1. Welcome to IIT and cs115!

2. CS 115 - Secs. 001 Jon Hanrath - SB112B hanrath@iit.edu

3. Lecture/Lab: TR
1:00 P.M. –4:00 P.M. SB 112E
Lectures will be followed by lab time. Lab assignments are due by the end of class on Thursdays each week.

4. CS 115 – Required Textbook
“Java 6 Illuminated: An Active Learning Approach” Second or Third or Fourth Edition, Anderson and Franceschi

5. CS 115 - Quizzes/Exams & Grading
1 Quiz –5% of Grade
2 Exams:
Exam I - Lecture Exam - 15%
Exam II - Lecture Exam - 25%
Final Exam - 35%
Labs - 20%
Must Take Final to Pass Course
Final Grade:
A > 90%
B %
C 70 –79.99%
D 60 – 69.99%
E < 60%

6. CS115 Labs
Labs Consist of a Reading Assignment, and Lab Exercises from Website
Lab Exercises Comprised of Written Exercises and Programming Exercises
Lab Exercises Due by End of Class Thursdays
Students Receive Full Credit for Attempting Each Problem
Lab Exercises Not Corrected or Handed Back
Labs Graded Either 10 (fully completed), 5 (partially completed), or 0 (not completed)

7. Expectations Attendance in Lectures and Labs
Completion of Quizzes and Exams
Four to Six Hours per Week on Homework
Outside Help If Necessary
No Cheating
Have fun!!

8. Rules No Swearing or Other Inconsiderate Behavior
Turn Off Cell Phones, iPads, Laptops
Questions, Discussion, Ideas Welcome

9. Excuses
If You Will Miss an Exam or Quiz, Make Arrangements **BEFORE** the Exam or Quiz Date
Exam, Quiz Dates Already Posted
If Emergency:
Doctor/Hospital Note
Family Problem: Contact Info for Parents

10. Unacceptable Excuses Slept Late Felt Sick I’m Just a Freshman
Roommate Ate My Alarm Clock/Textbook/Underwear
Missed Bus
Had a Game/Match/Practice
Didn’t Know When Exam/Quiz Was
If Any of Above Happen, Get to Class As SOON as Possible!!!

11. CS 115 - Ethics Exams: Labs Should Be Done Independently
Closed Book, Closed Notes, Closed Everything
Nothing in Ears (mp3 players, cell phones, etc.)
Labs Should Be Done Independently

12. CS 115 – Where to Get Help www.cs.iit.edu/~cs115hanrath
Internet: Search for “JAVA tutorial”, or “JAVA help”
GET HELP EARLY RATHER THAN LATER!!!

13. CS 115 – Web Page http://www.cs.iit.edu/~cs115hanrath
Click on Syllabus
Weekly Assignments
Quiz and Exam Dates
Lecture Slides
Other Course Information

14. CS115 Labs (Cont) All Labs Assigned from Website
Work on Labs on Personal PC, or Campus Computers
Save .java File(s) to flash drive, or send to yourself in and Bring to Lab Section for Discussion and Questions
Hand in assignments by end of class Thursday

15. Course Philosophy Computer Science Side “Real World” Side
Problem Solving
Logical Thought
Programming in JAVA
“Real World” Side
Human Nature
Corporate World
Surviving during and after College

16. Problem Solving
CS 115 Develops Logic Skills to Solve Problems by Writing a Program
A Program is a Problem Solving Tool
Computers Follow Instructions Given to Them
Computers Do Not Have “Intuition”
Computers Do Not Make Decisions “on Their Own”

17. Why Use a Program?
Computers Perform Tasks Many Times Faster than a Person
Computers Are More Consistent than a Person
Computers Can Work 24-7

18. Terminology
Source Code: the Original Problem-Solving, Logical Solution Written in a Programming Language (e.g. JAVA, .java file)
Interpretation: Converting source code into common language (.class file)
Compiling: the Action of Turning the Source Code into a Format the Computer Can Use
Linking: the Action of Bringing in Already Written Code (Libraries) for Use in a New Program
Executable: the Result of Compiling and Linking a Source Program; the “.exe” file that the Computer Can Run

19. JAVA Required Elements
Every JAVA Program Must Have:
public class MyProgram {
public static void main( String [ ] args) }

20. Your First Program { System.out.println(“Hello World!!”); }
// Jon Hanrath
// CS115
// Section 042
public class MyProgram {
public static void main( String [ ] args)
System.out.println(“Hello World!!”);
System.exit(0); }

21. Writing a JAVA Program Design Design Team (Experienced) Pseudocode
In Practice, 75% of Total Program Time
Program
Java, C++, etc.
Coders (Less Experienced)
Test
Test Team
If Even One Error, Back to Design

22. What Is Pseudocode?
Every Programmer’s Way of Writing Down Steps in Solving a Problem
Steps in Creating Pseudocode:
Understand the Problem
Decide How to Solve the Problem
Write the Solution Using a Logical Sequence of Statements
Design Issues Apply to almost ANY Vocation

