@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || !(o instanceof AbstractEntity)) return false;
AbstractEntity other = (AbstractEntity) o;
if (this.getObjectId() == null) return false;
else if (this.getObjectId() == other.getObjectId()) return true;
return this.getObjectId().equals(other.getObjectId());
}
/** Add all parts of the car to the world. */
public void addToWorld(World world) {
super.addToWorld(world);
world.addObject(rightFront);
world.addObject(rightRear);
world.addObject(leftFront);
world.addObject(leftRear);
}