1 COMP 110 Designing 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 Design Divide 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