Retrieving achievements to display them in a custom view

GetAchievements.java

public abstract class GetAchievements{
    public void loadAchievements(final GoogleApiClient googleApiClient){
        PendingResult<Achievements.LoadAchievementsResult> pendingAchievements = Games.Achievements.load(googleApiClient, true);
        pendingAchievements.setResultCallback(new ResultCallback<Achievements.LoadAchievementsResult>() {
            @Override
            public void onResult(Achievements.LoadAchievementsResult loadAchievementsResult) {
                Game game = Games.GamesMetadata.getCurrentGame(googleApiClient);
                extractAchievements(loadAchievementsResult, game);
            }
        });
    }

    public void extractAchievements(Achievements.LoadAchievementsResult loadAchievementsResult, Game game) {
        AchievementBuffer buffer = loadAchievementsResult.getAchievements();
        List<Achievement> achievementList = new ArrayList<>();
        for (int i = 0; i < game.getAchievementTotalCount(); i++) {
            achievementList.add(buffer.get(i));
        }
        notifyAchievements(achievementList);
    }
    
    public abstract void notifyAchievements(List<Achievement> achievementList);
}