MODE_PRIVATE);
            ExampleObject o = new ExampleObject();
            Field[] fields = o.getClass().getFields();
            try {
                for (Field field : fields) {
                    Class<?> type = field.getType();
                    try {
                        final String name = field.getName();
                        if (type == Character.TYPE || type.equals(String.class)) {
                            field.set(o,sharedPreferences.getString(name, ""));
                        } else if (type.equals(int.class) || type.equals(Short.class))
                            field.setInt(o,sharedPreferences.getInt(name, 0));
                        else if (type.equals(double.class))
                            field.setDouble(o,sharedPreferences.getFloat(name, 0));
                        else if (type.equals(float.class))
                            field.setFloat(o,sharedPreferences.getFloat(name, 0));
                        else if (type.equals(long.class))
                            field.setLong(o,sharedPreferences.getLong(name, 0));
                        else if (type.equals(Boolean.class))
                            field.setBoolean(o,sharedPreferences.getBoolean(name, false));
                        else if (type.equals(UUID.class))
                            field.set(
                                    o,
                                    UUID.fromString(
                                            sharedPreferences.getString(
                                                    name,
                                                    UUID.nameUUIDFromBytes("".getBytes()).toString()
                                            )
                                    )
                            );

                    } catch (IllegalAccessException e) {
                        Log.e(StaticConfig.app_name, "IllegalAccessException", e);
                    } catch (IllegalArgumentException e) {
                        Log.e(StaticConfig.app_name, "IllegalArgumentException", e);
                    }
                }
            } catch (Exception e) {
                System.out.println("Exception: " + e);
            }
            return o;
        }
        private static void setObject(Context context, Object o, String db_name) {
            Field[] fields = o.getClass().getFields();
            SharedPreferences sp = context.getSharedPreferences(db_name, Context.MODE_PRIVATE);
            SharedPreferences.Editor editor = sp.edit();
            for (Field field : fields) {
                Class<?> type = field.getType();
                try {
                    final String name = field.getName();
                    if (type == Character.TYPE || type.equals(String.class)) {
                        Object value = field.get(o);
                        if (value != null)
                            editor.putString(name, value.toString());
                    } else if (type.equals(int.class) || type.equals(Short.class))
                        editor.putInt(name, field.getInt(o));
                    else if (type.equals(double.class))
                        editor.putFloat(name, (float) field.getDouble(o));
                    else if (type.equals(float.class))
                        editor.putFloat(name, field.getFloat(o));
                    else if (type.equals(long.class))
                        editor.putLong(name, field.getLong(o));
                    else if (type.equals(Boolean.class))
                        editor.putBoolean(name, field.getBoolean(o));
                    else if (type.equals(UUID.class))
                        editor.putString(name, field.get(o).toString());

                } catch (IllegalAccessException e) {
                    Log.e(StaticConfig.app_name, "IllegalAccessException", e);
                } catch (IllegalArgumentException e) {
                    Log.e(StaticConfig.app_name, "IllegalArgumentException", e);
                }
            }

            editor.apply();
        }

Answer 5

To add to @MuhammadAamirALi's answer, you can use Gson to save and retrieve a list of objects

Save List of user-defined objects to SharedPreferences

public static final String KEY_CONNECTIONS = "KEY_CONNECTIONS";
SharedPreferences.Editor editor = getPreferences(MODE_PRIVATE).edit();

User entity = new User();
// ... set entity fields

List<Connection> connections = entity.getConnections();
// convert java object to JSON format,
// and returned as JSON formatted string
String connectionsJSONString = new Gson().toJson(connections);
editor.putString(KEY_CONNECTIONS, connectionsJSONString);
editor.commit();

Get List of user-defined objects from SharedPreferences

String connectionsJSONString = getPreferences(MODE_PRIVATE).getString(KEY_CONNECTIONS, null);
Type type = new TypeToken < List < Connection >> () {}.getType();
List < Connection > connections = new Gson().fromJson(connectionsJSONString, type);

Answer 6

    //SharedPrefHelper is a class contains the get and save sharedPrefernce data

        public class SharedPrefHelper {


        //save data in sharedPrefences


        public static void setSharedOBJECT(Context context, String key, Object value) {

        SharedPreferences sharedPreferences =  context.getSharedPreferences(context.getPackageName(), Context.MODE_PRIVATE);

        SharedPreferences.Editor prefsEditor = sharedPreferences.edit();

        Gson gson = new Gson();

        String json = gson.toJson(value);

        prefsEditor.putString(key, json);

        prefsEditor.apply();   
    }





    //get data from sharedPrefences


     public static Object getSharedOBJECT(Context context, String key) {

     SharedPreferences sharedPreferences 
    =context.getSharedPreferences(context.getPackageName(), Context.MODE_PRIVATE);


    Gson gson = new Gson();

    String json = sharedPreferences.getString(key, "");

    Object obj = gson.fromJson(json, Object.class);

     User objData = new Gson().fromJson(obj.toString(), User.class);

    return objData;

}

}




    //save data in your activity

    User user=new User("Hussein","[e-mail]","3107310890983"); 

    SharedPrefHelper.setSharedOBJECT(this,"your_key",user);

    User data= (User) SharedPrefHelper.getSharedOBJECT(this,"your_key");

    Toast.makeText(this,data.getName()+"\n"+data.getEmail()+"\n"+data.getPhone(),Toast.LENGTH_LONG).show();





    //User is the class you want to save its objects

    public class User {

      public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public String getEmail() {
            return email;
        }

        public void setEmail(String email) {
            this.email = email;
        }

        public String getPhone() {
            return phone;
        }

        public void setPhone(String phone) {
            this.phone = phone;
        }

        private String name,email,phone;
        public User(String name,String email,String phone)
        {
            this.name=name;
            this.email=email;
            this.phone=phone;
        }
    }

//put this in gradle

compile 'com.google.code.gson:gson:2.7'


    hope this helps you :)