95-712 Object Oriented Programming Java

1. 95-712 Object Oriented Programming Java Lecture 1: Introduction 95-712 Lecture 1: Introduction

2. Structure of the Course • Lectures / class participation • Homework (pencil and paper and programming) • Quizzes • Midterm and Final examinations • Use Blackboard for queries on course material • Send email to me regarding personal issues 95-712 Lecture 1: Introduction

3. Readings • Readings from the required text are assigned for each lecture -- read them in advance. The first reading is due for next week. • Readings from the web also assigned • Look for updates to reading list on schedule 95-712 Lecture 1: Introduction

4. Grading • Programming (5-7) 40% • Three quizzes (low score dropped) 15% • Midterm 20% • Final Exam 25% • I will assign exactly one “A+” per section. 95-712 Lecture 1: Introduction

5. Teaching Assistant: Yubao Office hours will be announced soon. 95-712 Lecture 1: Introduction

6. Important Web Sites • http://www.andrew.cmu.edu/~mm6 • http://www.javasoft.com • http://java.sun.com/docs/books/tutorial/ • http://www.eclipse.org/ • http://www-128.ibm.com/developerworks/rational/library/769.html 95-712 Lecture 1: Introduction

7. Prerequisites to OOP Logic Logical And Logical Or 95-712 Lecture 1: Introduction

8. Prerequisites to OOP Logic Examples of Logical Negation 95-712 Lecture 1: Introduction

9. Prerequisites to OOP Sets Important Sets: • Denotes the empty set • Denotes the set of integers {…,-2, -1,0,1,2,…} R Denotes the set of real numbers {…,-2.9, 4.5, 5.2, …} 95-712 Lecture 1: Introduction

10. Prerequisites to OOPTypes Expressions have types as well as values: ExpressionTypeValue 4+2 integer 6 4<2 boolean false 4>2 boolean true 4.0+2.0 real 6.0 95-712 Lecture 1: Introduction

11. Prerequisites to OOP Algorithm Definition: Informally, an algorithm is a process or set of steps to be followed in calculations or other problem-solving operations, esp. by a computer1. 1. Oxford American Dictionary 95-712 Lecture 1: Introduction

12. Prerequisites to OOPProtocol Definition: Informally, a protocol is a set of rules governing the exchange or transmission of data electronically between devices2. 2. Oxford American Dictionary 95-712 Lecture 1: Introduction

13. Prerequisites to OOPASCII Definition: ASCII is an abbreviation for the American Standard Code for Information Interchange, a set of digital codes representing letters, numerals, and other symbols, widely used as a standard format in the transfer of text between computers3. ASCII is a seven bit code. 3. Oxford American Dictionary 95-712 Lecture 1: Introduction

14. Prerequisites to OOP Unicode Definition: The Unicode Standard is a character coding system designed to support the worldwide interchange, processing, and display of the written texts of the diverse languages and technical disciplines of the modern world. In addition, it supports classical and historical texts of many written languages.4 Unicode characters may vary in size. 4. Unicode.org 95-712 Lecture 1: Introduction

15. Prerequisites to OOPBinary Data The coding schemes mentioned above (ASCII and Unicode) amount to agreements about how characters in various alphabets may be represented as integers. The character “A”, for example, is represented as 6510. But how do we represent the integer 65 in a computer? We usually use the Binary Numbering System. 6510=010000012. So, suppose we encounter the binary value 010000012. What does it mean? Does it mean 6510 or “A” or is it a description of how eight switches are set? We would need to know more about its context to answer that question. 95-712 Lecture 1: Introduction

16. Prerequisites to OOP Text Vs. Binary Why is the binary numbering system used? For much the same reason that we all use base 10 for arithmetic. The algorithms are easy to learn. Try doing long division with Roman numerals. It’s simple to build machines to add and multiply and so on if the numbering system is base 2. In general, character data is encoded into a series of bits using ASCII or Unicode. This is called text data. XML files, for example, are text files. Everything else is binary data. Machine code Files , JPEG files, Java class files, Excel files, etc…, are all binary files. 95-712 Lecture 1: Introduction

17. Prerequisites to OOP Assembly Language • A Programmer is given a problem to solve. • She writes a solution in assembly language. • Two things are on her mind: 1. The problem 2. The machine architecture (number and type of CPU registers, size of memory, memory addresses, instruction set, etc.) • Her solution might look something like this: mul R1,R2,40 add R1,R1,R2 STR Pay,R1 CALL PrintPayCheck • An assembler tool converts this to machine code and the machine code runs on the processor. 95-712 Lecture 1: Introduction

