Copy and Pasted code for Trajectory and got one parsing error...

this is where I copy and pasted the code from and when I paste it into unity I get a parsing error around the world extends in the first line

 public static class TrajectoryActor extends Actor {  
     
     private Controller controller;  
     private ProjectileEquation projectileEquation;  
     private Sprite trajectorySprite;  
     
     public int trajectoryPointCount = 30;  
     public float timeSeparation = 1f;  
     
     public TrajectoryActor(Controller controller, float gravity, Sprite trajectorySprite) {  
         this.controller = controller;  
         this.trajectorySprite = trajectorySprite;  
         this.projectileEquation = new ProjectileEquation();  
         this.projectileEquation.gravity = gravity;  
     }  
     
     @Override  
     public void act(float delta) {  
         super.act(delta);  
         projectileEquation.startVelocity.set(controller.power, 0f);  
         projectileEquation.startVelocity.rotate(controller.angle);  
     }  
     
     @Override  
     public void draw(SpriteBatch batch, float parentAlpha) {  
         float t = 0f;  
         float width = this.width;  
         float height = this.height;  
         
         float timeSeparation = this.timeSeparation;  
         
         for (int i = 0; i < trajectoryPointCount; i++) {  
             float x = this.x + projectileEquation.getX(t);  
             float y = this.y + projectileEquation.getY(t);  
             
             batch.setColor(this.color);  
             batch.draw(trajectorySprite, x, y, width, height);  
             
             t += timeSeparation;  
         }  
     }  
     
     @Override  
     public Actor hit(float x, float y) {  
         return null;  
     }  
     
 }