Bukkit

public class MyPointsPlugin extends JavaPlugin{
    DataManager<XX> dm;
    public void onEnable(){
        XXLoader myLoader = new XXLoader();
        dm = DataManager<XX>.generateNewDataManager("MyPointsPlugin", this, myLoader);
    }

    public void onDisable(){
        DataManager.removeAndSaveDataManagers(this);
    }

    public boolean onCommand(CommandSender s,Command c,String lbl,String[]args){
        if(c.equalsIgnoreCase("points")){
            s.sendMessage("Points:"+dm.getData(s.getName()).points);
        }else if(c.equalsIgnoreCase("givepoints")){
            if(s.isOp()){
                XX data = DataManager.getData(args[0]);
                data.points=Integer.parseInt(args[1]);
                dm.forceSave(data);
            }
        }
    }
}

class XX extends Data{
    int points;
    XX(DataManager<XX>manager,Player p,JavaPlugin plug){super(manager,p,plug);
        points=0;
    }
    public void onSave(){
        set("points",points);
    }
}
class XXLoader extends DataLoader<XX>{
    @Override
    protected XX loadData(Player p, JavaPlugin plugin) {
        int points=getInt("points",0);
        XX data=new XX(getDataManager(),p,plugin);
        XX.points=points;
        return data;
    }

    @Override
    protected XX getNewData(Player p, JavaPlugin plugin) {
        return new XX(getDataManager(),p,plugin);
    }
}