782: Mainline

Now it is time to consolidate what you have learned. One way to consolidate is to follow what happens when you click on the meter:

• Your click activates a mechanism that calls mouseClicked with the listener connected to the meter instance as the target.
• The mouseClicked method fetches a value based on mouse coordinates from the meter instance.
• Then, the mouseClicked method relays a result to the movie instance using the setters, setScript, setActing, and setDirection, each of which calls setChanged and notifyObservers.
• Each call to the notifyObservers method activates a mechanism that calls the update method in the observer connected to the movie instance.
• The update method fetches information from the movie model and relays that information to the meter view.

The following diagram traces the call sequence:

Movie         LocalMovieObserver    LocalMeterListener      Meter 
instance      instance              instance                instance 
--------      ------------------    ------------------      -------- 
                                                            click event 
                                                              | 
                                      *-----------------------* 
                                      | 
                                      v 
                                    mouseClicked 
                                      | 
                                      *-> getX 
                                      | 
                                      *-> getY 
                                      | 
                                      *-----------------------* 
                                      |                       v 
                                      |           getValueAtCoordinates 
                                      | 
  *-----------------------------------*  
  | 
  v 
setScript 
  | 
  *-> setChanged 
  | 
  *-> notifyObservers  
        | 
        *-------* 
                v  
              update 
                | 
rating <--------* 
                | 
                *---------------------------------------------* 
                                                              | 
                                                              v 
                                                            setValue  
                                                              | 
                                                              v 
                                                            repaint 
                                                              | 
                                                              v 
                                                            paint