Final Review

2 Final Details Monday, December 11 th 7:00pm – 10:00pm HCC 1325

3 Sections Covered - Detailed View , , [covered 3.4, 3.5 in class] [covered 4.5 in class] , [(basically) covered 5.6 in class] , 6.7, 6.8[covered 6.9 in class] , [covered 7.4 in class] some parts of 12 covered in class notes

4 Sections Covered - Broadly Chapters 1-11  (except for Graphics track)  … with minor exceptions…

5 Other Topics (from before midterm) Running time / Big O notation Working with references handout  including null / this Merge sort Command line arguments printf

6 Other Topics (after midterm) More detailed treatment of some topics  polymorphism (e.g. covered Collections)  file output (e.g. covered buffers and generic Writers)  File input Call Stack Scanning tokens Regular Expressions

7 Chapter 1 Computer processing The Java Programming Language Program Development Object-Oriented Programming  (very basic)

8 Chapter 2 Character Strings Variables and Assignment Primitive Data Types Expressions Data Conversion Interactive Programs

9 Chapter 3 Creating Objects The String Class Packages Formatting Output  (plus more detailed coverage of printf) Enumerated Types Wrapper Classes

10 Chapter 4 Anatomy of a Class Encapsulation Anatomy of a Method

11 Chapter 5 The if Statement and Conditions Other Conditional Statements Comparing Data The while Statement Other Repetition Statements

12 Chapter 6 Software Development Activities Identifying Classes and Objects Static Variables and Methods Class Relationships Interfaces Method Design Testing  (covered the same material in class)

13 Chapter 7 Declaring and Using Arrays Two-Dimensional Arrays The ArrayList Class

14 Chapter 8 Creating subclasses Overriding methods Class hierarchies Inheritance and visibility Designing for inheritance

15 Chapter 9 Polymorphism  polymorphic references  through inheritance  through interfaces Searching  linear search  binary search Sorting  insertion sort  selection sort  merge sort

16 Chapter 10 Exception Handling The try-catch Statement Exception Classes I/O Exceptions

17 Chapter 11 Recursive Thinking Recursive Programming Using Recursion

18 Running Time – Big-O For a parameter n…  e.g. the length of a string or size of an array … count the number of steps performed…  loop through n elements = n steps  loop inside a loop = n 2 steps Ignore constants… coefficients…  3n + 2 steps = O(n)  n 2 /2 steps = O(n 2 )  “cutting problem in half at each step” = O(log n)

19 Working with References null reference  Object variable not assigned anything  When does this cause an exception? this reference  When does this simplify code?

20 File I/O Where do the exceptions happen?  How do we handle them? Why do we want to buffer? How do we buffer? Using Scanner  with default tokens  with defined tokens

21 Regular Expressions Given regular expression  yes/no matching questions  give informal description Given informal description  write regular expression  pass appropriately to Scanner

22 What Kind of Questions? Look at the exercises in the text  finding errors in code  finding differences in code  explaining/defining concepts  predicting output of code  writing methods or classes  specifying/justifying design from requirements

23 What Kind of Questions? Similar format for lecture material  e.g. specify running time  e.g. find null reference problem Using regular expressions Predicting tokens parsed Describe call stack  including exceptions  explain stack trace

24 It May Be on the Test if… It is in the text It is in the lecture notes It is something I said in class or wrote on the blackboard It was part of a lab/assignment

25 What Code Do You Need to Know? Officially: everything as per previous slide Unofficially:  I try to only assume you know “important” methods and classes  … but I decide what is “important”  in general… little used methods that occur rarely in the notes will be given implicitly  but you should know enough code to solve problems without help/look-up

26 Examples There will be definitions (again)  abstract class  checked exception  final method  overridden method

27 Examples There may be explanations required…  Explain why a static method cannot refer to an instance variable.  Give two differences between an abstract class and an interface.

28 Examples Draw a UML diagram for a single class hierarchy representing these animals, with abstract classes grouping animal types  parrot  gorilla  horse  bat  penguin Add an interface for flyers

29 Examples Correct the problems Flyer polly = new Parrot(); Animal koko = new Gorilla(); Gorilla junior = koko.makeOffspring(); polly.layEgg();

30 Examples Define appropriate classes and public methods for the given requirements.  Every salesperson will be assigned a unique ID number, and a numbered office with a phone. Salespeople will sell vacuum cleaners at a fixed price. When inventory runs out, the top salesperson will be designated employee of the month.

31 Examples Find the exception in this code, and handle it. public static void main(String[] args) { FileWriter fileout = new FileWriter(“names.txt”); if(fileout!=null) fileout.write(“John Smith”); else System.out.println(“No name written to file”); }

32 Examples Find the exception in this code, and handle it. public static void main(String[] args) { Student s = new Student( ,”tsmith”); String fname = s.getFirstName(); System.out.println(fname); }

33 Examples Given this information in file.txt: 7 | 5 | 5p,| 4 Write the code that will print these tokens to the screen using a Scanner/delimiter:  “7 | 5 | 5” and “, | 4”  “7 | “ and “ | “ and “p,| 4”

34 Solution Scanner filein = new Scanner( new File(“file.txt”) ).useDelimiter(“p”); while(filein.hasNext()) { System.out.println(filein.next()); } “5”

35 Examples Yes or no expression matching  [1-7]*a? 43  (17)+(17a)?17a  [abc][def](di)?bed  [123]+(45)?a* aaaa  [ab][bc][cde]*abcde  [A-C]DEF?ABCDE  [truck].[stop]+trstopstop yes no yes no

36 Examples Describe the strings matching the expressions  (cat)+  [cat][cat]  cat?  [ca]?t*  (c?a+)t?  [c-t]a?[c-t]*

37 Examples What is the value in variable temp after: int temp = 30; String stemp = temp + “12”; temp = temp + Integer.parseInt(stemp); Again: Collection l = new ArrayList ; int temp = 40; l.add(40); temp = l.size();

38 Examples Write a method that picks a random character in the string “string”.

39 Examples What is wrong with this? How can it be corrected? int count=1,max=0; while(count=max) { System.out.println(count); count-=2; }

40 Examples A LinkedList implements Collection Write a method that adds every word in the sentence “This is a sentence” to a LinkedList, then prints the size.

41 Examples Given double[] input, write a method that returns the highest value

42 Examples Write a class NamedArrayList that extends ArrayList by adding a name for the array list in the first position.

43 Examples What is wrong with these declarations:  char[] chars = {“d”, “a”, “b”};  String[] = new String[5];  Scanner[] sc = new Scanner(5);

44 Examples Write a recursive function that returns true if the input is a power of 3. Write a recursive function that returns true if a string contains only the letter ‘s’.