23. Compiler Converts Source Code into an Object File or Machine Code
Each Change to Source File Requires a Recompilation
Compiler Detects Syntax Errors
Syntax Error: a Non-Proper, Not Allowable, Sequence of Characters or Words Given a Particular Language

24. Syntax Errors Spelling Errors Examples: Punctuation Errors Examples:
Undefined Variable Name
Unrecognized Keyword
Punctuation Errors Examples:
Missing Curly Braces
Missing Semicolons
Malformed Comments
Syntax Errors Are Listed at Bottom of Screen When Compilation Is Complete

25. Syntax Errors (Cont)
Syntax Errors Are Listed at Bottom of Screen When Compilation Is Completed
First Error in Program May “Cause” Other Errors to Show Up
General Rule: Fix First Error (and Any Obvious Errors); Then Recompile

26. Logic Errors – “Bugs” Also Called Semantic or Run-Time Errors
Program Compiles, but Doesn’t Produce the Expected Results
Examples:
Program Keeps Running Forever (Infinite Loop)
Nothing Happens
Program Output Is Incorrect
Error Message at Run Time (e.g. Dividing by 0)
Errors May Be Intermittent
May Be Able to Find Semantic Problems with Debugger

27. Debugging public class MyProgram {
public static void main( String [ ] args)
System.out.println(“Program Begins” );
// first 10 lines of program
System.out.println(“ Made it to line 10”);
// next 10 lines of program
System.out.println(“ Made it to line 20” );
//… and so on
System.out.println(“ Made it to line 100” ); }

28. Detecting “Bugs”
Running Program Should Be Tested Several Times with Different Inputs
Test Plan – Series of tests (e.g., inputs) that have predetermined expected outputs.
Running Program Should Be Tested Several Times under All Potential Conditions
When Errors Detected: Analysis Needed: Debugging Mechanism

29. Test Plan
What should the Test Plan contain for a program that accepts numerical input from a user, and outputs the square of the input?

30. JAVA Packages/Libraries
Over 2000 Libraries Exist
Sometimes Called “Packages”
Java.lang Package Automatically Imported
Import Statements Above First Class
Import Others with import statement
import java.util.* //import all classes

31. Comments Comments: Describe a Program // Comment to end of line
/* Comment until first occurrence of star slash */
Difficult to Understate Importance of Good Comments
Should Be at Beginning of Program (Overall Summary)
Should Be Next to Variable Declaration Briefly Describing Uses of Variable
Should Be Anywhere in Program Where Unobvious Coding Is Performed

32. Program Format Not Recognized by Compiler
White Space:
Not Recognized by Compiler
Indent (e.g. 3 Spaces) for Each New Function, Selection, or Loop
public class MyProgram{public static void main( String [ ] args){System.out.println(“Hello World!!”);System.exit(0);}}
.vs
public class MyProgram {
public static void main( String [ ] args)
System.out.println(“Hello World!!”);
System.exit(0); }

33. Variables Identifiers Used to Store Values that May Change
Every Variable Has a Type : What Kind of Value (e.g., Integer, Floating Point Number, Character) Is Begin Stored
Every Variable Has a Value which Is Assigned and Can Be Changed
Every Variable Must Be Declared, which Sets Aside Memory for the Storage Location

34. Declaring a Variable
Declaration Normally Comes after a Function Definition Opening Curly Brace:
public class MyProgram {
public static void main( String [ ] args)
int num1; //variable declaration
num1 = 10; // variable assignment
// variable output below
System.out.println(“num1 is:” + num1); }
Declaration Includes Type and the Name of the Variable
All Variables Must Be Declared before Being Used

35. Variables and Main Memory
int num;
num = 10;
num = 15;
num
<garbage>
num 10
num 15

36. Main Memory Storage Location of Data in a Computer
Used When a Program Is Running
“Wiped Clean” When Computer Rebooted
Bit: Represents One Wire of Computer (On or Off, i.e., “1” or “0”)
Byte: Basic Unit of Storage (Can Store One Letter of the Alphabet) (8 bits per byte…256 combinations)
Kilobyte (KB): 1000 (or 1024) Bytes (Pages of Text)
Megabyte (MB): 1,000,000 Bytes (Large Pictures)
Gigabyte (GB): 1,000,000,000 Bytes (Music Files, Video Files)

37. Initialization and Assignment
Initialization: Value Given to Variable at Declaration
Assignment: Value Given to Variable in Execution Statement

38. Variable Initialization
public class MyProgram {
public static void main( String [ ] args)
int num1 = 10; //variable initialization
System.out.println(“num1 is:” + num1); }

