PreviousActivity.userobj

public class UserCreator
{
    public static User getUser(Context context)
    {
        SharedPreferences prefs = context.getSharedPreferences("Name", Context.MODE_PRIVATE);

        //Check if the user is already stored, if is, then simply get the data from
        //your SharedPreference object.

        boolean isValid = prefs.getBoolean("valid", false);

        if(isValid)
        {
            String userName = prefs.getString("username", "");
            String passWord = prefs.getString("password", "");
            ...
            return new User(userName, passWord,...);
        }
        //If not, then store data
        else
        {
            //for example show a dialog here, where the user can log in.
            //when you have the data, then:

            if(...login successful...)
            {
                SharedPreferences.Editor editor = prefs.edit();
                editor.putString("username", "someusername");
                editor.putString("password", "somepassword");
                editor.putBoolean("valid", true);
                ...
                editor.commit();
            }
            // Now, if the login was successful, then you can recall this function,
            // and it will return a valid user object.
            // if it was not, then it will show the login-dialog again.
            return getUser(context);
        }
    }
}

User user = UserCreator.getUser(this);