COMP 110 Designing and Overloading Methods

1. COMP 110Designing and Overloading Methods Tabitha Peck M.S. March 26, 2008 MWF 3-3:50 pm Philips 367

2. Announcements

3. Questions?

4. Today in COMP 110 • Math Methods • Designing Methods • Overloading Methods

5. Math Methods • abs(double n), returns double • ceil(float n), returns double • floor(double n), returns double • max(int n1, int n2), returns int • min(float n1, float n2), returns float • round(float n), returns int

6. abs(double n) public static double abs(double n) { if ( n < 0 ) return ( n * -1 ); else return n; }

7. ceil(float n) public static double ceil(float n) { return (double) ((int) n + 1); }

8. min(float n1, float n2) public static float min(float n1, float n2) { if ( n1 < n2 ) return n1; else return n2; }

9. Design • How would you design a video game?

10. Top-Down DesignDivide and Conquer • Big Problem • Break problem into smaller subtasks • Break big subtasks into smaller subtasks • Solve subtasks to solve big problem

11. Testing • Subtasks = Methods • If a subtask doesn’t work, your solution isn’t right • Test EVERY method you write

12. Driver programs • Simple program (for only you) • Call methods with different inputs • Positive, negative, zero • True and false • Strings, characters

13. Bottom-Up Testing

14. Driver Program • setMouth(true); • setMouth(false); • setNoseSize(-3); • setNoseSize(2); • setNoseSize(10);

15. Overloading • Using the same method name for two or more methods within the same class • Parameter lists are different • average(double n1, double n2) • average(double n1, double n2, double n3) • Java knows what to use based on the number and types of the arguments

16. Overloading • Change number of arguments • Change argument types • Cannot change only return type

17. Friday • Lab 6