public void receiveXP(int experience) {
   DisplayText.add("", String.format("%s fikk %d studiepoeng!", this.getName(), experience));
   this.experience += experience;
   this.experienceTotal += experience;
   if (this.experienceTotal >= XPNextLevel(level)) {
     levelUp();
   }
 }
  public void levelUp() {
    experience = experience - XPNextLevel(level) + XPNextLevel(level - 1);
    setLevel(level + 1);

    DisplayText.add("", String.format("%s er nå level %d!", this.getName(), level));

    owner.levelUp(this);

    DisplayText.add("", String.format("Du ble litt bedre i %s", this.getName()));

    if (this.experienceTotal >= XPNextLevel(level)) {
      levelUp();
    }
  }