1. Midterm Exam 2 75 points 1 min per point Allocate time proportionate to points Closed book Chapters 6-9 Look at exercises

2. Exam Question Difficulty Obvious questions Questions requiring studying Challenging questions Hardness of exam proportional to hardness of assignments

3. Question Nature Essay Questions Understanding Code Writing/Modifying Code Example syntax

4. Essay Questions Definitions –Define class method. Distinction –Distinguish class and instance methods. Rationale –Why class methods? Comparison –Pros and Cons of using Class and Instance Methods

5. Understanding Code Identify Errors –Class Vs Interfaces as Types –Static Vs instance methods/constants/variables –Off-by-one errors –Infinite loops –Null pointers –….

6. Understanding Code Identify Style Principle Violations –Class as Types –Instance methods/constants instead of class methods/constants –Code duplication in If-Else –No separation of Concerns –Side Effects –...

7. Understanding Code Identify Errors & Style Violations public interface Money { public int getPounds(); public int getDollars(); public int DOLLARS_IN_LB = 1.8; } public class PoundMoney implements Money { static int assets; public static int getPounds() { return assets; } public int getDollars() { return assets*DOLLARS_IN_LB; } }

8. Understanding Code Characterize Code –Overloaded & Polymorphic Methods –Static & Instance Variables –Logical & Physical Structure –Counter & Event-controlled loops –Side Effects –...

9. Understanding Code Trace execution (explain output) of programs involving –Conditionals –Loops –Class/instance variables –Constructors –main method

10. Understanding Code (example) What is the output of the following loops, when n is (i) 4 and (ii) –4. a) while (n >= 0) { n = n –1; System.out.println (n); } b) while (n != 0) { n = n –1; System.out.println (n); }

11. Writing Code Improve Code by removing style principle violations. E.g: public void fancyPrintGrade(int score) { if (score < PASS_CUTOFF == true) { System.out.println("FAILED"); System.out.println("**************"); System.out.println("Need to take the course again."); } else { System.out.println("PASSED"); System.out.println("**************"); System.out.println("Congratulations!"); }

12. Writing Code Write Functions/Procedures/Main Methods/Classes Involving –Loops, Conditionals, Static Vars,... –E.g: Write a program that prints all positive odd numbers less than some limit n.