A constructor is for initialization of an object, for when the object is being created. An actor cannot yet be in any world during its execution. There is no apparent directional changes at that time. Using setRotation in a constructor will only internally set the actor's rotation for when it is finally placed into the world. It is only by way of an act method that some visual change can be made to an actor. Now, the constructor can be used in the setting up of what fields you might need to implement the changes between looking left and right; but the changes themselves would be done at a later time after the constructor was done executing. What do you anticipate is needed to make the actor change from looking one way to another?