18. Prerequisites to OOP Procedural Language • A Programmer is given a problem to solve. • She writes a solution in Pascal. • Two things are on her mind: 1. The problem and 2. Variables, instructions and procedures that change the state of the variables. Her solution looks something like this: pay := hours * payRate; pay := pay + bonus; printPayCheck(pay); • A compiler converts this to machine code and the machine code is run on the processor. 95-712 Lecture 1: Introduction

19. Prerequisites to OOP Objects • A Programmer is given a problem to solve. • She writes a solution in Java. • Two things are on her mind: 1. The problem. 2. Classes and objects - how they relate and interact Her solution might look something like this: Employee e = new Employee(hours,rate,bonus); e.printCheck(); • This gets compiled into byte code and the byte code is executed by the Java Virtual Machine. 95-712 Lecture 1: Introduction

20. Object Oriented Programming: • is a different way to think about software development. • reduces complexity. • promotes code reuse and flexibility. • promotes important concepts from software engineering, e.g.,abstraction and information hiding. • cannot do anything more than previous paradigms. But can make our lives more enjoyable, software easier to write and reuse. 95-712 Lecture 1: Introduction

21. Prerequisite to OOP:Variables • Variables are addressable areas of memory that change as a program runs. • Variables may contain simple values such as integers or reals. • Variables may contain addresses of other memory locations. These are called pointers or references. • Variable names should be chosen wisely. 95-712 Lecture 1: Introduction

22. Prerequisite to OOP:Modulo Arithmetic • Modulo arithmetic is often a convenient tool to have handy. Informally, it is clock arithmetic. 0 1 + 5 = 0 (mod 6) 12 = 0 (mod 6) 5 + 4 = 3 (mod 6) 2 * 5 = 4 (mod 6) 23 = 5 (mod 6) 1 5 2 4 3 • Without using a clock, divide 23 by 6 and take the remainder. So, 23 mod 6 = 5. 95-712 Lecture 1: Introduction

23. Prerequisite to OOP:Instruction Execution Some problems, or parts of problems, may be solved by a simple series of instructions that when executed in sequence (one after the other) yield the answer or establish a desired state. instruction1; instruction2; instruction3; 95-712 Lecture 1: Introduction

24. Prerequisite to OOP:iteration Some problems require us to iterate or loop over a series of instructions while some condition holds true. while(someConditionHolds) { instruction1; instruction2; instruction3; } 95-712 Lecture 1: Introduction

25. Prerequisite to OOP:Selection Some problems require us to select which group of instructions to execute based upon some criteria. If(someConditionHolds) { instruction1; instruction2; instruction3; } else { instruction4; instruction5; } 95-712 Lecture 1: Introduction

26. Prerequisite to OOP:Application Types • Console applications run within a console window or shell. • GUI (Graphical User Interface) applications control the windowing, buttons and text boxes and are typically event driven. • Client side applications run on a user’s computer that is communicating with another machine. These may be console or GUI applications. • Server side applications typically wait for client generated requests. 95-712 Lecture 1: Introduction

27. Prerequisite to OOPDocumenting Code • Important code is examined by programmers. • Programmers are expensive. • Appropriate use of comments tends to shorten the time required to understand code. • Document clearly and succinctly. • Use the Javadoc tool. • Indent your programs carefully. 95-712 Lecture 1: Introduction

28. Prerequisite to OOPMaking Assertions • Programmers are expensive. • Programs are complex. • The liberal use of assertions helps in debugging. • Make good use of assertions. 95-712 Lecture 1: Introduction

29. Prerequisite to OOPIntegrated Debugging Environments(IDE”s) • Many high quality Java IDE’s exist. • These include Apache Eclipse, Sun’s Netbeans, Oracles JDeveloper, etc. • In this class we will use Eclipse. • You must also know how to compile and run Java from the DOS or Unix command lines. 95-712 Lecture 1: Introduction

30. Compiling and Running a Simple Program import java.io.*; public class TemperatureConverter { public static void main(String args[]) throws IOException { BufferedReader in = new BufferedReader( new InputStreamReader(System.in)); System.out.print("Enter temperature in Fahrenheit>"); 95-712 Lecture 1: Introduction

31. String fahrenheit = in.readLine(); Double fObj = new Double(fahrenheit); double f = fObj.doubleValue(); double c = ((f - 32.0)/9.0) * 5.0; System.out.println("Celsius = " + c); } } 95-712 Lecture 1: Introduction

32. From the command line… javac TemperatureConverter.java java TemperatureConverter 95-712 Lecture 1: Introduction

33. With Eclipse… Create a workspace. Create a Java project. Create a Java class. Switch between the Java and Debug perspectives. 95-712 Lecture 1: Introduction

34. Problems with the code above: • No comments. • No JavaDoc. • Makes no attempt to handle invalid input. • Not object oriented. 95-712 Lecture 1: Introduction