Data vs. Information 

Think about the problem, what information is available? 

Ą Shark: what do we know about him? 
   where is the shark 
   how hungry is the shark 
Ą Fish: where is the fish? 
   How fast is it swimming? 
   Did it swim out of the game area? 
Ą Game area: 
   How wide, how tall? 
   Background color? 

Data vs. Information 
Ą World consists of the area, the fish and the shark 
Ą Shark 
   Position - consists of the x and y coordinate 
   Life time remaining 
Ą Fish 
   Position - consists of the x and y coordinate 
   ... maybe the speed 
Ą Game area 
   width and height 

We also have to draw the shapes.

Design the classes for Fish, Shark, OceanWorld.

Ą Design Recipe for Data Definition: 
  -- can it be represented by a primitive type? - select the type 
  -- are there several parts that represent one entity? - a class 
  -- are there several related variants? - a union of classes 
  -- add arrows to connect data definitions
 
Ą Convert information to examples of data 
Ą Interpret data as information 
 

Designing the functionality 

Think of the tasks to do:

Ą Move the shark up and down in response to the arrow keys 
Ą Move the fish left as the time goes on 
Ą Replace the fish with a new one if it gets out of bounds 
Ą Check if the shark ate the fish - if yes, replace the fish with a new one 
Ą Starve the shark as the time goes on, check if he is dead 

(Think of the verbs: move, replace, starve, ate, check ...)
(Think of questions: ate the fish? out of bounds? is dead? ...)

Designing the program 

Ą How do you eat an elephant? - one bite at a time 
    One task --- one function/method 

Ą Think systematically about each small task 
Ą Make a wish list if the task is too complex 

Program tasks - somewhat decomposed:

Ą Move the shark up and down in response to the arrow keys 
Ą Move the fish left as the time goes on 
Ą Is the fish out of bounds? 
Ą Replace the fish with a new one 
Ą Can the shark eat the fish 
Ą Shark eats the fish --> fish dies --> is replaced by a new one 
Ą Is the shark dead? 
Ą Starve the shark as the time goes on