39. Built-In (or Primitive) Data Types for Variables
int: Integer Range of Typically –2,147,483,648 to 2,147,483,647 (machine and compiler dependent)
float: Real Number (i.e., integer part, decimal part, and exponent part) Range of Typically (+/-) 10e-45 to 10e38
double: Larger Real Number ((+/-) 10e-324 to 10e308)
char: Character

40. Naming Variables in JAVA: Identifiers
Can Use Letters: Remember That JAVA is Case Sensitive (e.g., NumWidgets Is Not the Same as numwidgets)
Can Use Digits 0-9, $, and Underscore
Cannot Start with a Digit
Cannot Contain Spaces or Other Characters
Cannot Use JAVA Keywords

41. Naming Variables (Cont)
Should Use a Meaningful, Descriptive Name so that Variable’s Use Is Easily Understood:
Examples:
counter, second, minute, length, width
Be Consistent with Case; Usually Lower Case with Upper Case for Second Part of Variable Name
averageRainfall, totalStudentGrades, maxBuildingHeight, minPackageWeight;

42. Variable Scope
Scope: Area of a Program within which a Variable Can Be Referenced
Variable Definitions Are Recognized in the Curly Braces in which They Were Defined
Variables Declared Outside of Functions Are Recognized from the Point Declaration through the Rest of the Program

43. Named Constants
Constant: An Identifier that Is Initialized to a Value that Cannot Change
Usually Declared at Top of Program using Keyword final
Standard Naming of Constants Is to Use All Upper Case Letter with or without Underscore between Words
All Constants Should Be Initialized
Syntax: final int MAXHT = 100;

44. Advantages of Constants
Easier to Understand
Easier to Modify
Example: Compare using Number 5000 in Program versus Constant MAXHT

45. Named Constants public class MyProgram {
public static void main( String [ ] args)
final int MAXHT = 100;
...
currentHeight > MAXHT
bridgeHeight == MAXHT
bridgeHeight + newAddition >= MAXHT
... // used MAXHT 223 times in this program }

46. Literal Constants (Values)
Constants Whose values Are Already Known:
Characters (Specified Inside Single Quotes):
‘A’ , ‘a’ , ’5’ , ’ ‘ , ’\n’ (newline) , ’\0’ (NULL Character)
Integers:
10, , -34
Float or Double:
2.3, , 10.6e6
String (Specified Inside Double Quotes):
“HELLO” , “What a great deal.” , “5”

47. Input and Output Also Known as I/O Output : Input (Scanner):
System.out.println(“Hello World!!”);
Input (Scanner):
import java.util.Scanner;
Scanner scan = new Scanner(System.in);
scan.nextInt();
scan.nextFloat();
scan.nextDouble();
scan.next(); //String to whitespace
scan.nextLine(); // String to end of line
All JAVA Statements End in Semicolon (;)

48. Input and Output Example
import java.util.Scanner;
public class MyProgram {
public static void main( String [ ] args)
Scanner scan = new Scanner(System.in);
int numEntered;
System.out.print(“Enter an integer:”);
numEntered = scan.nextInt();
System.out.println(“You entered: “ + numEntered); }

49. Characters and Strings
Strings in java.lang package
Java.lang imported automatically

50. JAVA Strings Declaration: String yourName;
Assigning a Value to a String:
yourName = “A. Goose”;
String Constants (Values) Must Be Enclosed in Double Quotes

51. Input String Example import java.util.Scanner; public class MyProgram{
public static void main( String [ ] args)
Scanner scan = new Scanner(System.in);
String lastname;
System.out.print(“Enter last name:”);
lastname = scan.next();
System.out.println(“You entered: “ + lastname); }

52. Expressions
Expression: A Sequence of One or More Identifiers and Operators that Evaluates to a Value
Operator: A Symbol Expressing a Way to Modify a Value or Values (e.g., + for Addition)
Operand: A Value Being Modified by an Operator
Example Expressions: 5
currentHeight
currentHeight + 10

53. Arithmetic Expressions
Standard Arithmetic Operations Can Be Performed: Addition, Subtraction, Multiplication, Division
Standard Arithmetic Operators Can Be Used for These Operations: +, -, *, /
Others:
% - “Modulo (Mod)” – Remainder after Integer Division
Example: int num1 = 9, num2 = 5;
num1 / num2 is 1 (NOT 1 point something)
num1 % num2 is 4
-- Decrement (Subtract 1)
++ Increment (Add 1)
num1++; is the same as num1 = num1 + 1;

54. Order of Operations Precedence: Level of Importance of Operations
Multiplicative Operators Have Higher Precedence than Additive Operators:
*, /, % Higher
+, - Lower
Associativity: Order of Operation for Equal Level Precedence
Most Operators Have Left-to-Right Associativity
Use Parentheses to Force Differing Precedence of Operations

55. Precedence/Associativity
int num1 = 9, num2 = 6, num3 = 8, num4 = 4;
num4 = num1 + num2 * num3;
num4 = num1 / num2 * num3;